More from Electronics etc…
Introduction Finding the Display Tuning Potentiometers The Result Hardcopy Preview Mode Introduction Less than a week after finishing my TDS 684B analog memory blog post, a TDS 684C landed on my lab bench with a very dim CRT. If you follow the lives the 3-digit TDS oscilloscope series, you probably know that this is normally a bit of death sentence of the CRT: after years of use, the cathode ray loses its strength and there’s nothing you can do about it other than replace the CRT with an LCD screen. I was totally ready to go that route, and if I ever need to do it, here are 3 possible LCD upgrade options that I list for later reference: The most common one is to buy a $350 Newscope-T1 LCD display kit by SimmConn Labs. A cheaper hobbyist alternative is to hack something together with a VGA to LVDS interface board and some generic LCD panel, as described in this build report. He uses a VGA LCD Controller Board KYV-N2 V2 with a 7” A070SN02 LCD panel. As I write this, the cost is $75, but I assume this used to be a lot cheaper before tariffs were in place. If you really want to go hard-core, you could make your own interface board with an FPGA that snoops the RAMDAC digital signals and converts them to LVDS, just like the Newscope-T1. There is a whole thread about this the EEVblog forum. But this blog post is not about installing an LCD panel! Before going that route, you should try to increase the brightness of the CRT by turning a potentiometer on the display board. It sounds like an obvious thing to try, but didn’t a lot of reference to online. And in my case, it just worked. Finding the Display Tuning Potentiometers In the Display Assembly Adjustment section of chapter 5 of the TDS 500D, TDS 600C, TDS 700D and TDS 714L Service Manual, page 5-23, you’ll find the instructions on how to change rotation, brightness and contrast. It says to remove the cabinet and then turn some potentiometer, but I just couldn’t find them! They’re supposed to be next to the fan. Somewhere around there: Well, I couldn’t see any. It’s only the next day, when I was ready to take the whole thing apart that I noticed these dust covered holes: A few minutes and a vaccum cleaning operation later reveals 5 glorious potentiometers: From left to right: horizontal position rotation vertical position brightness contrast Rotate the last 2 at will and if you’re lucky, your dim CRT will look brand new again. It did for me! The Result The weird colors in the picture above is a photography artifact that’s caused by Tektronix NuColor display technology: it uses a monochrome CRT with an R/G/B shutter in front of it. You can read more about it in this Hackaday article. In real life, the image looks perfectly fine! Hardcopy Preview Mode If dialing up the brightness doesn’t work and you don’t want to spend money on an LCD upgrade, there is the option of switching the display to Hardcopy mode, like this: [Display] -> [Settings <Color>] -> [Palette] -> [Hardcopy preview] Instead of a black, you will now get a white background. It made the scope usable before I made the brightness adjustment.
Introduction The TDS600 Series The Acquisition Board Measuring Along the Signal Path A Closer Look at the Noise Issue Conclusion Introduction I have a Tektronix TDS 684B oscilloscope that I bought cheaply at an auction. It has 4 channels, 1 GHz of BW and a sample rate of 5 Gsps. Those are respectable numbers even by today’s standards. It’s also the main reason why I have it: compared to modern oscilloscopes, the other features aren’t nearly as impressive. It can only record 15k samples per channel at a time, for example. But at least the sample rate doesn’t go down when you increase the number of recording channels: it’s 5 Gsps even all 4 channels are enabled. I’ve always wondered how Tektronix managed to reach such high specifications back in the nineties, so in this blog post I take a quick look at the internals, figure out how it works, and do some measurements along the signal path. The TDS600 Series The first oscilloscopes of the TDS600 series were introduced around 1993. The last one, the TDS694C was released in 2002. The TDS684 version was from sometime 1995. The ICs on my TDS684C have date codes from as early as the first half of 1997. The main characteristic of these scopes was their extreme sample rate for that era, going from 2 Gsps for the TDS620, TDS640 and TDS644, 5 Gsps for the TDS654, TDS680 and TDS684, and 10 Gsps for the TDS694C which was developed under the Screamer code name. The oscilloscopes have 2 main boards: the acquisition board contains all the parts from the analog input down to the sample memory as well as some triggering logic. (Click to enlarge) a very busy CPU board does the rest. (Click to enlarge) 2 flat cables and a PCB connect the 2 boards. The interconnect PCB traces go to the memory on the acquisition board. It’s safe to assume that this interface is used for high-speed waveform data transfer while the flat cables are for lower speed configuration and status traffic. If you ever remove the interconnection PCB, make sure to put it back with the same orientation. It will fit just fine when rotated 180 degrees but the scope won’t work anymore! The Acquisition Board The TDS 684B has 4 identical channels that can easily be identified. (Click to enlarge) There are 6 major components in the path from input to memory: Analog front-end Hidden under a shielding cover, but you’d expect to find a bunch of relays there to switch between different configurations: AC/DC, 1Meg/50 Ohm termination, … I didn’t open it because it requires disassembling pretty much the whole scope. Signal Conditioner IC(?) This is the device with the glued-on heatsink. I left it in place because there’s no metal attachment latch. Reattaching it would be a pain. Since the acquisition board has a bunch of custom ICs already, chances are this one is custom as well, so knowing the exact part number wouldn’t add a lot of extra info. We can see one differential pair going from the analog front-end into this IC and a second one going from this IC to the next one, an ADG286D. National Semi ADG286D Mystery Chip Another custom chip with unknown functionality. Motorola MC10319DW 8-bit 25 MHz A/D Converter Finally, an off-the-shelf device! But why is it only rated for 25MHz? National Semi ADG303 - A Custom Memory Controller Chip It receives the four 8-bit lanes from the four ADCs on one side and connects to four SRAMs on the other. 4 Alliance AS7C256-15JC SRAMs Each memory has a capacity of 32KB and a 15ns access time, which allows for a maximum clock of 66 MHz. The TDS 684B supports waveform traces of 15k points, so they either only use half of the available capacity or they use some kind of double-buffering scheme. There are four unpopulated memory footprints. In one of my TDS 420A blog posts, I extend the waveform memory by soldering in extra SRAM chips. I’m not aware of a TDS 684B option for additional memory, so I’m not optimistic about the ability to expand its memory. There’s also no such grayed-out option in the acquisition menu. When googling for “ADG286D”, I got my answer when I stumbled on this comment on BlueSky which speculates that it’s an analog memory, probably some kind of CCD FIFO. Analog values are captured at a rate of up to 5 GHz and then shifted out at a much lower speed and fed into the ADC. I later found a few other comments that confirm this theory. Measuring Along the Signal Path Let’s verify this by measuring a few signals on the board with a different scope. The ADC input pins are large enough to attach a Tektronix logic analyzer probe: ADC sampling the signal With a 1 MHz signal and using a 100Msps sample rate, the input to the ADC looks like this: The input to the ADC is clearly chopped into discrete samples, with a new sample every 120 ns. We can discern a sine wave