- The oscillator works
- Both oscillators work. I did the vactrol with an LDR and an LED and made made everything dark with insulation tape (which also holds them together)
- Unfortunately idk the value of the LED, is there a way to test it? (I’m using the same red LED that u see in the picture)
- I’ m using a 470 Ohm resistor, the LFO is basically the second oscillator, the capacitor is 470 uF. The overall circuit is powered with 18v.
Here is a picture of the circuit but it’ s super messy, not sure whether it can help or not. The oscillator that I want to modulate is the one with the green LED, the LFO is the red one
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with what you say it’s seems good, with the pic is difficult !
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remove the vactrol
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take juste the LDR and put it on the pitch pot of the first osc, and test it with a light (your phone for exemple) and your hand for hide the LDR
for testing the LDR like that you must put the pot to zero (completely at the left when you are in front off the knob = low pitch
the light must do the same thing like when you turn the pot to the right (the pitch more high)
test only that and say me if it’s ok
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Works when I only use the LDR! But it doesn’t when I try to plug the rest again
- test only the led (+ resistor) without the LDR
if your led bright test that
( if not try another led maybe it dead (or you put it upside down +/- or the resistor was not strong enough do it with 1k)
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Did that! The LED lights up and pulsates but it’s extremely dim. Might be that because of that the LDR doesn’t receive enough light. All of a sudden I started hearing a very high pitched noise coming from the power jack and teh thing made a small pop 
might be wise to wait until tomorrow!
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in these cases right away quickly unplug the curent
be careful not to set fire
can you send a pic of your power socket side plz ?
Like this?
The power comes directly from a 18V power supply plugged into the wall. Nothing seems damaged, I just hope that it didn’ t blow all the components in the circuit
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I hope too !
maybe crocodile plugs that touched together during the test
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Mmm I don’ t think so because I tried to change the socket and it did the same thing. I think it comes from the power supply, which I left plugged for days (I was just unplugging the wire carrying positive signal to turn the circuit off). I noticed that, unlike all the other supplies I have, the LED of this one takes a lot of time to turn off after I unplagged it, should I try to descharge it as u do with a capacitor?
no especially not, it’s normal , but try another power supply if it seems defective
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Hey @Dud, fortunately the circuit still works and the power supply doesn’t give problems atm! When I try just with the LDR, covering it with my finger, it works. Now I want to try the next step. In the image that u sent me labeled ‘without jack connection’, what is going to ground from the LFO?
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I knew that you would not use a jack to connect the second VCO to the CV in of the first, that’s why I made this drawing.
All ground must be connected together in a circuit, osc 1 and osc 2 ground together, if this is the case, connect the LFO to the resistor of the led
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Yeah I did that but nothing 
I have the feeling that the LED is not bright enough for the LDR to start working. The circuit is also getting quite messy and I’ m out of alligator clips eheh but I ordered more of them together with the other Breadboards, maybe it’ s good to wait a bit
to be sure, the output of the 2nd Osc (LFO), you use it only for the led and not also at the same time in audio output ? well just the sound of the 1st osc
Yeah I’ m using the audio out of the LFO and going into the CV in of the first VCO
yes but only for the led, not another wire to speaker in same time ?
so for more brightness : try a resistor of 500 ohm or little less for the led
Nono I’ m not sending audio to the mixer with the LFO, the signal goes only to the jack where the vactrol is
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Hi there guys,
i was wondering if there is posibility to a keyboard/ rezistor buton to the oscilator to control the pitch and to only play while the button is pressed?
Does anyone know if this is posible and have a schematic?
Thank you!
That’s what a VCA does! You’d have a CV from your keyboard going into the VCO to control the pitch, and a gate signal going into a VCA to control the amplitude.
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Thanks allot, do you know of a simple schematic for this? Also for my better understanding, i have to make a vca, before anything else, afterwards i need to make the vactrol cv in? Or is there another gate that can be done? Don’t have at the moment ldr, led on hand