Long duration timer

  
The time circuit can provide a time delay of up to 20 minutes. The circuit is a standard relaxation oscillator with a FET current source in which resistor Rl is used to provide reverse bias on the gate-to-source of the JFET. This turns the JFET off and increases the charging time of Cl.
Long duration timer  - schematic

Cl should be a low leakage capacitor such as a mylar type.




Leave Comment

characters left:

New Circuits

.