in the samples, but there’s a lot of noise on the signal too. Meanwhile the TDS684B CRT shows a nice and clean 1 MHz signal. I haven’t been able to figure out how that’s possible. For some reason, simply touching the clock pin of the ADC with a 1 MOhm oscilloscope probe adds a massive amount of noise to the input signal, but it shows the clock nicely: The ADC clock matches the input signal. It’s indeed 8.33 MHz. Acquistion refresh rate The scope only records in bursts. When recording 500, 1000 or 2500 sample points at 100Msps, it records a new burst every 14ms or 70Hz. When recording 5000 points, the refresh rate drops to 53Hz. For 15000 points, it drops even lower, to 30Hz: Sampling burst duration The duration of a sampling burst is always 2 ms, irrespective of the sample rate of the oscilloscope or the number of points acquired! The combination of a 2 ms burst and 8 MHz sample clock results in 16k samples. So the scope always acquires what’s probably the full contents of the CCD FIFO and throws a large part away when a lower sample length is selected. Here’s the 1 MHz signal sampled at 100 Msps: And here’s the same signal sampled at 5 Gsps: It looks like the signal doesn’t scan out of the CCD memory in the order it was received, hence the signal discontinuity in the middle. Sampling a 1 GHz signal I increased the input signal from 1 MHz to 1 GHz. Here’s the ADC input at 5 Gsps: With a little bit of effort, you can once again imagine a sine wave in those samples. There’s periodicity of 5 samples, as one would expect for a 1 GHz to 5 Gsps ratio. The sample rate is still 8.3 MHz. Sampling a 200 MHz signal I also applied a 200 MHz input signal. The period is now ~22 samples, as expected. 200 MHz is low enough to measure with my 350 MHz bandwidth Siglent oscilloscope. To confirm that the ADG286D chip contains the CCD memory, I measured the signal on one of the differential pins going into that chip: And here it is, a nice 200 MHz signal: A Closer Look at the Noise Issue After initially publishing this blog post, I had a discussion on Discord about the noise issue which made me do a couple more measurements. Input connected to ground Here’s what the ADC input looks like when the input of the scope is connected to ground: 2 major observations: there’s a certain amount of repetitiveness to it. there are these major voltage spikes in between each repetition. They are very faint on the scope shot. Let’s zoom in on that: The spikes are still hard to see so I added the arrows, but look how the sample pattern repeats after each spike! The time delay between each spike is ~23.6 us. With a sample rate of 120ns, that converts into a repetitive pattern of ~195 samples. I don’t know why a pattern of 195 samples exists, but it’s clear that each of those 195 locations have a fixed voltage offset. If the scope measures those offsets during calibration, it can subtract them after measurement and get a clean signal out. 50 kHz square wave Next I applied a 50kHz square wave to the input. This frequency was chosen so that, for the selected sample rate, a single period would cover the 15000 sampling points. 2 more observations: the micro-repetitiveness is still there, irrespective of the voltage offset due to the input signal. That means that subtracting the noise should be fine for different voltage inputs. We don’t see a clean square wave outline. It looks like there’s some kind of address interleaving going on. 50kHz sawtooth wave We can see the interleaving even better when applying a sawtooth wavefrom that covers one burst: Instead of a clean break from high-to-low somewhere in the middle, there is a transition period where you get both high and low values. This confirms that some kind of interleaving is happening. Conclusion The TDS684B captures input signals at high speed in an analog memory and digitizes them at 8 MHz. The single-ended input to the ADC is noisy yet the signal looks clean when displayed on the CRT of the scope, likely because the noise pattern is repetitive and predictable. In addition to noise, there’s also an interleaving pattern during the reading out of the analog FIFO contents. The number of samples digitized is always the same, irrespective of the settings in the horizontal acquisition menu. (Not written by ChatGPT, I just like to use bullet points…)
Introduction The Rohde & Schwarz AMIQ Modulation Generator WinIQSim Software Inside the AMIQ The Signal Generation PCB Analog Signal Generation Architecture: Fixed vs Variable DAC Clock Internal Reference Clock Generation DAC Clock Synthesizer I/Q Output Skew Tuning Variable Gain Amplifier Internal Diagnostics Efficient Distribution of Configuration Signals Conclusion References Introduction Every few months, a local company auctions off all kinds of lab, production and test equipment. I shouldn’t be subscribed to their email list but I am, and that’s one way I end up with more stuff that I don’t really need. During a recent auction, I got my hands on a Rohde & Schwarz AMIQ, an I/Q modulation generator, for a grand total of $45. Add to that another 30% for the auction fee and taxes and you’re still paying much less than what others would pay for a round of golf? But instead of one morning of fun, this thing has the potential to keep me busy for many weekends, so what a deal! (Click to enlarge) A few days after “winning” the auction, I drove to a dark dungeon of a warehouse in San Jose to pick up the loot. The AMIQ has a power on/off button and 3 LEDs and that’s in terms of user interface. There are no dials, there’s no display. So without any other options, I simply powered it up and I was immediately greeted by the ominous clicking of a hard drive. I was right: this thing would keep me entertained for at least a little bit! (Click to enlarge) It took a significant amount of effort to restore the machine back to its working state. I’ll write about that in future blog posts, but let’s start with an overview of the functionality and a teardown of the R&S AMIQ and then deep dive into some of its analog circuits. AMIQ prices on eBay vary wildly, from $129 to $2600 at the time of writing this. Even if you get one of the higher priced ones, you should expect to get a unit that’s close to failing due to leaking capacitors and a flaky harddrive! The Rohde & Schwarz AMIQ Modulation Generator Reduced to an elevator sales pitch, the AMIQ is a 2-channel arbitrary waveform generator (AWG) with a deep sample buffer. That’s it! It has a streaming buffer that feeds samples to 2 14-bit DACs at a sample rate of up to 105MHz. Two output channels I and Q will typically contain quadrature modulation signals that are sent to an RF vector signal generator such as a Rohde & Schwarz SMIQ for the actual high-frequency modulation. In a typical setup, the AMIQ is used to generate the baseband modulated signal and the SMIQ shifts the baseband signal to an RF frequency. Since the AMIQ has no user interface, the waveform data must provided by an external device. This could be a PC that runs R&S WinIQSim software or even the SMIQ itself because it has the ability to control an AMIQ. You can also create your own waveforms and upload them via floppy disk, GPIB or an RS-232 interface using SCPI control commands. Figure 4-1 of the AMIQ Operating Manual has a simplified block diagram. It is pretty straightforward and somewhat similar to the one of my HP 33120A function generator: (Click to enlarge) On the left are 2 blocks that are shared: a clock synthesizer waveform memory And then for each channel: 14-bit D/A converter analog filters output section with amplifier/attenuator differential analog output driver (AMIQ-B2 option) The major blocks are surrounded by a large amount of DACs that are used to control everything from the tuning input of local 10MHz clock oscillator, gain and offset of output signals, clock skew between I and Q signal