Two dc power supplies to get split voltage. - Page 1
Forum section: electronics / beginners

author: kashinath
author_rank: Newbie
timestamp: August 14, 2024, 07:09:08 am
content: I have korad KA3005D and a home made one based on the psu discussed herehttps://www.eevblog.com/forum/beginners/bangood-psu-enhancements/(mine has no overloaded components, i am using it without any issue). Now I want to connect these two to get +v -v voltage (for op amps circuits and audio amplifiers). How can it do it without blowing up ?

author: SuzyC
author_rank: Frequent Contributor
timestamp: August 14, 2024, 08:18:49 am
content: What exactly do you mean by "no overloaded components"?You can always prevent blowing things up by not subjecting your power supplies to stresses of current and voltage outside of their specs!If you can isolate the earth ground connection from the negative output connection of one of your power supplies than you can simply connect the two power supplies in series and use the point of connection of the two supplies as your ground reference for plus and minus outputs.

author: ganfetsic
author_rank: Newbie
timestamp: August 24, 2024, 05:43:44 pm
content: You need to connect diodes to the outputs of the psu'd that you will put in series.

author: IanB
author_rank: Super Contributor
timestamp: August 24, 2024, 05:52:11 pm
content: Quote from: ganfetsic on August 24, 2024, 05:43:44 pmWhy is that?

author: CaptDon
author_rank: Super Contributor
timestamp: August 24, 2024, 06:31:07 pm
content: You DON'T need to connect diodes in series with the supplies!!! What you may want to do is connect a diode ACROSS each supply in reverse direction (not conducting fashion) so that if one of the supplies is not up yet it can only see .6VDC of reversed voltage. If each of the supplies is not chassis / earth referenced on its output then as another poster mentioned you can hook them in series and use the center point as return for your +12 and -12 supplies. If by some chance both supplies have their negative side chassis / earth referenced then you can't simply hook them in series as the -12 supply will appear to be short circuited.

author: gnif
author_rank: Unknown
timestamp: August 24, 2024, 10:03:17 pm
content: ganfetsic was banned, this is farringdon again

author: schmitt trigger
author_rank: Super Contributor
timestamp: August 25, 2024, 01:46:10 am
content: Quote from: gnif on August 24, 2024, 10:03:17 pmTreez, Farringdon, Flyback or whatever his nom du jour is, seems to be attracted to this website like a moth to a shining candle, only to be burned again and again.

author: Konkedout
author_rank: Frequent Contributor
timestamp: August 25, 2024, 02:01:22 am
content: Regarding the diodes:The thread originator said that (he or she) wants to produce split supplies. Ifall loadsare connected between (+ or -) rails and the common ground there is not likely to be an issue.But if there is any chance of + being shorted or loaded to -, then one of those two may be forced into a reversed voltage at its output. That could destroy the power supply. POOOF!A way toreducethe chance of this is to connect an adequately rated diode antiparallel across each power supply output. You want to get low Vf diodes so I recommend schottky diodes which are reverse rated for maybe 120% to 160% of the power supply Vout. Schottky diode Vf goes up with its reverse voltage rating so don't use a 100V schottky to protect a 12V power supply.