I want to be able to make my own custom valued current sense resistors 
in lowish volumes - 1's to perhaps 100's.
Requirements are

- 0.02 ohm to 1 ohm range
- Temperature stable
- Up to 1 Watt dissipation - usually far less.
- Non inductive within reason.
- Reasonably compact.
- Easy and cheap to manufacture.

If nichrome wire was easily soldered then winding nichrome or other 
resistance wire on a high value resistor is an obvious solution. 
Nichrome and similar is cheap and readily available and has near-zero 
temperature coefficient of resistance.

However, resistance wire types that I am aware of tend to dislike or 
hate being soldered. Other termination means are usually necessary 
including welding, spot welding, brazing or crimping. I'll consider 
all such ideas but thought that someone may have a bright idea on how 
to achieve this. Crimp contacts seem the next easiest solution but 
this is not a 'nice' solution.

I do not want to employ existing commercial resistors, at least at 
this stage as

- Values are custom and may need to be adjusted during prototyping.

- Suitable wattage, temperature invariant sub 1 ohm resistors tend to 
be specialist and expensive compared to other costs in this 
application.

- Temperature invariant resistors are relatively rare.

- I can control inductance etc as required.


These are to be current sense resistors handling currents of up to 5 
amps. Resistor value will vary with current.


Thoughts ?


        Russell

 

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