This circuit for effects on music synthesizers was found in the May 1983 issue of Radio Electronics magazine. The circuit requires a 15 V power supply.
We found this circuit in a technical documentation on the National Semiconductor LM3909. The...
The LEDs act as diodes, so if good they will show the same characteristic curve. Arrangment shown...
This circuit is from an old English publication from 1968. We can implement it with TIP32...