Analog: Voltage Reference (publ. 2025-03-14)

The new breadboards haven't arrived yet, but I found an extra one, so I began putting together the voltage reference module. I am still following the Grappendorf schematics. Here is the photo of the circuit:

photo of voltage reference circuit

It outputs +1V to one of the terminal blocks and -1V to the other.

For some reason, following the resistance values listed in the schematic, I couldn't get the voltage down to +/- 1V, even if I turned the potentiometer all the way. So I replaced the 8.2k resistor with a 6.7k resistor and that got me in the correct range. I was able to trim to +/- 1.001 V. Here is the +1V output on the scope:

scope screenshot of +1V reference signal

There is a noticeable 60 Hz beat showing up there.

Another oddity is that the pins on the shunt diode appear to be different from the data sheet.

Copyright

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