Code Sidetone Generator (CB26323E)

This code practice circuit was found in a 1990s issue of Radio Amaterur Today magazine. It produces an audio tone with the 555.

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5 V Lamp Dimmer (CB13464E)
We found this circuit in a 1977 CMOS integrated documentation. The circuit also works with 6 and...
Binary Test (CB17400E)
Photo diode sensor switch (CB8335E)
This circuit is from a 1966 NASA documentation. The circuit uses a photodiode as a sensor. The other...