A Simple 30 Minutes Timer Circuit that works for long periods is really useful when you need a delay that lasts from a few minutes to several hours.
This particular timer circuit can turn off a device after about 30 minutes.
You can find it helpful in many situations like in automation systems, devices that need to switch on or off after a delay and for saving energy.
Using this kind of circuit can help save a lot of power.
The circuit is based on a special chip called the quad 2 input CMOS integrated circuit which is the 4011 model.
This setup uses a CMOS NAND gate 4011, a transistor, switch and a relay to make the long timing work.
You can power this circuit with either a 9V PP3 battery or a 12V DC power supply, which makes it easy to use in different situations.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistors (1/4W) | ||
| 10M | – | 1 |
| 4.7k | – | 1 |
| 1k | – | 1 |
| 10k | – | 1 |
| Capacitors | ||
| Electrolytic | 100µF 25V | 1 |
| Semiconductors | ||
| CMOS IC | 4011 | 1 |
| Transistor | BC547 | 1 |
| Diode | 1N4007 | 1 |
| LED | 5mm 20mA | 1 |
| Other Components | ||
| Relay | 12V | 1 |
| Push Buttons | – | 2 |
In the above circuit diagram when switch S1 is turned on capacitor C1 starts charging through resistor R1.
This charging causes the NAND gates to change their states.
Once the voltage on capacitor C1 reaches a certain level the NAND gates turn on transistor Q1 which powers the 12V relay
The relay stays on for a time that depends on the values of R1 and C1.
The main timing and switching are controlled by the CMOS IC 4011 which has four NAND gates.
The BC547 NPN transistor acts as a relay driver and the 12V relay is used to manage external devices.
The timing delay is mainly determined by capacitor C1 which is 220uF and the timing resistor R1 which is 10M.
A diode D1 specifically the 1N4007 is included in the circuit to protect against any reverse voltage.
The push button switch S2 is used to start the timer while switch S1 is for stopping it.
Formulas with Calculations:
To design your won circuit diagram following formulas must be used for Simple 30 Minutes Timer Circuit using CMOS IC 4011:
The timing duration (T) for this circuit can be estimated using:
T = 1.1 x R x C
where,
R = 10M (10 × 10⁶ Ω)
C = 100µF (100 × 10⁻⁶ F)
T = 1.1 × 10 × 10⁶ × 100 × 10⁻⁶ T = 1100 seconds = 30 minutes
By adjusting the values of R1 and C1 the time duration can be modified accordingly.
How to Build:
To build a Simple 30 Minutes Timer Circuit using CMOS IC 4011 follow the below mentioned steps for connections:
- Assemble all the components as mentioned in the above circuit diagram.
- Connect pin 1 of IC1 4011 to pin 2 of IC1 through one end of resistor R1 and other end to positive supply.
- Connect pin 3, pin 4, pin 10 and pin 11 of IC1 to base of transistor Q1 through resistor R4
- Connect pin 5 and pin 6 of IC1 through R2 resistor one end and other end between push buttons S1 and S2.
- Connect pin 8 and pin 9 of IC1.
- Connect pin 12 and pin 13 of IC1
- Connect pin 7 of IC1 to GND.
- Connect pin 14 of IC1 to 12V DC positive supply.
- Connect LED1 and resistor R3 in series between the collector of transistor Q1 and positive line.
- Connect the 12V relay coil between the collector of transistor Q1 and positive line.
- Connect the diode D1 across the relay coil as shown in the diagram.
- Configure the load and the load supply across the N1 and N2 of the 12V relay.
- Connect the emitter of transistor Q1 to GND.
- Connect a positive of capacitor C1 from pin 8 and pin 9 and negative of capacitor to GND
Conclusion:
This Simple 30 Minutes Timer Circuit using CMOS IC 4011 is a simple and effective way to create long delays for different projects.
You can change the delay time by adjusting the resistor and capacitor values.
The IC 4011 helps keep everything running smoothly and the relay makes it possible to control high power devices.