I'm looking for a shunt to put in a circuit to measure 100mA up to 1.5A. I'm looking on RS components and the smallest shunt I can find is below. This will work quite fine but I think it is larger than I need at 6.4 x 3.2mm. It's also 1W and I calculate I need on 200mW. I was imagining something that looks like a regular resistor that is also around 50m ohm but can't find anything. Does anyone know of anything available?

 

200mW 0805 or 1206 should do the job.
see
http://www.farnell.com/datasheets/2710719.pdf

Picbuster

 

200mW 0805 or 1206 should do the job.
see
http://www.farnell.com/datasheets/2710719.pdf

Picbuster

Thanks, I will check it out

 

What are you planning to connect the shunt to? What dynamic range do you need?

Just planning to run some LEDs, around 9W

 

200mW 0805 or 1206 should do the job.
see
http://www.farnell.com/datasheets/2710719.pdf

Picbuster

I have ordered them and they have arrived. I haven't had the chance to try them out yet but will give them a go soon. They look appropriate for what I need, the smaller of the 2 is about the size I would expect for surface mount components. I'm glad I got a larger one now as the smaller one will be difficult to breadboard Thanks everyone for your help

 

No need to order anything and wait around a week for it to arrive ... what wire do you have in your scrap box ??? Any enameled copper wire?? Find the appropriate gauge , search how many meters to one Ohm , and cut the length you need ... this will give a very accurate resistor . Make it into a loose bundle .... the bigger the better to help keep it at room temperature . That's the only thing to be aware of , that it doesn't get too warm as this will slightly change the resistance ..... but @ 200mW this is very unlikely...........a shunt made this way should not change resistance 1% over your current range.

It's not even 200mW .......... 50mOhm @ 1.5A = 112.5mW

The reason such a shunt is not easily available is perhaps because people do make their own ... At high currents and powers it's a different story , for an Amp meter shunt you need something fairly compact , and it will get hot , so an alloy is needed that has fairly constant resistance/temp.