Best continuity tester

Best continuity tester 

Introduction

A simple and at the same time very much utility-oriented best continuity tester circuit is described here for assembling and put to use. There are many circuits available on continuity tester for assembling. But this circuit is unique because it is very simple and used just two silicon transistors that are easily available from one's own shelf for assembling and use readily. It is also easily available and can be procured from any electronics shop in your own town.

For any electronics technician, a simple continuity checker is handy for day-to-day service work. The technical service becomes easier and much simpler and quicker if one uses this simple tester to check most of the electronics items such as electronics components or elements to put in the circuit for assembling work. 

Items to be checked

Wherever continuity check should be adopted for confirmation of proper working of the circuit elements, this tester becomes handy to test and get the immediate result 

Circuit elements such as

Fuses

Coils

Transformer windings -Primary and secondary

Relay coils

Low-value resistors

Continuity of the PCB copper track or its shorts in the pattern

With the ingenuity of the user, the tester can be used to test semiconductors like diodes, Transistors and LEDs for their primary status.

Generally, the continuity of any two points can be ascertained with the help of this tester.

The Circuit

Circuit schematic of the best continuity tester

Parts List

Q1,Q2 = BC147B NPN silicon transistors

LED1 = Red Light Emitting Diode (LED)

R1 = 22K ohm resistor

R2 = 15K ohm resistor

R3 = 680  ohm resistor

P1 = 10K ohm Potentiometer

SW1 = on/off switch

B1 = 3V Battery

Working

Connect the circuit elements/components under test between the two points A and B. Switch the circuit. LED glows when the continuity is OK. It may be necessary to slightly adjust the Potentiometer/preset to get the glow of the LED. Dry cells can be used as a power source since the current consumption is low. As such the whole assembly of the circuit is compact and small to carry for the service work.

Assembling

In order to assemble the circuit for utility purposes, a ready-made PCB has been designed and given here. One can easily assemble the circuit on the given PCB without any difficulty. 

PCB full view

Component layout

Copper track

Conclusion

Definitely, this mini continuity tester is an indispensable test instrument for an electronics service technician. Nowadays this becomes students' favorite project. Please give your comments and suggestions for the improvement of the gadget.