Hi there, I’m currently trying to make myself an AC non contact current detector. I already did a voltage detector that works well and would like to add a current detector as well.

I didn’t find anything on it except some sensors that you need to wrap around a wire to detect presence of current, but I want something with a probe I could detect just by getting near.

Something similar to this; http://www.extech.com/display/?id=14440

How can it detect 200mA to 1000A in a stick configuration?

 

Does your voltage detector tell you the amplitude of the voltage?

There is a difference between detection.....and measuring.

Which do you want to do?

 

It’s only for detecting, I made it using a decade counter so it flash/buzz 6 times/second when placed near a 60hz AC source.

What I want now is to make something similar but to detect current only, voltage or not.

I don’t need to measure it, I already have a multimeter and a clamp meter . (I am electrician btw).

I just want to build something pocket sized like my volt sticks, that could flash a led for voltage and a second led for current.

 

You are not going to beat 45 bucks. Buy your link.

 

The design doesn't suit my need, that's why I want to know how to do the detector myself, as I will be able to 3d print the ''perfect tool'' I'm looking for.

If I can't find a way to do it, i'll buy one to open it and see how I will be able to do mine.

 

How can it detect 200mA to 1000A in a stick configuration?

My guess would be it uses a sensitive Hall-effect chip.

 

If you want the satisfaction of building......it will require study and research.

You will need electronic prototyping equipment(many components and relative tools) and instrumentation.

Buy that unit and disassemble.......inspect closely......could you assemble those components?

You will not be able to 3D print the circuit.

 

A small coil at the end of the probe may work. You would probably have to screen it against electrostatic fields. You would have to design the screen so it did not form a shorted turn. It might also work with with a laminated or ferrite core to couple the core to the alternating magnetic field produced by the cable. A Hall effect sensor may also work to detect the altenating magnetic field. Probably neither of these methods would work with armoured cable as the armour wires are normally steel.

Les.

 

My guess would be it uses a sensitive Hall-effect chip.

I might try it.

If you want the satisfaction of building......it will require study and research.

You will need electronic prototyping equipment(many components and relative tools) and instrumentation.

Buy that unit and disassemble.......inspect closely......could you assemble those components?

You will not be able to 3D print the circuit.

I have access to instrumentations and material, and the 3D printing is for receiving the pcb, it’s the only part I can’t do myself. I use PCBweb so I will have to find a place to print it for me.

A small coil at the end of the probe may work. You would probably have to screen it against electrostatic fields. You would have to design the screen so it did not form a shorted turn. It might also work with with a laminated or ferrite core to couple the core to the alternating magnetic field produced by the cable. A Hall effect sensor may also work to detect the altenating magnetic field. Probably neither of these methods would work with armoured cable as the armour wires are normally steel.

Les.

The coil is the first idea I had, the Hall effect sensors seems to be a good option tough.

As for the armoured cable, it’s not necessary as you don’t make a direct contact with the wires. Even the volt stick is useless.

 

As long as you are dealing with separated conductors it should not be too difficult. Remember that the magnetic field "wraps around" the conductor, so if you want to sense it with a tiny solenoid-wound coil, the axis of the coil needs to be more or less at a right angle to the axis of the conductor.

Detecting current where the "out" & "return" conductors are close together, as in most residential & industrial distribution wiring, is harder because equal and opposite currents in the conductors cancel most of the magnetic field - most of which exists between the conductors instead of uniformly all around each one. It should still be possible, but is likely to require a more sensitive circuit and closer proximity to one conductor than the other.

A magnetic tape head might work as a pickup.

 

I'd lean towards hall effect as well.

I'd also second everything said below:

Detecting current where the "out" & "return" conductors are close together, as in most residential & industrial distribution wiring, is harder because equal and opposite currents in the conductors cancel most of the magnetic field - most of which exists between the conductors instead of uniformly all around each one. It should still be possible, but is likely to require a more sensitive circuit and closer proximity to one conductor than the other.