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

lamp turning off prevention circuit of car
how to make automatic vehicle headlight
Rfrxd0420 Ask Receiver Reference Design
Analog circuit enforces slow servo response
BLY94 50W RF Amplifier Circuit
Enhanced 4 Digit Alarm Keypad
Alarm Control Electronic Keypad Project
RF amplifier coupling
0-360 phase shifter circuit diagram



Top