Three-minute-timer


Posted on Oct 14, 2012

When Sl is off, Cl charges to within 0.5 V of the battery voltage through diode Dl and resistor R4. When Sl is closed, tbe anode of tbe PUT rises to the positive supply voltage. The PUT does not conduct, because battery voltage appears in series with tbe charge stored on Cl, which raises the gate of the PUT to a level positive with respect to the anode.


Three-minute-timer
Click here to download the full size of the above Circuit.

The timer relies on the discharge of capacitor Cl through resistors Rl, R2, R3,and R4. Once Cl is at zero volts, the PUT will turn on battery voltage to the Sonalert and cause it to sound.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Speaker-amplifier
Triangular Wave Generator Using Op-amp
16 step sequencer schematic
LED Bar Off Indicator
The Autonomous Drifter Circuit
PCB exposure box Based on ATmega8 AVR microcontroller
Open Source USB Generic HID devices based on the PIC18F and Windows
Two-phase stepper motor drive system circuit
Press light switch double circuit



Top