We found this circuit in an Australian publication from 1991. It is a kit of the time with input for a guitar pickup. The range is a few tens of meters.
This circuit is from a 1980 publication. In it we have a half-wave power control in which the SCR...
We found this circuit in the 1994 Linear Applications Handbook from National Semiconductor. The...
This sound intensity meter was found in a 90s Elektor. The circuit uses an integrated device from...