and much more. You could do some of this with a modern SDR setup, but the specifications of the AMIQ units are dialed up a notch. Both channels are completely symmetrical to avoid modulation errors at the source. If there’s a need to compensate for small delay differences in, for example, the external cables, you can compensate for that by changing the skew between clocks of the output DACs with a precision of 10ps. Similarly, the DAC sample frequency can be programmed with 32-bit precision. (Click to enlarge) In addition to the main I/Q outputs at the front, there are a bunch of secondary input and output signals: 10MHz reference input and output sample clock trigger input marker output external filter loopback output and input bit error rate measurement (BER) connector (AMIQ-B1 option) parallel interface with the digital value of the samples that are sent to the DAC (front panel, AMIQ-B3 option) (Click to enlarge) Above those speciality inputs and outputs are the obligatory GPIB interface and a bunch of generic connectors that look suspiciously like the ones you’d find on an early century PC: PS/2 keyboard and mouse Parallel port RS232 USB There are 3 different AMIQ versions: 1110.2003.02: 4M samples 1110.2003.03: 4M samples 1110.2003.04: 16M samples Mine is an AMIQ-04. WinIQSim Software While it is possible to control the AMIQ over RS-232 or GPIB with your own software, you’d have a hard time matching the features of WinIQSim, a R&S Windows application that supports the AMIQ. (Click to enlarge) With WinIQSim, you can select one of the popular communication protocols from the late nineties and early 2000s, fill in digital framing data, apply all kinds of distortions and interferences, compute the I and Q waveforms and send it to the AMIQ. Some of the supported formats include CDMA2000, 802.11a WLAN, TD-SCDMA and more. But you don’t have to use these official protocols, WinIQSim supports any kind of FSK, QPSK, QAM or other common modulation method. You need a license for some of the communication protocols. The license is linked to the AMIQ device, not the PC, but the license check is pretty naive, and while I haven’t tried it… yet, the EEVblog forum has discussions about how to enable features yourself. My device only came with a license for IS-95 CDMA. Inside the AMIQ It’s trivial to open up an AMIQ: after removing the 4 feet in the back with a regular Philips screwdriver, you can simply slide off the outer case. It has 2 major subsystems: the top contains all the components of a standard PC (Click to enlarge) the bottom has a signal generation PCB (Click to enlarge) The PCB looks incredibly clean and well laid out and I love how they printed the names of different sections on the metal gray shielding plates. We’ll leave the PC system for a future blog post, and focus on the signal generation PCB. The Signal Generation PCB Let’s remove the shielding plates to see what’s underneath. I had to drill out one of the screws that attach the plates because the head was stripped. (Did somebody before me already try to repair it?) (Click to enlarge) The bottom half left and right sections are perfectly symmetrical, as one would expect for a device that has the ability to tune skew mismatches with a 10 ps precision. Annotated, it looks like this: (Click to enlarge) Rohde & Schwarz recently made the terrible decision to lock all their software and manuals behind an approval-only corporate log-in wall, but luckily some of the most important AMIQ assets can be found online elsewhere, including the operating manual and a service manual contains the full schematics! Let’s dig a bit deeper into the various aspects of the design. In what follows I’ll be focusing primarily on analog aspects of the design. This is a very personal choice: not that the digital sections aren’t important, it’s just that, as digital design engineer, they’re not particular interesting to me. By studying the analog sections, I hope to stumble into circuits that I didn’t really know a lot about before. Fantastic Schematics Before digging in for real, a word about the schematics: they are fantastic. Each sub-system has a block diagram that is already pretty detailed, with signal names that match the schematics and test points, often with annotations to indicate the voltage or frequency range. Here’s the block diagram of the reference and DAC clock generation section, for example. Schematic page 5 (Click to enlarge) Signals that come from or go to other pages are fully referenced. Look at the SYN_OUT_CLK signal below: Schematic page 10 (Click to enlarge) The signal is also used on page 6, coordinate 1D and 7B and page 22, coordinate 8A. How cool is that? Signal path test points One of the awesome features of the PCB is the generous amount of test points. We’re not just talking PCB test point against which you can hold your oscilloscope probe or even header pins, though there are plenty of those too, but full on SMB connectors. In addition to these SMD connectors, there are also plenty of jumpers that can be used to interrupt the default signal flow and insert your own test signal instead. Analog Signal Generation Architecture: Fixed vs Variable DAC Clock In the HP 33120A the DAC has a fixed 40 MHz clock. There’s a 16 kB waveform RAM that contains, say, one quarter period of a 100 Hz sine. If you want to send out a sine wave of 200 Hz, instead of sequentially stepping through all the addresses of the waveform RAM, you just skip every other address. One of the benefits of this kind of generation scheme is that you can make do with a fixed frequency analog anti-aliasing filter: the Nyquist frequency is always the same after all. A major disadvantage, however, is that even if the output signal has a bandwidth of only 1MHz, you still need to feed the DAC at the fixed clock rate. You could insert a digital upsampling filter between the waveform memory and the DAC, but that requires significant mathematical DSP fire power, or you’d have to increase the depth of the waveform memory. For an arbitrary waveform generator, it makes more sense to run the DAC at whichever clock speed is sufficient to meet the Nyquist requirement of the desired signal and provide a number of different filtering options. The AMIQ has 4 such options: no filter, a 25 MHz, a 2.5 MHz or a loopback through an external filter. The DAC sample clock range is huge, from 10 Hz all the way to 105 MHz, though specifications are only guaranteed up to 100 MHz. According to the data sheet, the clock frequency can be set with a precision of 10^-7. Internal Reference Clock Generation Like all professional test and measurement equipment, the AMIQ uses a 10MHz reference clock that can come from outside or that can be generated locally with a 10MHz crystal. It’s common for high-end equipment to have an oven controlled crystal oscillator (OCXO), but AMIQ has a lower spec’ed temperature controlled one (TCXO), a Milliren Technologies 453-0210. If we look at the larger reference clock generation block diagram, we can see something slightly unusual: instead of selecting between the internal TCXO output or the external reference clock input, the internal reference clock always comes from the TCXO (green). Schematic page 5 (Click to enlarge) When the internal clock is selected, the TCXO output frequency can be tuned with an analog signal that comes from the VTXCO TUNE DAC (blue), but when the external reference input is active, the TCXO is phase locked to the external clock. You can see the phase comparator and low pass filter in red. The reason for using a PLL with the internal TCXO as the voltage controlled oscillator is probably to ensure that the generated reference clock has the phase noise of the TCXO while tracking the frequency of the external reference clock: a PLL acts as a low-pass filter to the reference clock and as a high-pass filter to