Abstract:
This simple timer makes the output LED “on” for some time and then goes “off”. The chip NE555 (or equivalent) is off the shelf available and is low cost.
The circuit
Short description
- IC 555 is connected in monostable mode as shown in the diagram.
- You can set the timing by setting the potentiometer (100k) value.
- To start the timer, press and release the push button. (The button is “push to ON” type.
- When the timer starts, the output LED glows. It glows for the set amount of time and then is OFF.
- You can calibrate the potentiometer knob to set time properly.
- Maximum time for which the LED glows is approximately 16 seconds.
- Minimum time for LED glowing is approximately 1 sec.
Material list
| Sr. No. | Component | Specifications | Quantity | |
| 1 | IC NE555 | standard | 1 | |
| 2 | Resistors | 10k, 0.25W | 2 | |
| 3 | Resistors | 1k, 0.25W | 1 | |
| 4 | Potentiometer | 100k,16mm, plastic shaft | 1 | |
| 5 | Capacitor | 100mfd, 25V | 1 | |
| 6 | Capacitor | 0.1mfd, disc | 1 | |
| 7 | IC socket | 8 pin,DIL | 1 | |
| 8 | Battery | 9V, flat, non-rechargeable | 1 | |
| 9 | PCB | general purpose, 4″X4″ | 1 | |
| 10 | LED | red, 5mm | 1 | |
| 11 | Misc | wires, solder metal | ||
This project is available in the kit form. Contact Omkar to buy it. This site has no commercial connection with his activities.
