Led Delay Timer | Electronic Project Circuits

Posts Tagged ‘led delay timer’

Courtesy Light by 7555 or TS555CN

15 seconds delayed switch-off, A good idea for bedroom lamps
This circuit is intended to let the user turn off a lamp by means of a switch placed far from bed, allowing him enough time to lie down before the lamp really switches off. Obviously, users will be able to find different applications for this circuit in order to suit their needs.

Parts :
R1 = 470R 1/2W
R2 = 100K
R3 = 1M5
R4 = 1K
C1 = 330nF-400V
C2 = 100µF-25V
C3 = 10nF-63V
C4 = 10µF-25V
C5 = 10nF-63V
D1 = 1N4007
D2 = 1N4007
D3 = BZX79C10
D4 = TIC206M
Q1 = BC557
IC1 = 7555 or TS555CN CMos Timer IC
SW1 = SPST Mains suited Switch

Circuit operation:
Due to the low current drawing, the circuit can be supplied from 230Vac mains without a transformer. Supply voltage is reduced to 10Vdc by means of C1 reactance, a two diode rectifier cell D1 & D2 and Zener diode D3. IC1 is a CMos 555 timer wired as a monostable, providing 15 seconds on-time set by R3 & C4. When SW1 is closed, IC1 output (pin 3) is permanently on, driving Triac D4 which in turn feeds the lamp. Opening SW1 operates the monostable and, after 15 seconds, pin 3 of IC1 goes low switching off the lamp.

Source: www.redcircuits.com

Be the first to comment - What do you think? Posted by admin - February 12, 2011 at 7:46 am

Categories: LED Flasher Tags: IC 7555, led delay timer

Timer set for 30 minutes by transistor

This circuit is based on learning of the discharge and charge of the C, which can be used as a timer circuit and can be applied in the off electrical appliances. The application has also put relay instead of LED can be enabled.
When you click the switch S1 will cause LED1 light told state ready to run S2 is a timer switch. On press switch S2 current will flow to the C1 charge fully. Then to discharge out through R2 to limit current flow to the bias for transistor Q1. Q1 and Q2, which work together to Darlington Compound. To have growth rates high to drive the LED2 light over time as C1 discharge all Q1 and Q2 stops LED2 is off if you want the timer circuit is longer. Then add the C1 and if you want a little time. to reduce it to C1.