The LED frequency flashes depends on the value of the capacitor tested according to the table. We found this circuit in a Popular Electronics from the 80s.
This fully isolated control circuit provides an output signal by triggering a 130 mA relay when...
The capacitor used in this circuit can have values between 5 and 30 uF. The circuit is of old...
We found this circuit in an old Argentine publication. The transistor can be replaced by a more...