the VCO. If the TCXO has a better high frequency phase noise than the external reference clock, that makes sense. This is really out of my wheelhouse, so take all of this with a grain of salt… SYN_REF is the output of the internal reference clock generation unit. DAC Clock Synthesizer The clock synthesizer creates a highly programmable DAC clock from the internal reference clock SYN_REF from previous section. It should come as no surprise that this clock is generated by a PLL as well. Schematic page 5 (Click to enlarge) There are two speciality components in the clock generation path: a Mini-Circuits JTOS-200 VCO an Analog Devices AD9850 DDS Synthesizer (Click to enlarge) The VCO has an operating frequency between 100 and 200 MHz. I don’t know enough about VCOs to give meaningful commentary about the specifications, but based on comparisons with similar components on Digikey, such as this FMVC11009, it’s safe to assume that it’s an expensive and high quality component. The AD9850 is located in the feedback path of the PLL where it acts as a feedback divider with a precision of 32 bits. The signal flow inside the AD9850 is interesting: It works as follows: each clock cycle, the phase of a numerical controlled oscillator (NCO) accumulates with the programmable 32-bit increment. the upper bits of the phase accumulator serve as the address of a sine waveform table. a 10-bit DAC converts the digital sine wave to analog. the analog signal is sent through an external low-pass filter. the output of the low-pass filter goes back into the AD9850 and through a comparator to generate a digital output clock. This thing has its own programmable signal generator! But why the roundtrip from digital to analog back to digital? In theory, the MSB of the NCO could be used as output clock of the clock generator. The problem is that in such a configuration, the length of each clock period toggles between N and N+1 clock cycles, with a ratio so that the average clock period ends up with the desired value. But this creates major spurs in the frequency spectrum of the generated clock. When fed into the phase comparator of a PLL, these frequency spurs can show up as jitter at the output of the PLL and thus into the spectrum of the generated I and Q signals. By converting the signal to analog and using a low pass filter, the spurs can be filtered away. The combination of a low pass filter and a comparator acts as an interpolator: the edges of the generated clock fall somewhere in between N and N+1. Schematic page 21 (Click to enlarge) The steepness of the low pass filter depends on the ratio between the input and the output clock: the lower the ratio, the steeper the filter. There are a bunch of binary clock dividers that make it hard to know the exact ratio, but if the output of the VCO is 100 MHz and the input 10 MHz or less, there is a 10:1 ratio. The AMIQ has a 7th order elliptical low pass filter. I ran a quick simulation in LTspice to check the behavior. (dds_filter.asc source file.) The filter has a cut-off frequency of around 13 MHz: In modern fractional PLLs, instead of using a regular DAC, one could use a high-order sigma-delta unit to create a pulse density modulated output with the noise pushed to higher frequencies and a low pass filter that can be less aggressive. There’s a plenty of literature online about DDS clock generators, some of which I’ve listed in the references at the bottom, but the datasheet of the AD9850 itself is a good start. I/Q Output Skew Tuning Earlier I mentioned the ability to tune the skew between the I and the Q output to compensate for a difference in cable length when connecting the AMIQ to an RF signal generator. While the digital waveform fetching circuit works on one clock, the two clocks that go to the DAC are the ones that can be changed: Here’s what the skewing circuit looks like: Schematic page 10 (Click to enlarge) Starting with input signal DAC_CLK, the goal is to create I_DAC_CLK and Q_DAC_CLK that can be moved up to 1ns ahead or behind the other. Signals can be delayed by sending them through an R/C combo. Since we need a variable delay, we need a way to change the value of either the R or the C. A varactor or varicap diode is exactly that kind of device: its capacitance changes depending on the reverse bias voltage across the diode. Static input signal SKEW_TUNE comes from a DAC. It goes to the cathode of one varicap and the anode of the other. When its voltage increase, the capacitance of those 2 diodes moves in opposite ways, and so does the R/C delay along the I and Q clock path. A BB147 varicap has a capacitance that varies between 2pF and 112pF depending on the bias voltage. Capacitances C168 and C619 prevent the relatively high bias voltages from reaching the digital signal path. Does the circuit work? Absolutely! The scope photos below show the impact of the skewing circuit when dialed to the maximum in both directions: With a 2ns/div horizontal scale, you can see a skew of ~1ns either way. Variable Gain Amplifier The analog signal path starts at the DAC and then goes through the anti-aliasing filters, an output section that does amplification and attenuation, and finally the output connector board. It is common for signal generators to have a fixed gain amplification section and then some selectable fixed attenuation stages: amplifiers with a variable gain and low distortion are hard to design. If you need a signal amplitude that can’t be achieved with one of the fixed attenuation settings, one solution is to multiply the signal before it enters the DAC to reduce the output amplitude, though that’s at the expense of losing some of the dynamic range of the DAC. This is not the case for the AMIQ: while it can use a signal path that only uses fixed amplification and attenuation stages, it also offers the intriguing option to send the analog signal through an analog multiplier stage: If we zoom down from the system diagram to the block diagram, we can see how the multiplier/variable attenuator sits between the filter and the output amplifier, with 2 control input signals: AMPL_CNTRL and OFFSET. This circuit exists twice, of course, for the I and the Q channel. Schematic page 3 (Click to enlarge) Let’s check out the details! The heavy lifting of the variable gain amplifier is performed by an Analog Devices AD835 250 MHz, Voltage Output, 4-Quadrant Multiplier, a part from their Analog Multipliers & Dividers catalog. Schematic page 14 (Click to enlarge) It’s a tiny 8-pin device that calculates W = (X1-X2) * (Y1-Y2) + Z. In low volume, it will set you back $32 on Digikey. In addition to the multiplication, you can set a fixed output gain by feeding back output W through a resistive divider back into Z. For inputs less than 10 MHz, it has a typical harmonic distortion of -70dB. Analog Devices datasheets usually have a Theory of Operation section that explain, well, the underlying theory of operation. The AD835 has such a section as well, but it doesn’t go any further than stating that the multiplier is based on a classic form, having a translinear core, supported by three (X, Y, and Z) linearized voltage-to-current converters, and the load driving output amplifier. I have no clue how the thing works! In the case of the AMIQ, X2 and Y2 are strapped to ground, and there’s no feedback from W back into Z either which reduces the functionality to: W = FILTER_OUT * AMPL_VAR + OFFSET. AMPL_VAR and OFFSET are static analog values that are each created by a 12-bit DAC8143, just like many other analog configuration signals. It’s almost shame that this powerful little device is asked to perform such a basic operation. While researching the AD835, somebody pointed out the AD8310, another interesting speciality chip from Analog Devices. It’s a DC to 440 MHz, 95dB logarithmic amplifier, a converter from linear to logarithmic scale basically. Discovering