PWM Flasher as Audio Circuit
The purpose of this experiment was to check out a circuit snippet that used PWM to fade a pair of LEDs in and out alternatively. LEDs can be set to various brightnesses with the use of PWM. The signal itself lets out a rather cool chirp or woof depending on how you set up the circuit.
The circuit is described here at http://members.shaw.ca/novotill/PwmLedChaser/index.htm.
Some additional circuits that use comparators are here as QLF (Quad LED Fader) circuits.
Basically, the first gate triggers the second one to oscillate from a 0 to a one state. The capacitor in the feedback loop of the second inverter will eventually charge and stabilize the circuit (at least thats my best opinion…to be honest, Im kinda guessing). When the cap is charged,its at a steady state.
The output is something like:
000000000010000011000011100011110011111011111111111111
and back the other way.
The frequency of the chirp can be modified with the resistor in second gates feedback loop. Unfortunately you cant get the signal too low. That can be solved though by counting down with a counter.
Applications could be to drive a vactrol or use as a signal source. I kinda like the idea of having three or more together as a soft switching sequencer.
In the meantime, here are some samples
Here is a simple sample of the circuit with the output driving the LEDs connected straight to my amp.
Here is a longer sample with some knob twisting and such