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Electronics => Metrology => Topic started by: ScoobyDoo on December 05, 2021, 06:18:06 pm

Title: 10V 40mA DC Calibrator in Elektor Magazine
Post by: ScoobyDoo on December 05, 2021, 06:18:06 pm

https://www.elektormagazine.com/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001 (https://www.elektormagazine.com/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001)

https://youtu.be/i8ZxOXWNTnU (https://youtu.be/i8ZxOXWNTnU)

Title: Re: 10V 40mA DC Calibrator in Elektor Magazine
Post by: Kleinstein on December 05, 2021, 08:16:43 pm

I think there could be a potendial problem with the protection: The clamping at the output may be sufficient if the circuit is power powered, but with no power or a lower voltage (e.g. during turn off / turn on), the ouput votlage can exceed the supply of the chips.  One may still get away with this - depends on the chips.

Given the price for the 2 ppm/K resistors it is a rather strange way to generate the +-10.5 V. The simpler choice would have been 3 x 7 V ref in series and than just get the center right.  I guess 3 x LM399 would have been easier.

Title: Re: 10V 40mA DC Calibrator in Elektor Magazine
Post by: maxwell3e10 on December 06, 2021, 05:31:59 am

One can use LT5400 resistor matching network, its not expensive. That's what is done in SRS DC205, which has a very similar design.