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Revision as of 15:22, 22 May 2007
Aloha from Honolulu, I found Open Circuits on or about May 15, 2007. I was searching the internet for "electronic breadboard" and found SparkFun Electronics which has a link to Open Circuits.
I have an idea for some "building block" circuit boards that engineers and students can use for breadboarding. I just happen to need something like this myself, so maybe others can use them too. I couldn't find anything like I have in mind, so perhaps there is a market waitng to be created. I'd be happy to share the scematics and artwork (once they exist) and hope that others will share their ideas. Eventualy we could build a library of these that colleges and tech schools would use.
So that is how I came to Open Circuits. It also happened to be at a time when I had just completed a project that had been hanging fire for several years. That is the artwork for some voltage regulator boards based on the LM723 IC. I have used these in several personal projects and also in some professional ones.
My main gig here in Honolulu has been the installation and servicing of recording studios. I've been at it for the past 20 years. I had one client whose console power supply needed help. The voltage regulators were a high current (7 amp) device in a TO3 package. There was one each for the +15V and -15V rails. I'd replaced them once before, but this time I could not find the devices. (I forgot what the part number was.) So I decided to use a couple of LM723s which I had a large supply of (courtesy of another project that had not gotten off the ground). I used a 2N3055 transistor as the external series pass element for the positive side and tried to use its compliment 2N2955 for the negative side. But I found I could not get the current required. I switched to a Darlington device and the problem went away, so I used a complimentary pair of 15 amp Darlington transistors in TO3 packages. The unit has now been working for nearly 10 years. I plan to share these designs here once I have a better understanding of how to upload files and what formats to use.
My other interests are in embedded processors and computer programming. I used to do a lot with Pascal and Assembly back in the DOS days. I started with Turbo Pascal 3 and Turbo Assembler, I went up to Turbo Pascal version 7 before Windows came along and made it more complicated. I started to learn C++, but got out of programming for several years. I got back into it again when embedded devices started to proliferate. I brushed off my C++, but find I'm mostly using plain C with these things. That and Assembly when something needs to go as fast as it can.
I'll continue with this as time allows.
RAF 17:45, 18 May 2007 (PDT)
Hello again, I fiished my article as well as another article I want to include. The second is not mine, but is so old I can't find it anywhere, but for the copy I have in my files. The title is: "The Many-Talented 723" and the author is Glenn Prescott. I've searched the web without finding any reference to it. I have a xerox copy from the mid 1980s. Not a very good copy, but I scanned it and ran an OCR program on it. I still had to do a lot of editing to help out the OCR. Then I had to do all the images over again myself. I kept them as close to the originals as I could, except for scale, mine are a little larger and this more legible. My text is also full page instead of the 4 column format of the original. So now I'm ready to put this all together. I uploaded a symbol for the image of the 723. Otherwise it would be a picture of a 14-pin DIP. I'm going to see if I can copy it to this page... RAF