I haven’t did much lately expect reading and trying to get my AVR programmer working (without success) . And also this idea of a solid state tremolo/harmonic tremolo.
I ran out of 0 ohm jumper resistor and all those “breadboard wires” are terrible nightmare. However the circuit works fine.
This time I wanted to reduce the gain of the OTA , I just want a gentle unity or a gain voltage of 2 , not more. This requirement is to avoid noises and massive boost attacking the amp’s input. With unity , I could avoid a volume pot and keep the layout simple.
The 2nd wish is to have 0 signal at maximun intensity on the triangle waveform. As the output of the LFO is at Vcc/2 , I had to modify the bias point and making it lower , closer to 0V rail. That way the LFO oscillates at a lower midpoint, closing the gain stage when near 0V. This also reduces the max peak voltage and therefore the gain of the OTA.
The LM358s used for the all LFO section is quite interesting in this regard. The ouput can go as low as 0.80V before clipping.
As the harmonic tremolo need two LFO signals (each others 180° out of phaser) , the lower biased signal adds an issue. I need some more trimering. This still needs some more work , beside the breadboard adds terible noises as well .
Another idea would be to have a micro-controlled switching system allowing switching on the fly . But let’s keep it simple first !