benny_profane
Well-known member
My quadratron build has a slight issue with the LFOs when dual mode is activated. In single LFO mode, the entire range of knob is useful. In dual LFO mode, the upper third or so locks up the LED at full brightness with no oscillation. Note that at least one other builder has had this issue.
The build has the suggested LEDs (Tayda diffused green). The span pots have been increased to B2K from the original B1K. I've tried tacking a 2k resistor in parallel with the pots to simulate the stock value, although I don't think that this is related to this problem. The problem is exhibited when the pot is completely turned up and there is no resistance between the output of the op amp and the series resistor / LED array.
I've tried swapping the IC6 with another TL022 with no change in behavior.
I pulled one of the LEDs for testing. I'm getting consistent Fv measurements with two different meters for that LED and samples from two different batches of green diffuse LEDs from Tayda.
I'm stuck (much like the LEDs).
BUILD DOCUMENT
The build has the suggested LEDs (Tayda diffused green). The span pots have been increased to B2K from the original B1K. I've tried tacking a 2k resistor in parallel with the pots to simulate the stock value, although I don't think that this is related to this problem. The problem is exhibited when the pot is completely turned up and there is no resistance between the output of the op amp and the series resistor / LED array.
I've tried swapping the IC6 with another TL022 with no change in behavior.
I pulled one of the LEDs for testing. I'm getting consistent Fv measurements with two different meters for that LED and samples from two different batches of green diffuse LEDs from Tayda.
I'm stuck (much like the LEDs).
BUILD DOCUMENT
