This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it can be used equivalent. The circuit is powered by the amplifier with which it must operate.
This direct-coupling three-transistor amplifier source some watts to a loudspeker when powered...
Both the field effect transistor and the integrated circuit of this 1970s circuit are no longer very...
This circuit was found in a 1987 magazine. It measures the pulse rate produced by a cardiac...