Found in an American publication from 1968, this circuit generates pulses at a rate of 2,500 per second. The transistor can be replaced by a modern equivalent.
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...