little gems like this is why I love studying schematics of complex devices. Internal Diagnostics The AMIQ has a set of 15 internal analog signal to monitor the health of the device. Various meaningful signals are gathered all around the signal generation board and measured at power up to give you that dreaded Diagnostic Check Fail message. Schematic page 27 (Click to enlarge) The circuit itself is straightforward: 2 8-to-1 analog multiplexers feed into a CS5507AS 16-bit AD converter. It can only do 100 samples per second, but that’s sufficient to measure a bunch of mostly static signals. Like many other devices, the measured value is sent serially to one of the FPGAs. The ADC needs a 2.5V reference voltage. It’s funny that this reference voltage also goes to the analog multiplexers as one one of the diagnostic signals. One wonders what the ADC returns as a result when it tries to convert the output of a broken reference voltage generator. There are a bunch of circuits in the AMIQ whose only purpose is generating diagnostic signals. Here’s a good example of that: Schematic page 14 (Click to enlarge) I_OUT_DIAG and Q_OUT_DIAG are the outputs after the attenuator that will eventually end up at the connectors. The circuit in the top red square is a signal peak detector, similar to what you’d find in the rectifier of a power supply. It allows the AMIQ to track the output level of signals with a frequency that is way higher than the sample rate of the ADC. The circuit in the red rectangle below performs a digital XOR on the analog I and the Q signals and then sends it through a simple R/C low pass filter. I think that it allows the AMIQ to check that the phase difference between the I and Q channel is sensible when applying a test signal during power-on self-test. Efficient Distribution of Configuration Signals The AMIQ signal board has hundreds of configuration bits: there are the obvious enable/disable or selection bits, such as those to select between different output filters, but the lion’s share are used to set the output value of many 12-bit DACs. Instead of using parallel busses that fan out from an FPGA, the AMIQ has a serial configuration scan chain. Discrete 8-bit 74HCT4094 shift-and-store registers are located all over the design for the digital configuration bits. The DAC8134 devices have their own built-in shift register and are part of the same scan chain. Schematic page 19 (Click to enlarge) The schematic above is an example of that. The red scan chain data input goes through the VTCXO_TUNE DAC, then the 74HCT4094 after which it exist to some other page of the schematics. Conclusion Around the late nineties, test equipment companies started to stop adding schematics to their service manuals, but the R&S AMIQ is a nice exception to that. And while the device already has a bunch of FPGAs, most of the components are off-the-shelf single-function components. Thanks to that, the AMIQ is an excellent candidate for a deep dive: all the information is there, you need to just spend a bit of effort to go through things. I had a ton of fun figuring out how things worked. References Rohde & Schwarz documents R&S - IQ Modulation Generator AMIQ R&S - AMIQ Datasheet R&S - AMIQ Operating Manual R&S - AMIQ Service Manual with schematic Various application notes R&S - Floppy Disk Control of the I/Q Modulation Generator AMIQ R&S - Software WinIQSIM for Calculating I/Q Signals for Modulation Generator R&S AMIQ R&S - Creating Test Signals for Bluetooth with AMIQ / WinIQSIM and SMIQ R&S - WCDMA Signal Generator Solutions R&S - Golden devices: ideal path or detour? R&S - Demonstration of BER Test with AMIQ controlled by WinIQSIM Other AMIQ content on the web zw-ix has a blog - Getting an Rohde Schwarz AMIQ up and running zw-ix has a blog - Connecting a Rohde Schwarz AMIQ to a SMIQ04 Bosco tweets DDS Clock Synthesis MT-085 Tutorial: Fundamentals of Direct Digital Synthesis (DDS) How to Predict the Frequency and Magnitude of the Primary Phase Truncation Spur in the Output Spectrum of a Direct Digital Synthesizer (DDS) Related content The Signal Path - Teardown, Repair & Analysis of a Rohde & Schwarz AFQ100A I/Q (ARB) Modulation Generator
Introduction Selecting the RAM Opening up Replacing the RAM Reassembly References Introduction I do virtually all of my hobby and home computing on Linux and MacOS. The MacOS stuff on a laptop and almost all Linux work a desktop PC. The desktop PC has Windows on it installed as well, but it’s too much of a hassle to reboot so it never gets used in practice. Recently, I’ve been working on a project that requires a lot of Spice simulations. NGspice works fine under Linux, but it doesn’t come standard with a GUI and, more important, the simulation often refuse to converge once your design becomes a little bit bigger. Tired of fighting against the tool, I switched to LTspice from Analog Devices. It’s free to use and while it support Windows and MacOS in theory, the Mac version is many years behind the Windows one and nearly unusuable. After dual-booting into Windows too many times, a Best Buy deal appeared on my BlueSky timeline for an HP laptop for just $330. The specs were pretty decent too: AMD Ryzen 5 7000 17.3” 1080p screen 512GB SSD 8 GB RAM Full size keyboard Windows 11 Someone at the HP marketing departement spent long hours to come up with a suitable name and settled on “HP Laptop 17”. I generally don’t pay attention to what’s available on the PC laptop market, but it’s hard to really go wrong for this price so I took the plunge. Worst case, I’d return it. We’re now 8 weeks later and the laptop is still firmly in my possession. In fact, I’ve used it way more than I thought I would. I haven’t noticed any performance issues, the screen is pretty good, the SSD larger than what I need for the limited use case, and, surprisingly, the trackpad is the better than any Windows laptop that I’ve ever used, though that’s not a high bar. It doesn’t come close to MacBook quality, but palm rejection is solid and it’s seriously good at moving the mouse around in CAD applications. The two worst parts are the plasticy keyboard and the 8GB of RAM. I can honestly not quantify whether or not it has a practical impact, but I decided to upgrade it anyway. In this blog post, I go through the steps of doing this upgrade. Important: there’s a good chance that you will damage your laptop when trying this upgade and almost certainly void your warranty. Do this at your own risk! Selecting the RAM The laptop wasn’t designed to be upgradable and thus you can’t find any official resources about it. And with such a generic name, there’s guaranteed to be multiple hardware versions of the same product. To have reasonable confidence that you’re buying the correct RAM, check out the full product name first. You can find it on the bottom: Mine is an HP Laptop 17-cp3005dx. There’s some conflicting information about being able to upgrade the thing. The BestBuy Q&A page says: The HP 17.3” Laptop Model 17-cp3005dx RAM and Storage are soldered to the motherboard, and are not upgradeable on this model. This is flat out wrong for my device. After a bit of Googling around, I learned that it has a single 8GB DDR4 SODIMM 260-pin RAM stick but that the motherboard has 2 RAM slots and that it can support up to 2x32GB. I bought a kit with Crucial 2x16GB 3200MHz SODIMMs from Amazon. As I write this, the price is $44. Opening up Removing the screws This is the easy part. There are 10 screws at the bottom, 6 of which are hidden underneath the 2 rubber anti-slip strips. It’s easy to peel these stips loose. It’s als easy to put them back without losing the stickiness. Removing the bottom cover The bottom cover is held back by those annoying plastic tabs. If you have a plastic spudger or prying tool, now is the time to use them. I didn’t so I used a small screwdriver instead. Chances