Tag Archives | Logic


Working Relay BCD Decoder

  Been a while since I posted on this subject. I have had the PCB fabricated and assembled one BCD controller. It tool a long time to solder in all the parts, but eventually it got built. After some initial testing of the PCB I found that I had messed up ONE circuit, the one […]

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logic friday screen shot

BCD Decoder Logic

7 Segment decoder full truth table. Note that RBI’ segment decoders are exactly the same except in the A=B=C=D=0 condition Here is my original truth table for the encoder. It features 7 segmenmt decoding of a BCD input from 0-9. It also features Ripple Blanking input and output much like the standard TTL Decoders of […]

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Relay AND Logic

Relay Logic Diagrams

Here is the start of the 7 Segment BCD decoder logic. The idea is to make a generic board that can decode BCD data and display like a LED Digit might. This is similar to the 7447 (or many variants). This post will show the general Relay based logic that I will be using. AND, […]

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EZ260 Tube Amplifiers and Tube Projects