This circuit produces the sound of a motorcycle or an outboard motor. The frequency is adjusted in the pot. For supplies above 9 V the BD136 must be equipped with a small heat sink.
This circuit is based on the Texas Instruments LMC662 and has the function of monitoring the audio...
Found in an Electronics Now from the 1980s, this circuit uses some components that are still...
This alarm, from a 1996 magazine, can be fitted with two BC548s in the original configuration...