01-15-2009 02:49 AM
Hi,
We were thinking of using a PXI-5421 Arbitary Waveform Generator card to generate a 50Hz 'bright-up' signal but the max amplitude of the signal needs to be +/-14V but the max avaliable amplitude from the 5421 is +/-6V, any ideas?
Regards
Steve
Solved! Go to Solution.
01-15-2009 11:16 AM
The max amplitude is +/- 6V into a 50 ohm load (as the source impedance of the device is 50 ohms, to match the typical load). But if your load is high impedance, you'll get +/- 12 V out. Don't know if that is enough for you, but at least it's closer.
Neil
01-16-2009 01:58 AM
Thanks for the reply Neil,
Our load will be 27KOhms, is this high impedance?
Regards
Steve
01-16-2009 09:15 AM
Yes. You'll get (27,000 / (27,000 + 50)) = 99.815% of the voltage across your load, or +/- 11.978 V.
Neil
01-19-2009 08:31 AM
Neil
As it turns out +/-11V should be sufficient so the PXI-5421 should do the job
Thanks again
Steve
01-19-2009 09:25 AM
When you get the arb and are programming it, be sure to set the Load Impedance attribute to 27,000 ohms, so the driver knows the impedance of your load. If you don't set that attribute, it defaults to 50 ohms, and when you try to output 6 V, you would get 12 V on your load. But when you set the attribute, and tell us to output 11.5 volts (or whatever), that's exactly what your load will see.
Neil
Principal Engineer
Modular Instruments