Blown Fuse Alarm (CB6109E)

We found this circuit in a 1967 Electronic design. However, it can be easily implemented even today as it uses only common diodes.

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Percussion Circuit (CB20308E)
This circuit produces the sound of percussion such as blocks, drum, bell, etc. The frequency...
Intense Signal Oscillator (CB19366E)
We found this oscillator in a publication from the 1960s. The frequency is around 600 Hz with the...
Audio Frequency Meter (CB20477E)
Found in a Popular Electronics from 1992, this circuit uses a PLL567 in an audio meter bridge that...