I can certainly do that and I appreciate your interest.
Nostalgia perhaps. I remember learning about R-2R ladder networks in the 1960s when we did everything with discrete logic. Large-scale-integration (LSI) of TTL was just beginning, CMOS logic was pie-in-the-sky, and if you wanted a DAC or ADC it had to be roll-your-own or purchase an expensive hybrid or even more expensive hybrid data acquisition module.
I really drooled when Burr-Brown came out with a multiplying DAC in the mid 1970s and TI offered 1 K-bit SRAM ICs. Intel was just getting started making microprocessors and hobbiests with deep pockets had started to pick up on that. This was the hey-day of TTL, so I used the DAC and ten of the RAM chips to build a multiplying digital function generator (MDFG) for a customer at Wright-Patterson AFB. The MDFG was used to linearize the spectral response of a monochrometer/photo-multiplier tube, visible light, transmission absorption-measuring system. Our tax dollars at work of course.
Last year I found the monochrometer scrapped and for sale at Mendelson Electronics. I tried to buy it (not that I had any use for it), offering them $25. No sale. Instead they immediately got online and Googled monochrometers and found it was worth much more than that to anyone who needed one. I should have kept my mouth shut about it being a monochrometer and instead told them I was only slightly interested in the mirrors inside... one of which was a large focusing diffraction grating that sold for several thousand dollars when it was new.
And I did find an app note where discrete transistors were suggested to switch in resistors for binary control of a three-terminal adjustable regulator. But I seem to recall that at one time you could purchase a device (maybe a hybrid?) that had the switches and a TTL interface built-in. Probably obsolete now...
Many years ago I heard of a cell phone that they stopped selling because it didn't break. As we all know most or many companies design their products to last past the warranty and then hopefully break soon after
Yeah, I had to replace a large window air conditioner a few years ago that quit working. I fixed it once when the motor-starting capacitor failed and I was able to locate a replacement part... not an exact replacement; the one I found was larger and had to be mounted outboard with extension wires. That worked for one season. Then the bearings in the common shaft for the evaporator fan and condenser fan failed because they rusted out and there was no provision for lubricating them. Bad design that, exposing the bearings to the elements so they could rust and fail. Or maybe that was the intent. Nothing wrong with the air conditioning components. No leaks. Compressor worked fine. But out of warranty as you said. Everything inside was made in China.
It's kind of funny how suddenly the big hype came out about LEDs, how they are the latest and greatest even though the rest of us have been dealing with them since like 15 years ago. I definitely remember when white and blue LEDs came out, that was cool, but at ~$3 a pop I couldn't even afford them haha.
I do remember that. I bought a TI four-function desk calculator with tiny red LED seven-segment displays when they first appeared and I was earning big bucks. I once even owned a wrist-watch with a tiny red seven-segment LED display (totally impractical). It was many years later that colored LEDs (green, orange/yellow, and red) became somewhat affordable, and much later than that (after UV LEDs were developed) that efficient white-light LEDs finally became practical and affordable.
Lately I have been converting many lamps in my house to LEDs. Not all! I like the warm glow of incandescent lamps, and they are easier to dim. Some of these LED replacements didn't last very long because they overheated in their fixture and the electronics failed. I just recently replaced some of the fluorescent fixtures that I installed forty years ago in my basement workshop areas. Their electro-magnetic ballasts have failed. The new ones use the smaller T4 tubes and electronic ballasts, but the laundry room down there now has LED luminaries. My wife hates fluorescent lamps.
Please return here and let us know how your motor control project turned out. If it's not proprietary, there is a forum area here just for showing off that sort of thing.
Hop
