This amplifier uses a 1975 integrated circuit, which is uncommon today. The circuit has a gain of 30 dB and uses a transformer-less output with 9 V power.
This polarity test or indicator indicates the polarity of a power line by LEDs. The circuit is...
This is the circuit of a digital clock published in the January 1975 issue of Radio Electronics magazine....
Found in an Elektor from the 90s, this circuit can be powered directly by the power grid. The...