converting current signal to voltage

As you have a current source and you wish to drive a solenoid, which is basically a current operated device, working on the number of ampere turns etc...

Why bother with resistors? Just rewind the solenoid coil to run at the current available 200 mA to 700 mA

John.

i dont want to drive a solenoid, im using an output meant to drive one but i want to use it to drive an IC, hence why i need to change it to a voltage signal thanks - scott

Vague questions are hard to answer because we have no idea what your end goal is but...

The sense resistor is the easiest way to convert current to voltage, as said before the current will be coming from some power source and that voltage times the current is the power that will be dissipated somewhere. If you use a smaller resistor then you will dissipate more power in the current source but less in the resistor. If that is acceptable you can use a very small sense resistor and gain the current signal back up with a simple op-amp circuit. If you use the larger sense resistor then you will dissipate less power in the current source but more in the resistor and you are back to square one; a hot resistor that needs heat sinking may end up your best choice. Other options are Hall device for DC current, We have assumed DC current based on the initial question but if that is wrong and you are switching the current rapidly or it is AC then current transformer may do the trick.

Basically if the controller insists on driving that current (because it reports an error otherwise) then you must run that current and it will generate that much heat...so you'll have to get rid of it.

I'd suggest seeing how high a resistance you can get away with while still fooling the controller. It doesn't matter what you use, solenoid, resistor, transistor as a load it will still have to dissipate the heat.

So in sumary... use the highest total value of resistors which will still work reliably (one of which will be your 3.3ohm sensing resistor) and mount 'em on long legs or a heat sink..

It's simple and effective... go with it.

(Check the controller manual too, the output may be adjustable... if all else fails, read the instructions)

Have fun

Del

You might want to go talk to some of the Electrical Terninal distributors, like Phoenix Contact, Weidmeuller, Carlo Gavattzi. These guys make and sell devices to do elactly what you are looking for. They are not that cheap, but if you want it to work reliably in an industrial environment they might be worth the cost.

Change over to a VLSI Chip:

I guess you are working in dc, have you looked at a hall effect pick up?

We use one on an output sensor unit in a portable generator (which has dc & ac outputs) We have a 0-5V output and sum this with a circuit for the ac output [ct based to give 0-5V] to show the total load on the gen.set