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I understand protoboards have several limitations for prototyping circuits. However, most information found deals with parasitic capacitance such as to cause problems with higher frequency circuits.

My question is what are the limitations of breadboards in regards to high impedance circuits? I'm attempting to measure the voltage drop across a basic voltage divider circuit. Vout is across a fixed 10 Mohm resistor while the other resistance is a variable resistor of a sensor (500 kohm to ~1 Gohm).

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    \$\begingroup\$ Also important is how the circuit is cleaned post-assembly, and how it is protected from environmental contaminants. \$\endgroup\$
    – MarkU
    Jan 21, 2016 at 21:38

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If you are trying to measure the signal from a source impedance of 10meg ohms you will have to be very very concerned about the input impedance of the meter or measuring circuit. Unless the input impedance is at least 10 times higher than the source impedance the meter will completely load the signal and any readings of signal level will be totally invalid.

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  • \$\begingroup\$ Absolutely, a common input impedance of meters is 10 Mohms so if this were the case I would only be reading half of the actual voltage. I neglected to mention that I'm using a NI PXI-6251 to measure the voltage levels, which according to the datasheet has an input impedance of >10 Gohms \$\endgroup\$
    – rcola
    Jan 22, 2016 at 15:21
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I would imagine there will be a lot of luck involved. I would expect the palstic itself to be a very good insulator but I would worry (possiblly without good cause) about the sticky backing material that many breakboards have and about any contamination during handling and shipping.

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