This toy transistorized organ was found in the May 1970 issue of Radio Electronics magazine. The trimpots are adjusted to the musical notes according to the key.
In the figure we have a simple way to obtain (almost) sinusoidal signals from an integrated...
This circuit, from a 1973 publication, locks the relay when the light that falls on the LDR is cut...
This transistorized receiver was manufactured in the 1960s and distributed worldwide. The diagram is...