This percussion circuit was found in an Electronics World of 1968. The transistor may be general purpose and the power supplied at 12 V. The signal must be applied to an amplifier.
We found this circuit in an internet documentation. The circuit uses a 1 mA instrument, and the...
This circuit can be used to measure the frequency of a low frequency square signal. The signal can be...
This circuit is from 1985 documentation. The integrated circuit used is not very common today, but...