Found in a 1970s documentation, this mini-organ toy circuit makes use of an integrated circuit from that time. This component is difficult to obtain today.
This circuit was obtained from an internet documentation. The LED is inverted in the original, and the...
This circuit uses a sensitive vibrator that can be made with a reed-switch to activate a relay from...
This circuit from the 90s has RIAA equalization with a gain of 35 dB at 1 kHz. The circuit has an...