Saturday, June 20, 2020

Waveshaper current consumption and possible changes

The waveshaper op amps run fairly warm. Thus, I wanted to check the current consumption in case it was off the charts.

On the breadboard, the waveshaper current consumption is:

+15v: 26.5mA
-15v: 27mA
5v: 3.1mA (inc pulse VCA CV)

Of this, the waveshaper part (8 op amps) uses
+15v: 17.7mA
-15v: 18.1mA

Meaning the sub oscillator (10 op amps) uses
+15v: 8.8mA
-15v: 8.9mA

The JLCPCB circuit uses

+15v: 24.7mA
-15v: 24.2mA
5v: 0.5mA

In comparison, the Yusynth VCO (10 op amps + 1 comparator) uses

+15v: 27mA
-15v: 28mA

so I guess the current consumption is not that bad after all.

I am unsure what actually draws the power. I tried swapping 10k and 20k resistors for 100k and 200k around IC1B (pulse output) and the 27k DCO input resistors for 100k ones but that didn't change anything (or actually made it worse).

The sine wave amplitude is too low. Sine amplitude gain is done with a 15k negative feedback resistor and a 1.5k resistor from negative pole to gnd. Gain is 1+15k/1.5k = 11. By replacing the 1.5k resistor we can increase gain.


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