are high that you’ll leave some tiny scuffmarks on the plastic casing. I found it easiest to open the top lid a bit, place the laptop on its side, and start on the left and right side of the keyboard. After that, it’s a matter of working your way down the long sides at the front and back of the laptop. There are power and USB connectors that are right against the side of the bottom panel so be careful not to poke with the spudger or screwdriver inside the case. It’s a bit of a jarring process, going back and forth and making steady improvement. In addition to all the clips around the board of the bottom panel, there are also a few in the center that latch on to the side of the battery. But after enough wiggling and creaking sounds, the panel should come loose. Replacing the RAM As expected, there are 2 SODIMM slots, one of which is populated with a 3200MHz 8GDB RAM stick. At the bottom right of the image below, you can also see the SSD slot. If you don’t enjoy the process of opening up the laptop and want to upgrade to a larger drive as well, now would be the time for that. New RAM in place! It’s always a good idea to test the surgery before reassembly: Success! Reassembly Reassembly of the laptop is much easier than taking it apart. Everything simply clicks together. The only minor surprise was that both anti-slip strips became a little bit longer… References Memory Upgrade for HP 17-cp3005dx Laptop Upgrading Newer HP 17.3” Laptop With New RAM And M.2 NVMe SSD Different model with Intel CPU but the case is the same.
More in technology
There are a handful of instruments that are staples of modern music, like guitars and pianos. And then there are hundreds of other instruments that were invented throughout history and then fell into obscurity without much notice. The Luminaphone, invented by Harry Grindell Matthews and unveiled in 1925, is a particularly bizarre example. Few people […] The post Recreating a bizarre century-old electronic instrument appeared first on Arduino Blog.
Sometimes I think I should pivot my career to home automation critic, because I have many opinions on the state of the home automation industry---and they're pretty much all critical. Virtually every time I bring up home automation, someone says something about the superiority of the light switch. Controlling lights is one of the most obvious applications of home automation, and there is a roughly century long history of developments in light control---yet, paradoxically, it is an area where consumer home automation continues to struggle. An analysis of how and why billion-dollar tech companies fail to master the simple toggling of lights in response to human input will have to wait for a future article, because I will have a hard time writing one without descending into incoherent sobbing about the principles of scene control and the interests of capital. Instead, I want to just dip a toe into the troubled waters of "smart lighting" by looking at one of its earliest precedents: low-voltage lighting control. A source I generally trust, the venerable "old internet" website Inspectapedia, says that low-voltage lighting control systems date back to about 1946. The earliest conclusive evidence I can find of these systems is a newspaper ad from 1948, but let's be honest, it's a holiday and I'm only making a half effort on the research. In any case, the post-war timing is not a coincidence. The late 1940s were a period of both rapid (sub)urban expansion and high copper prices, and the original impetus for relay systems seems to have been the confluence of these two. But let's step back and explain what a relay or low-voltage lighting control system is. First, I am not referring to "low voltage lighting" meaning lights that run on 12 or 24 volts DC or AC, as was common in landscape lighting and is increasingly common today for integrated LED lighting. Low-voltage lighting control systems are used for conventional 120VAC lights. In the most traditional construction, e.g. in the 1940s, lights would be served by a "hot" wire that passed through a wall box containing a switch. In many cases the neutral (likely shared with other fixtures) went directly from the light back to the panel, bypassing the switch... running both the hot and neutral through the switch box did not become conventional until fairly recently, to the chagrin of anyone installing switches that require a neutral for their own power, like timers or "smart" switches. The problem with this is that it lengthens the wiring runs. If you have a ceiling fixture with two different switches in a three-way arrangement, say in a hallway in a larger house, you could be adding nearly 100' in additional wire to get the hot to the switches and the runner between them. The cost of that wiring, in the mid-century, was quite substantial. Considering how difficult it is to find an employee to unlock the Romex cage at Lowes these days, I'm not sure that's changed that much. There are different ways of dealing with this. In the UK, the "ring main" served in part to reduce the gauge (and thus cost) of outlet wiring, but we never picked up that particular eccentricity in the US (for good reason). In commercial buildings, it's not unusual for lighting to run on 240v for similar reasons, but 240v is discouraged in US residential wiring. Besides, the mid-century was an age of optimism and ambition in electrical technology, the days of Total Electric Living. Perhaps the technology of the relay, refined by so many innovations of WWII, could offer a solution. Switch wiring also had to run through wall cavities, an irritating requirement in single-floor houses where much of the lighting wiring could be contained to the attic. The wiring of four-way and other multi-switch arrangements could become complex and require a lot more wall runs, discouraging builders providing switches in the most convenient places. What if relays also made multiple switches significantly easier to install and relocate? You probably get the idea. In a typical low-voltage lighting control system, a transformer provides a low voltage like 24VAC, much the same as used by doorbells. The light switches simply toggle the 24VAC control power to the coils of relays. Some (generally older) systems powered the relay continuously, but most used latching relays. In this case, all light switches are momentary, with an "on" side and an "off" side. This could be a paddle that you push up or down (much like a conventional light switch), a bar that you push the left or right sides of, or a pair of two push buttons. In most installations, all of the relays were installed together in a single enclosure, usually in the attic where the high-voltage wiring to the actual lights would be fairly short. The 24VAC cabling to the switches was much smaller gauge, and depending on the jurisdiction might not require any sort of license to install. Many systems had enclosures with separate high voltage and low voltage components, or mounted the relays on the outside of an enclosure such that the high voltage wiring was inside and low voltage outside. Both arrangements helped to meet code requirements for isolating high and low voltage systems and provided a margin of safety in the low voltage wiring. That provided additional cost savings as well; low voltage wiring was usually installed without any kind of conduit or sheathed cable. By 1950, relay lighting controls were making common appearances in real estate listings. A feature piece on the "Melody House," a builder's model home, in the Tacoma News Tribune reads thus: Newest features in the house are the low voltage touch plate and relay system lighting controls, with wide plates instead of snap buttons---operated like the stops of a pipe organ, with the merest flick of a finger. The comparison to a pipe organ is interesting, first in its assumption