The capacitor used in this circuit can have values between 5 and 30 uF. The circuit is of old documentation for radio amateurs. Observe the special source used in the supply.
We found this circuit in an 80's Radio Electronics. The circuit uses a PTC sensor and an LED...
In this circuit a 12 V lamp or LED blinks with the music signal applied to the input. R depends on...
Using a period sensor, this circuit was found in the February 1986 issue of Radio Electronics...