Relay OFF Time delay timer by using NPN Transistor and Capacitor

Relay OFF Time delay timer by using NPN Transistor and Capacitor







OFF time delay timer by using NPN transistor and Capacitor, first of (B)base touch to positivevoltage so the capacitor also gets charged fully, remove to wire through the power to the base gets disconnected, the transistor continues to conduct with the aid of the stored energy in the capacitor which now starts discharging its stored charge via the transistor.The Relay also stays switched ON until the capacitor gets fully discharged.
  The value of the capacitor determines the time delay or for how long the transistor stays in the conducting mode.

 The component is using

1. NPN transistor(BC548)
2. 12v DC SPDT Relay
3. 1K ohm resistor
4. 1000uF/25v capacitor
5. 3v battery with LED


Comments

Unknown said…
How to decrease delay time to 10 seconds.
p.diavolikis said…
i made your circuit and it works fine but i have a question.
How can i do the same thing pushing the switch button on permantly and when i release it
to do nothing and only if i push it again to do the same thing?

thx
p.diavolikis said…
i dont care if i will use 555 or transistor
Unknown said…
Why a transistor is used in the circuit???

Unknown said…
Very interesting. I going to use this solution for construct one slingshot for my pinball project. Thanks.
Unknown said…
Is there a way to make this work with constant 12v and the switch signal to the ground?