Follow-up - Mini 3-wire volt meter - input impedance?

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ottensmeyer
 
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Follow-up - Mini 3-wire volt meter - input impedance?

Post by ottensmeyer »

Hello -

I'm looking at using p/n 705 (mini 3-wire volt meter) to measure the sense resistor in a 1/1000 (10M total) divider from a 4kV supply and separate voltage supply for the meter. I saw posts:

viewtopic.php?p=827978
viewtopic.php?p=456163

Is there any way to get a note back to the original posters to inquire whether they found/measured their own answer to their question ("what's the input impedance?")

thanks!

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adafruit_support_mike
 
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Re: Follow-up - Mini 3-wire volt meter - input impedance?

Post by adafruit_support_mike »

I have a couple on order, and will characterize them when they arrive. Current ETA, given weather conditions, is Friday.

UPDATE: The voltage meters all draw 1mA for full-scale deflection, putting their impedances at:

0V-3V meter (pid 3989): impedance 3k, current 0mA to 1mA
0V-5V meter (pid 3990): impedance 5k, current 0mA to 1mA
+/-15V meter (pid 4403): impedance 30k, current -0.5mA to 0.5mA

I also tested the +/-1A ammeter (pid 4404) and found that its burden voltage is 90mV @ 1A, putting its impedance at 90mOhm.

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