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.

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

PSU Designer II
Servo motor Tester with PIC12F675
ATtiny12 fuse
DC-10Khz frequency-voltage converter
Turntable Rumble Filter
ecm mic preamplifier
Stable Filament Supply
12v to 120v voltage inverter circuit
radio circuit diagram
Timer circuit
High-Frequency Oscillators
LS7263 Application Circuit Example