555 IC Delay Timer Schematic Circuit Diagram With Relay

Delay Timer Circuit Diagram Using 555 IC With Relay

You can easily make an excellent performance delay timer circuit using 555 IC and a relay. That is why a schematic circuit diagram of a delay timer with all kinds of technical support is published here. 555 ICs made by different manufacturers have different numbers, which are substitutes for each other, Such as NE555P, LM555CN, NE555N, LMC555CM (SMD), ICM7555, KIA555P, etc.

555 IC Datasheet, Pinout, and Pins Function

PIN	FUNCTION
1	GROUND
2	TRIGGER
3	OUTPUT
4	RESET
5	C VOLTAGE
6	THRESHOLD
7	DISCHARGE
8	VCC

555 Timer IC Functional Block Diagram

To understand how an adjustable delay timer relay module circuit works, you can carefully observe the functional block diagram and pin function descriptions of the 555 IC published below.

555 IC Block Diagram

Pins Function of 555 Timer IC

To understand how the 555 IC delay timer circuit works, pin assignment of the IC:

• Pin1 is the ground pin that connects to the negative (zero volts) power source.
• Pin2 is the Trigger pin. This pin enables the timing cycles for the circuit to operate. This pin is left free in the 555 IC delay timer circuit diagram because triggering is not required in this delay timer circuit.

• Pin3 is the Output pin. With a maximum current flow of 200mA, such a device can be loaded on this pin because the 555 timer IC can output a maximum current of two hundred milliamps.

• Pin4 is the Reset Pin. If the 555 IC needs to be reset in a particular circuit, connecting this reset pin to the ground will reset the IC's operation. This pin should be connected to the positive supply in a circuit that does not require resetting.

• Pin5 is the Control Voltage pin. This Control Voltage pin is connected to the inverting terminal of the internal comparator of the 555 IC; if an extra high or low voltage is required there, this threshold pin has to be supplied at that specified voltage.
• Pin6 is the Threshold pin. This threshold pin is connected to the non-inverting terminal of the internal comparator of the 555 IC. The output voltage/data is controlled by making this threshold pin voltage high or low compared to the internal inverting pin voltage.

•Pin7 is the discharge pin. This pin is connected to the collector of IC's internal NPN transistor. When the base of this transistor is reverse biased, its collector goes to low/0 voltage to discharge the time determinant capacitor. This pin discharges a capacitor, and the timing of the 555 IC delay timer circuit depends on that discharge time.

•Pin8 is the VCC Pin. This pin needs a positive supply ranging from 3 volts to 15 volts. If the power source is not SMPS, a voltage regulator IC like 7805 or 7812 is better for making a 555 delay timer circuit.

Delay Timer Schematic Circuit Diagram Using 555 IC

555 IC time delay circuit diagram is published below.

555 IC Delay Timer Circuit Diagram

Component List of 555 IC Adjustable Delay Timer Circuit Diagram

IC- NE555 IC or Equavalent
RL1- Use a 12-volt relay for a 12-volt circuit and a 5-volt relay for a 5-volt circuit.
D1- 1N4007
Q1- BC336 or A950 or Equavalent Cilicon PNP  Transistor.
C1- 470µF
C2- 0.1µF
C3- 330µF
R1- 10KΩ
R2- 4.7KΩ
RV2- 500KΩ Potentiometer.

555 IC Monostable Timer Calculation Formula:

In the monostable timing formula of 555 IC, T is time, 1.1 is the RC constant, R is resistance, and C is capacitance. First, match the following formula with this information.

T = 1.1 x R x C

In this formula, R or resistance should be calculated using Ohm (Ω); if the resistance is 1KΩ, it will be 1000 Ohms. And C or Capacitance should be calculated in Farads (F), i.e., if the capacitance is 1µF, it will be 0.001F
Suppose you build a delay timer circuit for a refrigerator. In this case, the power supply to the refrigerator requires a 5-minute delay timer.
In this case, 5 minutes 300 Seconds.

So, time in seconds (T) 300 = Constant 1.1 x 580,000Ω (580KΩ) x 0.47 Farad (470µF)
T = 1.1 x 580000Ω x 0.47F
Or 1.1 x 580000Ω x 0.47F = 299.86 Seconds or 5 Minutes.

Therefore, for a 5-minute delay timer, the R2 resistor (R2+RV2) value in the above circuit diagram will be 580KΩ, and the C1 capacitor value will be 470µF.
According to this formula for a 555 timer IC circuit, you can make a delay timer circuit from a microsecond to a few hours.

555 IC What are astable and monostable circuits, and what are their differences?
A 555 IC delay timer is a monostable circuit that turns on for a specified time. Here is an example of a stable circuit of a 555 timer IC, which turns off and on continuously according to a specified time.