When testing stuff like this - as well as TENS units, and the like - I always used my trusty 1 K as a load. That way the Ohms Law calculation(s) are simpler!
Otherwise, if you have time, you might want to check outputs at other loads:- 500 ohms (good skin contact) and 5 K (poor skin contact), for example.
I wouldn't worry too much about amplitude (apart from recording it "for interest"). Far more important are the series of output waveforms that this unit can produce (see the Operator's Manual
). See if you can reproduce the nice waveshapes given in the manual.
As long as you have a decent 'scope you should be OK.
is an old paper that you may find interesting. There used to be some proprietary testers for nerve stimulators - no doubt there are some nice ones about these days.
One last tip:- always use fresh batteries!
As an aside, you might want to think about how the user is to be reassured that the nerve stimulator works! In my experience this has often been the real
problem; you know, it works OK on your bench, but the anaesthetist et al
is not convinced. It is critical that the stimulator functions correctly, in order that paralyzing drugs are administered in the correct dose over time. But these relatively simple hand-held devices are subject to daily physical abuse, and often malfunction. However, it is sometimes not readily apparent that they are malfunctioning. A project for you (and any others) who want to Do Something Useful, perhaps - that is, a simple tester for the staff to use.Back in the Good Olde Days - when I used to come across many and various TENS units and nerve stimulators - for each type encountered I used to make a sketch of the testing set-up, record settings, and then make a sketch of the output waveform obtained on the 'scope; with a Filofax (anyone else remember them?) page for each example. Where possible (and for ease of comparison) I tried to use the same settings each time on the 'scope. I could then quickly decide if the next one tested was indeed a wrong 'un! I'm looking at the remnants now - it's amazing (well, perhaps not) how much those "square" (squareish) waveforms vary between manufacturers.