How to set an exact voltage at the load? - Page 1
Forum section: electronics / beginners

author: Deva
author_rank: Newbie
timestamp: December 11, 2018, 06:31:27 am
content: Hey guys,I would like to develop a source meter for photo voltaic application(+2V to -2V).Can any one suggest me a source circuit for my experiment.

author: Dave
author_rank: Super Contributor
timestamp: December 11, 2018, 03:00:06 pm
content: To answer your topic: Sense lines for voltage feedback. Pretty much all SMUs have them, as do many of the better power supplies.

author: David Hess
author_rank: Super Contributor
timestamp: December 11, 2018, 05:05:12 pm
content: Are you looking for a circuit for an entire source meter or just what is required to add remove sense to a regulator? The later is pretty easily done in a few different ways as shown below.If you want a +/-2 volt range, then you need something more like a class-B or class-AB output stage with remote sense.Note that with remote sense, you can place a current meter in series with the output and not affect the voltage at the remote sense point.

author: Deva
author_rank: Newbie
timestamp: December 12, 2018, 05:03:12 am
content: Hi David ,Thank you very much for the reply.Quote from: David Hess on December 11, 2018, 05:05:12 pmCan I use this remote sensing circuit for measuring current measurement (10uA to 1A) with series resistors 10K, 100R and 1R operated by relays?

author: David Hess
author_rank: Super Contributor
timestamp: December 12, 2018, 05:18:42 am
content: Quote from: Deva on December 12, 2018, 05:03:12 amSure that will work. The sense resistors could even be switched by power MOSFETs. The remote sense will remove the voltage drop from the sense resistors and any switch.But like I said, if you want an output which can go both positive and negative, a different output stage will be required than a simple voltage regulator. It will resemble an audio power amplifier output stage.If you want to measure currents that low, then some attention will need to be paid to make the remote sense circuit not draw too much current itself but that is not difficult. Remove sense bias currents from nanoamps to picoamps are easily feasible using operational amplifiers as buffers.

author: Deva
author_rank: Newbie
timestamp: December 12, 2018, 07:03:25 am
content: Hi david ,Thank you very much for the reply.Could you please tell me about this Rp resistor . Is it a series resistor to measure the current .Could you send me a circuit with MOSFET s to work in both positive and negative(+2V to -2V and -1.5A to 1.5A) .it will be a great help for me .I worked with MOSFET IRF9540 and IRLZ24 in the attached circuit .

author: David Hess
author_rank: Super Contributor
timestamp: December 12, 2018, 03:23:04 pm
content: What Rp resistor? In that schematic, the 0.1 ohm 1 watt resistor at the bottom in the ground return is the current sense resistor.For bipolar operation, a series connected pair of MOSFETs would be needed for each sense resistor so both positive and negative could be blocked. This is essentially the same configuration as a MOSFET AC solid state relay but you are probably directly driving the MOSFETs without a photo-voltaic source.https://electronics.stackexchange.com/questions/92725/can-you-drive-back-to-back-mosfets-aka-a-solid-state-relay-without-using-an-op

author: Deva
author_rank: Newbie
timestamp: December 13, 2018, 05:18:11 am
content: Quote from: David Hess on December 12, 2018, 03:23:04 pmHi DavidThank you very much for the replyI connected the Photo voltaic cell as in the below circuit .