continuity tester

Dear all

Hope you are fine and doing well. I need your help. I am new to Arduino and I am trying to build continuity tester to measure resistance of 4 wires at the same time. I am using Arduino uno board. Can you please guide me through circuit and code. I'll be very grateful.

Thanks Abir

Let me get this straight, you are trying to build something but you have no clear description, no schematic, no plan of action and no code?

And please explain....

You need a "continuity tester" or an "Ohm Meter". Two different things that don't require the same approach.

You leave us to guess if you are trying to build a wiring harness tester or copper wire quality test.

sorry for the inconvenience, I am trying to build an ohmmeter which can measure 4 resistors simultaneously using Arduino uno. thanks.

I basically need a starting point, if you guys could please help me that would be great.

aabir786: I basically need a starting point, if you guys could please help me that would be great.

Tell us what you need to do - display method, how fast, how accurate . . .

You have mail

Starting point: Simple Ohm Meter

What you would do is replicate it to 3 additional Analog pins.

And buy 1% tolerance resistors to measure "against".

What do I mean?

Values and Tolerance

Thanks for the reply

Aim is to measure resistance in mili-ohms. An LED indication when resistance is >1 ohms would be sufficient. Incorporating a push button to start the code would be great.

Kind Regards

See... this is painful... you ask a super basic question... we start to help and then you finally say what you really want and it is more complicated than what you originally said. Meanwhile... we have to keep asking questions.

If you had said you needed to measure milli-ohms in the beginning, then I would not have now wasted my time with what I wrote in previous replies.

Accurately measuring resistances near 1 ohm is a much more complicated task. You need to have a reliable constant current source as a starting point. You won’t get that with what I provided as a starting point.

Milliohm meter with LM317 Constant Current Source

Thanks for your reply. I have looked at the link that yourself posted. Wondering if that circuit can be replicated to measure 4 resistors simultaneously?

Thanks

You have only one ADC on a Uno, so you can't measure more than one thing at a time. For consistency, it would make more sense to only build one circuit and switch it.

For consistency, it would make more sense to only build one circuit and switch it.

Isn't that what the A0-A5 interfaces already do?

I mean, I do agree with you mostly... since "replicating" is no longer just adding more resistors... but adding additional constant current sources... making it more complicated than adding a switching solution.

If you only make one converter, you've only got to calibrate one circuit.

to go down switching route, what be the best option, relays etc?

relays? No.

Analog Switches or (de)multiplexors used as a selector.

Personally, I'd go with relays.

I’m just thinking out loud here but if you have three (+5v) single supply LT1215 op amp VOLTAGE SUBTRACTOR with the gain set to something that results in an output <5V and you measure the three resistors SIMULTANEOUSL (with the op amps) , but READ the op amp outputs SEQUENTIALLY, (each connected to a different analog input) and do the math to obtain the resistance (for each) , then do the math to obtain the RECIPROCAL of EACH, then ADD the three reciprocals together then take the reciprocal of the SUM , would that not be the resistance of the three resistors in parallel ?

FYI,
Your post title is incorrect. What you described is not calleda “continuity tester”. It is in fact an “ohmmeter”.

aabir786: Dear all

Hope you are fine and doing well. I need your help. I am new to Arduino and I am trying to build continuity tester to measure resistance of 4 wires at the same time. I am using Arduino uno board. Can you please guide me through circuit and code. I'll be very grateful.

A "continuity tester" created by the help of an Arduino board tyically will NOT measure the resistance between cable ends.

Typically you'd just test: - if there is continuity where it should be (i.e. continuity between the beginning and the end of the same wire within the cable) - if there is no short circuit where no short circuit should be (i.e. between different wires within the cable)

With an UNO (total pins=20) and programming "Testing Result shown on Serial", which will use Pin-0 and Pin-1 for Serial connection to the PC, you have left 18 pins for cable testing, which would be enough for a "9-wire cable tester".

So you could create a cable tester for cables which contain up to nine single wires for cabling using an UNO. And I think I already posted full code for such a thing in this forum a while ago.

if I had to check simply continuity of a simple wire than what i have to do

if i want to make a generic tester, like if there is some problem in pin x, then it must print that pin x or wire related to pin x should be checked. what should i do. i need a quick reply