Timer special

Introduction

For any electronics projects associated with timing, the sequence will require definitely a reliable timer to perform the function. Timer circuits give correct time passed or time elapsed will be given. A timer circuit can be used for any timing calculations. Timers are used in varieties of fields in our day-to-day life. Some of the popular usages are listed below

Photographic timer 

Kitchen timer

Athlete and sports timer

Treatment timer

Gym timer

Triggering timer

Ignition timer and so on.

Normally timer circuit operation is required from a few seconds to a few hours or even days. The timer should have the facility of setting it for the time period. Both on a timer and off-timers are in vogue. It all depends on the need of the project. 

The output of the timer varies according to one's usage. Visual and audible timers are very famous among hobbyists. Functional timers are quite useful especially for industries and other applications. Usually, a relay will be energized as the output which in turn performs the required job. 

Anyhow the timer circuit should be reliable and simple to use it. It should have the reset facility to set it right for the right function. A simple easy to build timer circuit are needed by everyone.  

There are lots of timer circuits available built around timer IC 555. But here I have explained a very simple circuit using just two transistors capable of functioning like the IC circuit. Besides that, it is very economical to construct as the parts can be procured at a low cost and the circuit is straightforward. 

The circuit

Working

C1, R1 and R2 are responsible for the timing of the circuit. The shown values give timing of approximately 3 seconds. That is the SPST relay gets energized after a lapse of 3 seconds and remains as it is till it is reset or power is disconnected. Hence normally to increase or decrease the timing of the circuit the values C1 will be changed with R1.

Parts List

Q!=BC547B NPN Transistor

Q2=BC557B PNP Transistor

D1,D2=1N4001 Diode

R1, R2= 470K ohm resistors

R3=22k ohm resistor

R4=39K ohm resistor

K1= SPST 9V Relay

PCB design full view

Component layout

Copper Track of the circuit

To sum up

The circuit can be easily assembled on the ready-made PCB design given here. Please give your valuable comments on the assembling of this circuit design.