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I'm trying to build a half adder with soft-latching buttons as input, using only transistors. I looked up online for some ideas and managed to build a soft-latching input circuit and a half adder circuit on a breadboard. Separately they worked, but the output LED was dimmer than I expected. However, once I assembled the whole thing together, it seemed not to be working at all. I'm guessing that the current levels are too low to drive the components properly. With the breadboard I used a 3.2V battery.

Below is the design that I came up with. I'm not sure if it just missing some details or if I got the design fundamentally wrong. I would appreciate any hints or maybe recommendation for some reading that could help me understand this better.

Circuit

Edit

I applogize about the earlier schematic, here is one that I created earlier with Eagle, hopefully that will be better. enter image description here

Rafał
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    Now that's a schematic I absolutely must save as an example of why one needs to learn how to draw! Anyway, look at this RTL XNOR and, more closely to what you want, this RTL Full-Adder Design Process. – jonk May 26 '20 at 14:41
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    Rafal, simple rule: when drawing a schematic, use horizontal and vertically aligned components only, This schematic is a mess. Also, a schematic needs to show compnent names. How else will we talk about it? "The 1 kΩ resistor blablabla" isn't really helpful. – Marcus Müller May 26 '20 at 15:08
  • What are those little open circle components? Why didn't you use 5V as shown on the schematic? – Elliot Alderson May 26 '20 at 19:32
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    I've updated the question with a more appropriate schematic. I used CircuitJS1 to try to understand better what was going on with the design and circles is how it represents LED (the inside changes colour when it's on). – Rafał May 26 '20 at 23:29

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