TTL Siren (CB9080E)

This simple TTL siren was found in a 1980s Electronics Today International. The power supply is 5 V and the integrated circuit can be the 7400.

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Ice Warning on the Track (CB6046E)
We found this circuit in an 80's Radio Electronics. The circuit uses a PTC sensor and an LED...
Rhytmic Lamp AC and 12 V (CB422)
In this circuit a 12 V lamp or LED blinks with the music signal applied to the input. R depends on...
Humidity Monitor (CB24940E)
Using a period sensor, this circuit was found in the February 1986 issue of Radio Electronics...