Poptronics recommends this circuit for use in the car when the headlights are left on. The circuit uses a sensitive relay with contact current according to the headlights.
Based on the Texas Instruments LM393 or LM136, this circuit is intended for monitoring batteries with...
This circuit was obtained from an Electronics World of 1968. The transistor may be general purpose and...
The basic siren configuration shown in figure 1 activates a piezoelectric transducer and can be...