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Tester Circuit

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rahul489

New Member
Hello,

I am working on a test circuit and any help regarding would be appreciated. Here are the details

If the current in the wire is <100mA - LED should not glow
If the current in the wire is >100mA but <600mA - LED should glow
If the current in the wire is >600mA - LED should blink( optional )

The input voltage to the wire would be 12V dc . The other end of the wire is connected to a controller. Depending upon the current drawn by the controller , measuring the current and making the LED glow would be an indicator for Pass/Fail for the controller.

I am unable to get started on this. Any suggestions pointing me in the right direction would be appreciated.

Thanks ..
 

MikeMl

Well-Known Member
Most Helpful Member
Google "Hall Effect Sensor"
 

rahul489

New Member
@ MikeMI

I donot have any magnetic field to make use of. 12V-wire - controller ( this is how the connection would be). The current in the wire can be found out by a multimeter. But not using the multi meter to verify the Pass/fail criterion is the purpose.

I was thinking in to make use of some opamp( is it possible??)
 

MikeMl

Well-Known Member
Most Helpful Member
Are you willing to cut the wire and insert a small resistance in series? If so, Google "Ammeter Shunt".
 

rahul489

New Member
@mike

I dont know if I am explaining this right. I have already measured the current in the wire going to the controller. For the good controllers its around 400-550mA and for the bad ones its <100mA

Intention is not to make use of a multimeter or ammeter to measure the current and decide if that is good / bad.

Intention is to design a circuit which glows the LED if the current is within the Pass criteria or not glow if it is in the fail criteria.

Thanks!!
 

MikeMl

Well-Known Member
Most Helpful Member
You mean that you want to put a circuit inside your controller that detects if its current consumption is within spec.?
 

Willbe

New Member
If the current in the wire is <100mA - LED should not glow
If the current in the wire is >100mA but <600mA - LED should glow
If the current in the wire is >600mA - LED should blink( optional )
Use a shunt to feed a voltage amplifier to feed a window comparator, feeding a 555 oscillator.
100 mA is below the window.
100 to 600 is in the window and lights the LED.
>600 puts the 555 into the LED circuit.

National Semiconductor has app notes on using their comparators.

This will work. . .
 
Last edited:

Hero999

Banned
You can make an oscillator using a comparator.

A quad LM339 comparator could be used to perform all three functions.
 

MR.ALBAHRANI

New Member
hello ...

I think the best way to make this project is to find an (( IC of logic gates ))
which possible to contol the lEDs to glow or not depending on the current value ...



for example : using (( not gate )) IC when the current 100 mA and above glow when it's above 600 mA down ... etc

I hope that I gave you the best and helped you ;)
 
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