The Simple Time Delay LED Circuit using is a cool setup that uses a transistor to make an LED light up after a short wait.
This easy to build circuit includes a transistor, a capacitor and some resistors to create that delay before the LED turns on.
It is really useful for things like power indicators, warning lights or any project where timing is important.
Also, it can run on a 10V DC power supply which makes it a great option for lots of electronic projects.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistors | 1k, 68k 1/4 Watt | 1 each |
| Preset | 100k | 1 |
| Capacitor | Electrolytic 10µF 25V | 1 |
| Semiconductors | ||
| Transistor | BC547 | 1 |
| LED | 5mm, 20mA | 1 |
This circuit is made up of some important parts including a transistor Q1, a capacitor C1 and two resistors known as R1, R2 and a variable resistor VR1 a preset.
At first the capacitor starts to gather charge as it goes through resistor VR1.
When the voltage on the capacitor gets high enough, it turns on the transistor Q1 which then lights up the LED1.
The time it takes for the LED1 to turn on depends on the RC time constant, which is calculated by multiplying the resistance of VR1 by the capacitance of C1.
Formulas with Calculations:
Below mentioned are the formulas with calculations for Simple Time Delay LED Circuit using Transistor:
The time delay T before the LED turns on is given by:
T = 0.693 × VR1 × C1
Substituting values:
T = 0.693 × 100kΩ × 10µF
T = 0.693 × 100,000 × 10 × 10 − 6
T = 0.693 seconds(693ms)
If required delay time can be increased by using a higher resistance for VR1 or a larger capacitor value for C1.
How to Build:
To build a Simple Time Delay LED Circuit using Transistor following steps are required for connections:
- Gather all the components mentioned in the above circuit diagram
- Connect base of transistor Q1 to one end of resistor R2 and other end of resistor R2 connect to one end of VR1 preset and other end of preset VR1 connect to positive of 10V DC
- Connect the collector of transistor Q1 to one end of resistor R1 and other end of R1 connect to 10V DC
- Connect the emitter of transistor Q1 to anode of LED1 and cathode of LED1 connect to GND
- Connect the positive of capacitor C1 to the junctions of resistor R2 and preset VR1
Conclusion:
This Simple Time Delay LED Circuit using Transistor with a delay is a easy and useful option for situations where you need a little wait before it turns on.
You can easily change the delay time by tweaking the resistor and capacitor values.
It is simple to build and does not need many parts, which makes it perfect for fun projects and learning activities.