Author Topic: UCurrent Gold  (Read 1493 times)

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Offline elmezie

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UCurrent Gold
« on: January 16, 2017, 06:02:45 am »
Hello,

Is it possible to fix a blown resistor on the Ucurrent Gold? I can no longer get accurate values on the 1mv/ua setting?
I applied too much current while in that switch position and think I blew the resistor?


Thanks in advance for any information.
 

Offline tautech

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Re: UCurrent Gold
« Reply #1 on: January 19, 2017, 05:37:26 pm »
Hello,

Is it possible to fix a blown resistor on the Ucurrent Gold? I can no longer get accurate values on the 1mv/ua setting?
I applied too much current while in that switch position and think I blew the resistor?


Thanks in advance for any information.
Welcome to the forum.

Try this link and links within for the schematic and other info:
https://www.eevblog.com/projects/ucurrent/
Avid Rabid Hobbyist
 

Offline LA7SJA

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Re: UCurrent Gold
« Reply #2 on: January 19, 2017, 11:51:04 pm »
Take your most accurate ohm meter an measure on the ucurrent input in the mv/uA setting, it should read 10 KOhm (R2) (But if r2 has burn due to high current >0.1W in 10K what was the voltage and what else was destroyed). I have two fast lo capacitance diodes back to back over the input to prevent burning out the shunt resistors when I f... up.

Johan-Fredrik
"If at first you don't succeed, skydiving is probably not for you"
 

Offline JDW

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Re: UCurrent Gold
« Reply #3 on: March 29, 2017, 09:02:46 am »
I have two fast lo capacitance diodes back to back over the input to prevent burning out the shunt resistors when I f... up.

Can you post a schematic of where your diodes are located and also link the datasheet for us?

By the way, if the addition of those 2 diodes prevents shunt burn-outs without adversely affecting precision of the uCurrent Gold, why were they not included in the original design?  For truly, it is mentioned that the circuit was not "fused" at all in order to obtain the best precision possible.

Thanks.
 


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