Very basic question about SR830 lock-in

[Amplifierprobs]

Apologies if this is the wrong place to post this.

I'm currently attempting to run an experiment using a SR830 lock-in amplifier but don't know much about it or electrics in general as this area is very new to me.

I'm using the in built oscillator to drive a speaker which in turn oscillates a magnet/magnetic field inside a pick up coil. I am trying to use the lock into read the output voltage/current of the coil (and find the peak amplitude) by connecting both ends to the A/I input using a BNC. Is this possible/correct? Or am I misundersanding the lock in? How should I go about doing this?

I have attempted to get help from the manual without success, any help would be greatly appreciated.

 

[Gordianus]

1)Stanford Research has useful information in the website, download the user 's manual.

2)NEVER connect a speaker to the built- in oscillator (it hasn't been designed to drive such a load), you MUST use a buffer amplifier. Again, the user's manual will give you the limits of every input and output

 

[f95toli]

You probably need -as Gordanius has already pointed out- some sort of buffer amplifier to drive the speaker; the oscillator output of the SR830 is a voltage output and can't really drive difficult loads. That said, since you are using a lock-in you only need a tiny signal so you do not need lots of current; i.e .do NOT use a power amplifier since you could easily blow up the inputs of the SR830. Personally, I would use a separate function generator (something that can source a few tens of mA) both to drive the speaker and as a reference for the lock in (i.e. I would not use the built in oscillator at all).

Also, it almost sounds like you are using both inputs of the SR830 which is only needed if you are doing a differential measurement; you should be able to do this measurement single-ended (i.e. just using one input). Hence, you need a BNC cable from the DUT (the speaker in this case) to the input. Just keep an eye on the polarity (i,e, where your ground is).

 

[Amplifierprobs]

Thank you both for your replies, they've been very helpful
It turns out I had forgotten to strip the ends of the coil wires properly, it's always the simple things!
I was also able to source a separate function generator up to the task of driving the speaker and using your set up advice, my experiment is currently running as expected.
Thanks again for all your help!