I am a biomedical engineering student that isn't entirely versed with electrical components and needs help selecting a power supply. So the end goal is to have a power supply that can provide an output in mV (variable from 1 mV to 10) that can also flip polarity with regularity (so a bipolar power supply). What do you all suggest?
Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations JAE on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Power Supply - Ultra low output in mV
- Thread starter mikez8
- Start date
Skogsgurra
Electrical
I suppose that you need an isolated supply with minimum leakage current and almost no load current?
Then, a simple one cell hearing aid battery with a voltage divider will work. You will lose power in the voltage divider, yes. But with miniscule power consumption - does it matter?
Polarity reversal. You can use a mid-point to get a plus and a minus potential. Then switch between plus and minus with a couple of low power FET which you control from an astable FF (old school).
If you need remote control- there's IoT to help.
If you want continuous operation over many months/years, you will need energy harvesting or a plain mains connection. Mains is simple, but then there's the leakage current problem. Two transformers with the low voltage secondary of the first supplying a second transformer and the mid-point of the first secondary connected to the specimen's bulk eliminates the leakage. You do not need a true midpoint tap, a potentiometer with slide grounded works well, sometimes better since you can null out leakage by adjusting the potentiometer.
Then, there must be lots of such products available commercially. No luck there?
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
Then, a simple one cell hearing aid battery with a voltage divider will work. You will lose power in the voltage divider, yes. But with miniscule power consumption - does it matter?
Polarity reversal. You can use a mid-point to get a plus and a minus potential. Then switch between plus and minus with a couple of low power FET which you control from an astable FF (old school).
If you need remote control- there's IoT to help.
If you want continuous operation over many months/years, you will need energy harvesting or a plain mains connection. Mains is simple, but then there's the leakage current problem. Two transformers with the low voltage secondary of the first supplying a second transformer and the mid-point of the first secondary connected to the specimen's bulk eliminates the leakage. You do not need a true midpoint tap, a potentiometer with slide grounded works well, sometimes better since you can null out leakage by adjusting the potentiometer.
Then, there must be lots of such products available commercially. No luck there?
Gunnar Englund
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
daveross100
Military
Simple : A voltage divider and a buffer that can supply the load current
any question: email daveross100 at gmail dat com
any question: email daveross100 at gmail dat com
To have some accuracy, a voltage reference IC should be used, followed by a voltage divider and op amp buffer as suggested by Daveross. Power it from a couple AA battery cells as suggested by Skogsgurra and you have a device that just by switching the electrodes out of it you switch polarity.
Sounds like you're doing some experiments in a biological wet lab.
Sounds like you're doing some experiments in a biological wet lab.
- Status
Similar threads
- Question
- Locked
- Question
- Locked
- Question
- Question