that many readers were familiar with typical organ stops. Pipe organs were, increasingly, one of the technological marvels of the era: while the concept of the pipe organ is very old, this same era saw electrical control systems (replete with relays!) significantly reduce the cost and complexity of organ consoles. What's more, the tonewheel electric organ had become well-developed and started to find its way into homes. The comparison is also interesting because of its deficiencies. The Touch-Plate system described used wide bars, which you pressed the left or right side of---you could call them momentary SPDT rocker switches if you wanted. There were organs with similar rocker stops but I do not think they were common in 1950. My experience is that such rocker switch stops usually indicate a fully digital control system, where they make momentary action unobtrusive and avoid state synchronization problems. I am far from an expert on organs, though, which is why I haven't yet written about them. If you have a guess at which type of pipe organ console our journalist was familiar with, do let me know. Touch-Plate seems to have been one of the first manufacturers of these systems, although I can't say for sure that they invented them. Interestingly, Touch-Plate is still around today, but their badly broken WordPress site ("Welcome to the new touch-plate.com" despite it actually being touchplate.com) suggests they may not do much business. After a few pageloads their WordPress plugin WAF blocked me for "exceed[ing] the maximum number of page not found errors per minute for humans." This might be related to my frustration that none of the product images load. It seems that the Touch-Plate company has mostly pivoted to reselling imported LED lighting (touchplateled.com), so I suppose the controls business is withering on the vine. The 1950s saw a proliferation of relay lighting control brands, with GE introducing a particularly popular system with several generations of fixtures. Kyle Switch Plates, who sell replacement switch plates (what else?), list options for Remcon, Sierra, Bryant, Pyramid, Douglas, and Enercon systems in addition to the two brands we have met so far. As someone who pays a little too much attention to light switches, I have personally seen four of these brands, three of them still in use and one apparently abandoned in place. Now, you might be thinking that simply economizing wiring by relocating the switches does not constitute "home automation," but there are other features to consider. For one, low-voltage light control systems made it feasible to install a lot more switches. Houses originally built with them often go a little wild with the n-way switching, every room providing lightswitches at every door. But there is also the possibility of relay logic. From the same article: The necessary switches are found in every room, but in the master bedroom there is a master control panel above the bed, from where the house and yard may be flooded with instant light in case of night emergency. Such "master control panels" were a big attraction for relay lighting, and the finest homes of the 1950s and 1960s often displayed either a grid of buttons near the head of the master bed, or even better, a GE "Master Selector" with a curious system of rotary switches. On later systems, timers often served as auxiliary switches, so you could schedule exterior lights. With a creative installer, "scenes" were even possible by wiring switches to arbitrary sets of relays (this required DC or half-wave rectified control power and diodes to isolate the switches from each other). Many of these relay control systems are still in use today. While they are quite outdated in a certain sense, the design is robust and the simple components mean that it's usually not difficult to find replacement parts when something does fail. The most popular system is the one offered by GE, using their RR series relays (RR3, RR4, etc., to the modern RR9). That said, GE suggests a modernization path to their LightSweep system, which is really a 0-10v analog dimming controller that has the add-on ability to operate relays. The failure modes are mostly what you would expect: low voltage wiring can chafe and short, or the switches can become stuck. This tends to cause the lights to stick on or off, and the continuous current through the relay coil often burns it out. The fix requires finding the stuck switch or short and correcting it, and then replacing the relay. One upside of these systems that persists today is density: the low voltage switches are small, so with most systems you can fit 3 per gang. Another is that they still make N-way switching easier. There is arguably a safety benefit, considering the reduction in mains-voltage wire runs. Yet we rarely see such a thing installed in homes newer than around the '80s. I don't know that I can give a definitive explanation of the decline of relay lighting control, but reduced prices for copper wiring were probably a main factor. The relays added a failure point, which might lead to a perception of unreliability, and the declining familiarity of electricians means that installing a relay system could be expensive and frustrating today. What really interests me about relay systems is that they weren't really replaced... the idea just went away. It's not like modern homes are providing a master control panel in the bedroom using some alternative technology. I mean, some do, those with prices in the eight digits, but you'll hardly ever see it. That gets us to the tension between residential lighting and architectural lighting control systems. In higher-end commercial buildings, and in environments like conference rooms and lecture halls, there's a well established industry building digital lighting control systems. Today, DALI is a common standard for the actual lighting control, but if you look at a range of existing buildings you will find everything from completely proprietary digital distributed dimming to 0-10v analog dimming to central dimmer racks (similar to traditional theatrical lighting). Relay lighting systems were, in a way, a nascent version of residential architectural lighting control. And the architectural lighting control industry continues to evolve. If there is a modern equivalent to relay lighting, it's something like Lutron QSX. That's a proprietary digital lighting (and shade) control system, marketed for both residential and commercial use. QSX offers a wide range of attractive wall controls, tight integration to Lutron's HomeSense home automation platform, and a price tag that'll make your eyes water. Lutron has produced many generations of these systems, and you could make an argument that they trace their heritage back to the relay systems of the 1940s. But they're just priced way beyond the middle-class home. And, well, I suppose that requires an argument based on economics. Prices have gone up. Despite tract construction being a much older idea than people often realize, it seems clear that today's new construction homes have been "value engineered" to significantly lower feature and quality levels than those of the mid-century---but they're a lot bigger. There is a sort of maxim that today's home buyers don't care about anything but square footage, and if you've seen what Pulte or D. R. Horton are putting up... well, I never knew that 3,000 sq ft could come so cheap, and look it too. Modern new-construction homes just don't come with the gizmos that older ones did, especially in the '60s and '70s. Looking at the sales brochure for a new development in my own Albuquerque ("Estates at La Cuentista"), besides 21st century suburbanization (Gated Community! "East Access to Paseo del Norte" as if that's a good thing!) most of the advertised features are "big." I'm serious! If you look at the "More Innovation Built