This circuit reproduces the dial noise in a small speaker. The transistor can be a general-purpose type. We found it in an 80's Electronic Design.
In the figure we have the typical circuit of a stereo decoder using the TBA450N integrated...
This test for electrolytic capacitors was found in the October 1960 Radio Electronics magazine. Note...
The selected circuit is from the Texas Instruments optoelectronics manual. With it you can receive...