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Stable floating power supply

Chengjun Li

Oct 21, 2014
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Oct 21, 2014
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Hi,

I have a MEMS device which is simply a actuator connected to a displacement sensor. I apply a voltage to the actuator to make it move forward, the load sensor is connected to a conditioning circuit, from the output voltage of the conditioning circuit, I could tell the displacement. Now I met a problem. I use agilent 6613C power supply to provide voltage, but the power supply is grounded and the ground potential is not the same as the conditioning circuit ground. I think they interact with each other which lead to a strange output voltage value. Then I try to use a battery. The output voltage is as my expectation. But the battery is not a stable voltage source. The voltage is decreasing. I wonder can I have some floating power supply like battery but is more stable?

Ps: I find another old power supply in my lab. But I don't know whether this one has the ability as I need.
 

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KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
Joined
Nov 28, 2011
Messages
8,393
How about putting a regulator between your battery and your circuit?

You didn't tell us what voltage you're working with, but regulators are available in a range of voltages, and adjustable versions.

You may need to increase your battery voltage to provide headroom for the regulator.

Avoid the old 78xx regulators; they draw significant quiescent current which will run your battery down even if the isolated circuitry doesn't draw much. Modern regulators, which are generally LDO (low dropout) types, are available with low quiescent current (also called "ground current") figures.

You can also get isolated switching converters that will produce a fully floating supply voltage. These tend to be noisy though, so they may not be suitable for your application. They are also not well regulated, so a regulator will still be needed. But at least they won't go flat and need to be replaced periodically.

There may be other options as well. If you describe the project in more detail and provide some schematic diagrams, we may be able to suggest other options.
 
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