It is an automatic power off circuit diagram. If you need to shut-off any electronic device after a set amount of time then this circuit can do that automatically; when you are even sleeping! For example this auto power off circuit can be used with garden/porch light, soldering iron/ glue gun or similar other devices to auto shut it off for saving electricity or save the device, or you can use it to suit your own needs.
Caution: It is an AC High Voltage Circuit, so do not touch any part off the circuit or parts when connected to Supply Voltage. As you know it is dangerous.
 |
| Auto Power Off Circuit Diagram |
Theory of operation of this automatic power off circuit
- Here IC 555 is used as Monostable Multivibrator. It is a popular and very widely used timer IC.
- Input power for this timer circuit is provided using a transformer-less power supply which is made with a diode as a half wave rectifier, a voltage drop resistor, a filter capacitor and a zener diode.
- In power supply section, diode D1 is used as a half wave rectifier
- And R1 used as a voltage drop resistor and C1 used as filter capacitor
- S1, a push button switch is used to trigger the timer IC
- And the 555 timer output goes through a resistor (R4) to the ‘Gate’ of the TRIAC BT136
- When timer output is high it triggers the TRIAC and turn on the load/output device
- When C2 (time delay capacitor) charge up to 2/3 of input voltage; then 555 output goes low (Pin-3 is the output pin of 555)
- As timer output goes low, the TRIAC turn off the load/output device
- Here set time is around 20 minutes
- Set time can be adjusted by changing the C2 value
- A low leakage capacitor is recommended as C2
Parts List:
| Parts | Name | Value |
C1
|
Capacitor (Polarized)
|
220µF,12v
|
C2
|
Capacitor (Polarized)
|
1000µF,12v
|
C3
|
Capacitor (Non Polarized)
|
0.01µF
|
D1
|
Diode General
|
IN4007
|
D2
|
Zener Diode
|
8.2v,1w
|
R1
|
RESISTOR
|
10k,5w
|
R2
|
RESISTOR
|
1M, 0.5w
|
R3
|
RESISTOR
|
10k,0.5w
|
R4
|
RESISTOR
|
470Ω
|
S1
|
Normally Open
|
Push Button Switch
|
S2
|
FUSE
|
1A
|
T1
|
Triac
|
BT136
|
U1
|
IC
|
555
|
555 Pinout
Caution: It is an AC High Voltage Circuit, so do not touch any part off the circuit or parts when connected to Supply Voltage. As you know it is dangerous.
it is verygood
ReplyDelete