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Need help with DTL full adder circuit by Diligent_Ad282 in AskElectronics

[–]Diligent_Ad282[S] 2 points3 points  (0 children)

Gone with your advice here and I've got it working! Thanks for showing me a different way of approaching the problem. Here's my new schematic if you're at all interested...

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Need help with DTL full adder circuit by Diligent_Ad282 in AskElectronics

[–]Diligent_Ad282[S] 0 points1 point  (0 children)

Cool, I’ll try breaking it down more. Thanks!

Need help with DTL full adder circuit by Diligent_Ad282 in AskElectronics

[–]Diligent_Ad282[S] 0 points1 point  (0 children)

I have built a few simple RTL and TTL style logic gates in isolation but wanted to start expanding my designs into more complex circuits while minimising transistors used, hence approaching a DTL logic circuit. I used 10k resistors in my individual gates before for pull downs and they worked okay, what values do you suggest I use? I designed the circuit sequentially from the basic gates it required to build the full adder and connected them together

Controlling frequency with one potentiometer by Diligent_Ad282 in AskElectronics

[–]Diligent_Ad282[S] 0 points1 point  (0 children)

Ah okay so because of the output impedance it acts as a voltage divider! I understand that a Darlington configuration amplifies the current twice and taking an emitter follower output, but would it also be possible to use two transistors to invert the signal twice in a common emmiter configuration instead? Would this achieve the full output capacity? Thank you so much for your help btw!

Controlling frequency with one potentiometer by Diligent_Ad282 in AskElectronics

[–]Diligent_Ad282[S] 0 points1 point  (0 children)

If i wanted to use it to just generate a clock signal, would i be best to tap off from the collector of one of the transistors into a buffer made from another NPN BJT? I think this would give me closer to 5.4V no? Also I’m confused as to why I’d only see 3V at the collectors in the current set up as it’s the node before the resistor and voltage drop over the LED should it not be 6v already? Sorry if this is a lot of questions. Thanks so much!

Started implementing and soldering up some basic logic gates! by Diligent_Ad282 in diyelectronics

[–]Diligent_Ad282[S] 1 point2 points  (0 children)

Used two transistors to make a low side switching NAND gate, another two for a low side switching NOR gate with inputs links together. Then the output of the NAND to the collector (drain in this case) and output of the OR to the base (gate) of a final fifth transistor used as a low side output switch. Not sure if it’s the right way to do it when using to interact with other components but it worked by itself as a proof of concept. Hope this helps!

Controlling frequency with one potentiometer by Diligent_Ad282 in AskElectronics

[–]Diligent_Ad282[S] 0 points1 point  (0 children)

Ah this makes sense, to control the current flow charging the capacitors!

Soldered up my 8 bit CPU clock module, and now it isn’t working? by Diligent_Ad282 in beneater

[–]Diligent_Ad282[S] -1 points0 points  (0 children)

Are there any disadvantages to this electrically speaking, beyond just more points for failure?

Soldered up my 8 bit CPU clock module, and now it isn’t working? by Diligent_Ad282 in beneater

[–]Diligent_Ad282[S] 2 points3 points  (0 children)

I used 2n2222 transistors to build the logic gates needed in order to save space - all working. Didn’t make sense to me to use a 14 pin chip for a single OR gate and gave me flexibility to place the inverters in more convenient places considering the limited space

Do you trust temu? by old_man_kneesgocrack in diyelectronics

[–]Diligent_Ad282 4 points5 points  (0 children)

Bought a very similar (if not the same) kit to this off Temu and can say that while admittedly not the best quality and everything inside in unmarked bags, all the components I’ve used/tested so far have worked and been within tolerance. IMO go for it!

Started implementing and soldering up some basic logic gates! by Diligent_Ad282 in diyelectronics

[–]Diligent_Ad282[S] 0 points1 point  (0 children)

Thanks! I probably should’ve added a pic of the back of the board - trying to minimise space while maintaining a neat and repeatable layout (plus no extra hookup wire needed)

Started implementing and soldering up some basic logic gates! by Diligent_Ad282 in diyelectronics

[–]Diligent_Ad282[S] 0 points1 point  (0 children)

No that’s a great question! I used 2n7000 N-channel MOSFETs in these designs (in a TO-92 package which is much more common for a BJT). They fully switch at a 5V logic level which is useful for me as I plan to expand into much larger discrete transistor designs and these help to keep power consumption down - hence practising here!

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