This variable frequency circuit was found in a Popular Electronics from the 90s. The circuit outputs to a small speaker and can be powered by voltages as low as 3 V.
This simple electronic music box circuit was found in the April 1985 issue of Radio Electronics. The...
This circuit was found in an Electronics Now of the 80s applying to NiCad batteries of the time....
The power source shown for powering for small TTL circuits was found on a Radio Electronics...