Analog Electrics Lab 8

1) With the oscillator we’re studying the comparator outputs a square wave and the integrator outputs a triangle wave.

2) With an integrator, if Vin is positive the output voltage ramps down. If Vin is negative the output voltage ramps up.

3) With a comparator, if the op amp’s + input is connected to a greater voltage that that connected to it’s – input, the op amp’s output will be about positive 9v DC.  If the op amp’s + input is connected to a lower voltage that that connected to it’s – input, the op amp’s output will be about negative 9v DC.

4) There’s a formula for how fast the integrator ramps up or down:

change in volts per second at Vout = -Vin / RC

So the bigger the resistance R you use the faster the ramp gets, and the bigger the capacitor gets the faster the ramp gets.

5) The circuit at the end of this video is a monophonic synthesizer – it can only output one tone at a time. What do you think would have to do to make a polyphonic synthesizer that could play 2 notes at the same time? 3 notes? 4 notes? 100 notes?

In order to play multiple notes at the same time, I think you would have to make more inputs in the integrator with the same speed ramps.