In" section, the "innovations" are a home office (more square footage), storage (more square footage), indoor and outdoor gathering spaces (to be fair, only the indoor ones are square footage), "dedicated learning areas" for kids (more square footage), and a "basement or bigger garage" for a home gym (more square footage). The only thing in the entire innovation section that I would call a "technical" feature is water filtration. You can scroll down for more details, and you get to things like "space for a movie room" and a finished basement described eight different ways. Things were different during the peak of relay lighting in the '60s. A house might only be 1,600 sq ft, but the builder would deck it out with an intercom (including multi-room audio of a primitive sort), burglar alarm, and yes, relay lighting. All of these technologies were a lot newer and people were more excited about them; I bring up Total Electric Living a lot because of an aesthetic obsession but it was a large-scale advertising and partnership campaign by the electrical industry (particularly Westinghouse) that gave builders additional cross-promotion if they included all of these bells and whistles. Remember, that was when people were watching those old videos about the "kitchen of the future." What would a 2025 "Kitchen of the Future" promotional film emphasize? An island bigger than my living room and a nook for every meal, I assume. Features like intercoms and even burglar alarms have become far less common in new construction, and even if they were present I don't think most buyers would use them. But that might seem a little odd, right, given the push towards home automation? Well, built-in home automation options have existed for longer than any of today's consumer solutions, but "built in" is a liability for a technology product. There are practical reasons, in that built-in equipment is harder to replace, but there's also a lamer commercial reason. Consumer technology companies want to sell their products like consumer technology, so they've recontextualized lighting control as "IoT" and "smart" and "AI" rather than something an electrician would hook up. While I was looking into relay lighting control systems, I ran into an interesting example. The Lutron Lu Master Lumi 5. What a name! Lutron loves naming things like this. The Lumi 5 is a 1980s era product with essentially the same features as a relay system, but architected in a much stranger way. It is, essentially, five three way switches in a box with remote controls. That means that each of the actual light switches in the house (which could also be dimmers) need mains-voltage wiring, including runner, back to the Lumi 5 "interface." Pressing a button on one of the Lutron wall panels toggles the state of the relay in the "interface" cabinet, toggling the light. But, since it's all wired as a three-way switch, toggling the physical switch at the light does the same thing. As is typical when combining n-way switches and dimming, the Lumi 5 has no control over dimmers. You can only dim a light up or down at the actual local control, the Lumi 5 can just toggle the dimmer on and off using the 3-way runner. The architecture also means that you have two fundamentally different types of wall panels in your house: local switches or dimmers wired to each light, and the Lu Master panels with their five buttons for the five circuits, along with "all on" and "all off." The Lumi 5 "interface" uses simple relay logic to implement a few more features. Five mains-voltage-level inputs can be wired to time clocks, so that you can schedule any combination(s) of the circuits to turn on and off. The manual recommends models including one with an astronomical clock for sunrise/sunset. An additional input causes all five circuits to turn on; it's suggested for connection to an auxiliary relay on a burglar alarm to turn all of the lights on should the alarm be triggered. The whole thing is strange and fascinating. It is basically a relay lighting control system, like so many before it, but using a distinctly different wiring convention. I think the main reason for the odd wiring was to accommodate dimmers, an increasingly popular option in the 1980s that relay systems could never really contend with. It doesn't have the cost advantages of relay systems at all, it will definitely be more expensive! But it adds some features over the fancy Lutron switches and dimmers you were going to install anyway. The Lu Master is the transitional stage between relay lighting systems and later architectural lighting controls, and it straddled too the end of relay light control in homes. It gives an idea of where relay light control in homes would have evolved, had the whole technology not been doomed to the niche zone of conference centers and universities. If you think about it, the Lu Master fills the most fundamental roles of home automation in lighting: control over multiple lights in a convenient place, scheduling and triggers, and an emergency function. It only lacks scenes, which I think we can excuse considering that the simple technology it uses does not allow it to adjust dimmers. And all of that with no Node-RED in sight! Maybe that conveys what most frustrates me about the "home automation" industry: it is constantly reinventing the wheel, an oligopoly of tech companies trying to drag people's homes into their "ecosystem." They do so by leveraging the buzzword of the moment, IoT to voice assistants to, I guess now AI?, to solve a basic set of problems that were pretty well solved at least as early as 1948. That's not to deny that modern home automation platforms have features that old ones don't. They are capable of incredibly sophisticated things! But realistically, most of their users want only very basic functionality: control in convenient places, basic automation, scenes. It wouldn't sting so much if all these whiz-bang general purpose computers were good at those tasks, but they aren't. For the very most basic tasks, things like turning on and off a group of lights, major tech ecosystems like HomeKit provide a user experience that is significantly worse than the model home of 1950. You could install a Lutron system, and it would solve those fundamental tasks much better... for a much higher price. But it's not like Lutron uses all that money to be an absolute technical powerhouse, a center of innovation at the cutting edge. No, even the latest Lutron products are really very simple, technically. The technical leaders here, Google, Apple, are the companies that can't figure out how to make a damn light switch. The problem with modern home automation platforms is that they are too ambitious. They are trying to apply enormously complex systems to very simple tasks, and thus contaminating the simplest of electrical systems with all the convenience and ease of a Smart TV. Sometimes that's what it feels like this whole industry is doing: adding complexity while the core decays. From automatic programming to AI coding agents, video terminals to Electron, the scope of the possible expands while the fundamentals become more and more irritating. But back to the real point, I hope you learned about some cool light switches. Check out the Kyle Switch Plates reference and you'll start seeing these buildings and homes, at least if you live in an area that built up during the era that they were common (1950s to the 1970s).
Is there anything more irritating than living with a partner who procrastinates on their share of the chores? Even if it isn’t malicious, it sure is annoying. Taking out the trash is YouTuber CircuitCindy’s boyfriend’s responsibility, but he often fails to do the task in a timely manner. That forced Cindy to implement a sinister […] The post YouTuber builds robot to make boyfriend take out the trash appeared first on Arduino Blog.