CMOS Siren (CB26157E)

Found in the 1991 Electronics Experimenter Handbook magazine, this circuit has good power and is recommended to be triggered by light.

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FM Tuning Indicator (CB10290E)
We found this circuit in an English magazine in 1975, but it can be easily assembled, as the...
Sinusoidal Oscillator 741 (CB8426E)
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PH meter (CB5324E)
This circuit is from an 80's documentation. The circuit makes use of a component of the era, the...