Music box (CB8626E)

This circuit was found in a 90s Popular Electronics. It uses an LS3404 melody chip that has several recorded melodies and that is uncommon nowadays.

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Shield triggered by oscillator (CB8516E)
This interesting configuration of optical triggering using an oscillator was found in a 90s...
10 s to 10 m sequential timer (CB1519E )
This circuit was found in a 1977 Radio Shack documentation. The circuit is TTL, which must be...
Photoelectric Sensor with Opposite Cells 741 (CB14645E)
We found this circuit in a manual of optoelectronics from Texas Instruments. In it photodiodes or...