Which wire goes where?  Where do I connect the battery positive terminal?
Don' have a multi-meter to find out?
Build this simple ELECTRIC CONTINUITY TESTER and it will be a great help!

Step 1:

This project and instructions are basically for the ‘neophyte’ or beginner in the things electrical. If you have basic electrical knowledge then you may find these instructions a bit simplistic and pedantic.
Basic theory info:
Any electrical device (preferably using battery based power) can be used.

For example devices making a sound, such as bells, buzzers or radios, can be used.
Also any device that lights up can be used: for example – a flashlight or a key chain light.  I have used a regular flash light many times in my early days of electronic testing adventures.

The method for making an electrical continuity tester is quite simple.
  a)     Break the connection at the power source (the battery).
  b)     Connect probe wires at the break point.
  c)     Use these probe wires to test electrical continuity of any wire or circuitry.

For example, if you touch the two probe wires together, the light will light up if your test device is a flash light, or there will be sound if your test device is a bell, or buzzer or radio.

Similarly, when you touch the probes to wires or points in your circuit that you want to test then if there is continuity you will hear a sound or see a light as explained above.  If there is no electrical continuity then nothing will happen.

In this instructable a simple 1 AA cell battery powered flashlight purchased at a "Dollar" Store for about $1.25 will be modified to be used as an electrical continuity tester. 
If you do not have a multi-meter to measure whether there is current flowing on a certain electrical path then this simple tester will do the job.  For example, you need to know which wire is to be connected to the positive terminal of a battery and which wire connects to the negative or ground.  By connecting this tester to various points you will be able to determine the correct connections.
With a multi-meter you would determine the proper connection when the meter is set to read resistance and the readout shows zero ohms resistance.  This tells you that you have a direct path from point A to point B.  
With this simple falshlight tester the light will come on when point A to B is a direct path.

Step 1: For this project - purchase a simple inexpensive flashlight.

CAUTION: Do not use this device for testing continuity on ‘live’ AC voltage circuits or on ‘live’ high-voltage DC circuits.  Also do not use around high-voltage electrolytic capacitors in circuits, because even if the circuit is not live, the capacitors may still hold a big enough charge to ‘zap’ you and they could be damaged.

Great idea!
Thanks man.
nice idea, also useful for the flashlight that can be always used as it is!
Thank you mario <br>walt

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