Welcome to another installment in the SUHL series. This video will focus on the SG-222 and SG-223, but will also revisit one of the unknown components from the previous video.
After the last video where I was unable to determine the parts that I had, I set out to find a part that was included in the Sylvania databook, hoping that it would be easier to decode a circuit that I knew 100% what it was. I found a handful of different SUHL chips on Ebay, some in the databook and some not, but ended up buying them all. Since the unidentified chip had 220 on the silicon, I decided to start with the SG-222 and SG-223, since they are cross-listed under the SG-220 in the databook.
Since I had the diagrams in the databook for these parts, they were rather straightforward to follow. I was able to successfully trace out these circuits, and even simulate them in LTspice to confirm their functionality. One thing I thought to do that didn’t occur to me previously was to just hook the parts up and measure the outputs when various inputs were applied. I was able to confirm with voltages applied that the SG-222 and SG-223 are in fact quad 2-input NAND gates.
With my newfound circuit analysis knowledge, I applied what I had learned from the 222 & 223 to the previous circuit marked 220 on the silicon. This part ended up being a Triple three-input NOR chip. I was also able to confirm this in both simulation and by applying different inputs and measuring the outputs. The truth tables that I built matched exactly with a NOR’s truth table.
I have many more different SUHL parts that I plan to analyze like this in the future. I’m looking forward to building on my circuit analysis skills and improving them with each chip that I open. Some of them are pretty old and I’m looking forward to seeing what they look like.
*** Huge thanks to @ringoware on Twitter for assisting with parts of the circuit analysis that I initially had wrong. **
Sources used in the video:
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Bitsavers .org PDF link:
www.bitsavers.org/components/s...
Diagrams created with the use of Inkscape:
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✒️ inkscape.org/
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