Hi guys, I’m new here and also new in the wolrd of DIY electronics, I’ve been designing a “drone synth” based in the 40106 CMOS chip, heavily inspired in some of the videos of ObserverB channel and website, I just wanted to know if this think would work, I’m currently putting everything together in a protoboard, so let’s see how this works, Lmk if this design is any good or if I should change anything.
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This is wrong:
You have the 9V rail shorted to ground. What you presumably want is for the junction between the two resistors to connect to the op amp. Also you have capacitors in series on the power and ground rails and that isn’t correct. There should be two capacitors from 9 V to ground, one placed near the 40106 power pin and one near the TL074 power pin.
I don’t understand this:
This would I think work as coarse and fine tuning knobs if the pots were set up as variable resistors, but the connection to ground makes them voltage dividers — connected in a way I don’t think makes sense. I think pins 3 should be connected to pins 2, not to ground and not to each other.
The sleeve of J2 is not connected to ground, so something’s wrong there.
Stylistically, I recommend instead of running lines from all over to a single ground symbol, instead use multiple ground symbols; it’s easier to understand that way. Also KiCad does have vactrol symbols
Finally, making the circuit on a solderless breadboard before soldering something up is a good idea.
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You still have +9 V shorted to ground. You still have capacitors in series on the 9 V rail instead of from the power pins to ground.
Analog Output in his first sentence refers to the link between the junctions under R13 and above R12. It makes a direct connection between +9V and GND.
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Thank you guys for all the tips! Changed the +9V for a battery on the schematic since it’s going to be battery powrd, Would it be something like this better ?
This isn’t good either, put one resistor in series with each LED.
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yes.
Values may have to be adjusted depending on the LEDs(too bright or too dim)
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Maybe not strictly necessary — at least if the two LEDs have similar forward voltage. But it’ll limit the current through the higher voltage one maybe making it very much dimmer. Anyway, two resistors is good because it means you can tune the brightnesses of the two LEDs separately. Which you definitely should do, and it’s much more easily done on a breadboard than in a soldered prototype.
This doesn’t look right either. I assume that you are trying to make a voltage divider to provide a voltage reference for the single supply op amps. Instead, you are grounding the reference voltage… To correct this, you should have an electrolytic capacitor (say 47μF) from that junction, that I circled, to ground.
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Here’s a pretty good tutorial on voltage dividers.
But the really basic thing is, you can’t connect voltage sources together, and ground is a voltage source. So you can’t connect +9 V to ground, as in your first version, or the output of your voltage divider to ground, as in your most recent. In the first case you’re shorting out your power supply and the best outcome is nothing works. (The worst outcome is you start a fire.) In the second case, since the voltage source has a 4.7k impedance, when it gets in a fight with a direct connection to ground it loses, and you get zero volts where you’re expecting +4.5 V. No fires started this time, but again, it won’t work.
Oh, also:
You have ground symbols but none actually connect to the thing that establishes what ground is, which is the battery. Add a ground symbol connecting to that bottom line, which connects to the battery’s negative terminal.
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