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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Crystal test (CB9622E)
This circuit is one of many that the reader can find in this section for testing crystals. The...
Very low resistance static relay (CB8832E)
Found in a 1965’s Electronic Design, this circuit operates with a voltage of 1.5 V. The relay can...
Double tuning Pre-selector (CB9169E)
This circuit was found in a Popular Electronics from the 90's. The circuit has gained 10 to 20 dB...