I need a high current source for testing hall sensors

[danrogers]

Hi all, I'm looking for a compact (if possible) current source to test a few hall sensors with. Voltage is not an issue but I want to have at least 10A at my disposal.

Can anyone recommend anything? Someone I know suggested that you may be able to find an LED driver but I dont think they would supply that much current?

Thanks!

 

[Cancelor]

Amps

An old PC power supply or a few winds of heavy wire round an old transformer

 

[MikeMl]

Do you have an old Weller soldering gun? The AC current that flows through the copper tip loop is ~20A. You could connect a loop of #12AWG house wire in place of the soldering tip. Just place the Hall effect sensor near the wire, and pull the trigger.

 

[Diver300]

Do you have an old Weller soldering gun? The AC current that flows through the copper tip loop is ~20A. You could connect a loop of #12AWG house wire in place of the soldering tip. Just place the Hall effect sensor near the wire, and pull the trigger.

Excellent idea Mike.

However, I think that you are a tad low on the current those things produce. I have used one with a loop of 1.5 mm2 wire (about #15AWG) and used it to cut expanded polystyrene. That sort of wire can take 20 A all day and only get slightly warm when inside insulation. It takes a lot more than 20 A to get it to plastic melting temperatures in seconds.

The iron is rated at 100VA and the voltage with the normal bit is about 0.23 V when running (0.3 V open circuit). If it only produces 50 W when running, that's still over 200 A

 

[danrogers]

Hi all, thanks for your input!

I dont think we have any of those irons around, but the PC psu could be an option. How much current do they supply on average?

 

[ericgibbs]

Hi all, thanks for your input!

I dont think we have any of those irons around, but the PC psu could be an option. How much current do they supply on average?

hi,
This may help/
How to Convert a Computer ATX Power Supply to a Lab Power Supply - wikiHow

 

[Reloadron]

Hi all, thanks for your input!

I dont think we have any of those irons around, but the PC psu could be an option. How much current do they supply on average?

Units like this allow for several 12 volt rails with current in excess of 20 amps. If you go this sort of PSU route I would look around for a good brand name unit with a single 12 volt rail.

Units like this can easily be run on the bench sans a computer. The setup is simple.

You could take a PSU like this and place a few variable loads on it and measure the current using a standard, precision calibrated shunt. That would afford you adjustable current (vary the load) through a known shunt for comparison to the hall effect sensors. Just build a small load bank and that should do it.

If you need help setting the PSU up to run on the bench just ask. I would use current from the 12 volt rail(s) but also hang amybe about a 10 Ohm 10 Watt resistor on the 3.3 volt rail just so the PSU always ahs a load on it. Some will argue this is not required on today's newer ATX PSUs but what the hell? Nothing to lose by doing it.

<EDIT> Beaten by Eric! </EDIT> -

Ron

 

[danrogers]

Hi Eric, thanks that looks most interesting! What is the purpose of the 10ohm 10watt resistor between the black and red wires?

Cheers

 

[danrogers]

lol, Hi Reloadron. Thanks for that! I guess that kind of answers the question I have just asked regarding the 10ohm resistor. I think I might give it a go, I've got 1 or 2 psu's lying about

 

[gerty]

" What is the purpose of the 10ohm 10watt resistor between the black and red "
The way I understand it is to load the 5 v regulator to keep it from oscillating, thereby stabilising the power supply.

 

[Reloadron]

" What is the purpose of the 10ohm 10watt resistor between the black and red "
The way I understand it is to load the 5 v regulator to keep it from oscillating, thereby stabilising the power supply.

Generally I suggest placing a 10 Ohm 10 Watt resistor across the 3.3 volt line to serve as a light load and allow regulation. The red wires are actually the 5 volt lines, orange is 3.3 volt lines and the yellow are 12 volt lines. That is true of most but not all PSUs as some systems like large workstations and servers use other color schemes. Rumor has it that the early switching PSUs needed a load to function so when used on the bench a load was placed across an output. I used the 3.3 volt (orange) lines but I guess it matters not. I also understood that these units regulated off the 3.3 volt line but don't know for sure.

Ron

 

[kinarfi]

Do you have an old Weller soldering gun? The AC current that flows through the copper tip loop is ~20A. You could connect a loop of #12AWG house wire in place of the soldering tip. Just place the Hall effect sensor near the wire, and pull the trigger.

I measured the current of my old weller soldering gun(100 watt I think) at 120 amps with # 12 wire using a clamp on ammeter. Instead of buying tips all the time, I just bend the solid wire into the shape I want and tin it as it gets hot the first time. Found out it works even better if you silflos the tip.

 

[carmusic]

There an easy way to do that just take an 1 amp load and make 10 turn of wire (small wire of course) into the hall sensor and your reading will show same as 10 amp current. This also work with Current transformer