High voltage bench power supply... o just need a schematic..or any help..pls. - Page 1
Forum section: electronics / projects

author: SK_Caterpilar_SK
author_rank: Regular Contributor
timestamp: May 30, 2018, 08:56:55 pm
content: So heres the thing. Im getting into vacuum tube stuff lately a bit too much and I want to have a variable linear high voltage power supply. Everything is a bit too expensive for my standards so I would like to build my own one. I was powering the tube stuff with my home made janky switching supply with no scientific calculations whatsoever. (I just made a TL494 flyback converter thats all..). Unfortunately this supply is not good enough and im still refining the schematic, but I also want a linear HV sbench power supply.The specs:50-800V output voltage (no need for a true 0 regulation)at least 500mA output currentthats all.Thanks for all help.

author: oldway
author_rank: Super Contributor
timestamp: May 30, 2018, 09:42:50 pm
content: Welcome on the forum.A lot of threads about it:https://www.eevblog.com/forum/beginners/high-voltage-bench-power-supply-design/msg1463577/#msg1463577https://www.eevblog.com/forum/projects/looking-for-yours-opinions!-hv-stabilized-power-supply/https://www.eevblog.com/forum/projects/30-400v-tube-power-supply-with-three-pl500/msg1009252/#msg1009252https://www.eevblog.com/forum/projects/ever-felt-the-need-for-a-0-350v-lab-power-supply/msg104520/#msg104520https://www.eevblog.com/forum/beginners/high-voltage-supply/msg1193469/#msg1193469https://www.eevblog.com/forum/projects/high-voltage-power-supply/msg1158551/#msg1158551https://www.eevblog.com/forum/repair/repairing-a-heathkit-ps-3-0-500vdc-tube-power-supply/msg601419/#msg601419https://www.eevblog.com/forum/projects/overhauling-high-voltage-vacuum-tube-(valve)-power-supply/msg388829/#msg388829https://www.eevblog.com/forum/beginners/high-voltage-bench-power-supply-design/

author: SK_Caterpilar_SK
author_rank: Regular Contributor
timestamp: May 30, 2018, 10:18:20 pm
content: Quote from: oldway on May 30, 2018, 09:42:50 pmThank you very much. I will look into thoose.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 02, 2018, 01:55:49 pm
content: I would start with a board like this:https://www.aliexpress.com/wholesale?SearchText=DC-AC+converter+220VSome of these boards are based on a TL494, others have a SG3525 and they are available in different power ranges.With a bit of tinkering the output voltage can be adjusted (opamp, high voltage voltage divider)They are made for "AC" out, but a bridge rectifier can easily remedy that.Add a voltage doubler or tripler if the output is not high enough.

author: oldway
author_rank: Super Contributor
timestamp: June 02, 2018, 03:41:53 pm
content: Quote from: Doctorandus_P on June 02, 2018, 01:55:49 pmNo need of a crap not protected Chinese inverter to obtain 220V or 380V ac....a simple transformer do the same thing....Add a variac if you want to adjust output voltage.And a circuit breaker in the output of the variac to make it short-circuit proof.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 03, 2018, 02:13:46 pm
content: Quote from: oldway link=topic=115003.msg1582483#msg1582483No need of a crap not protected Chinese inverter to obtain 220V or 380V ac.[/quote

author: oldway
author_rank: Super Contributor
timestamp: June 03, 2018, 05:40:52 pm
content: Yes, it is crap for different reasons:1) output voltage is not adjustable and can't be modified (µc controlled)2) Not protected against short-circuit3) no current limitation and not possible to implement it.4) need a high power 12V power supply5) need use of fast diodes if rectification needed.6) Inductive load not allowed7) as most of this low cost modules, it is probably made with bad quality/recycled components.8 ) the Heat sink is not furnished and is not even specified They don't say what is the thermal resistance needed for full output power.9) generating o lot of HF noises....Read the specifications of those modules....Quotehttps://fr.aliexpress.com/item/DC-AC-Converter-12V-to-220V-380V-18V-AC-500W-Inverter-Board-Pre-booster-module-free/32694494406.html?spm=a2g0w.10010108.1000016.1.4a9dd7d7d7mT2s&isOrigTitle=trueQuoteAnd on this forum, whe are getting tired from problems with this kind of cheapy modules....30V power supply that is an OP killer, vacuum tube preamplifier that does not work, .....

author: flowib
author_rank: Contributor
timestamp: June 06, 2018, 11:01:07 am
content: Your asking quite a lot here, 800V 500mA is 100W over the biggest HV supplies Philips made. (PE4832)http://www.jogis-roehrenbude.de/Roehren-Geschichtliches/Roehren-Netzteile/PE-4832.pdfAnyway i can tell you from experience that this amount of regulated stabilised power is overkill for what you need. you're better of building a 0-300V 0-100mA unit with adjustable current limit. adjustable current limit that can be set at 1mA is VERY useful for slowly charging electrolytic capacitors.Quite frankly if your into Push pull stages at that power level, the absolute value of the HT wont matter much, nor does the ripple because this is canceled in the OPT.At these power levels and voltages mosfets dont work as linear power regulators their DC SOA is significantly worse then the specs would suggest so the only viable method is either Linear mosfets or vacuum tubes.One of the cheapest high power tubes would be the GU-50 if i would have to take a guess.If you still want to go that way, if you manage to switch the B+ on the input to keep dissipation in check, you can build something like this with 4 GU50http://www.jogis-roehrenbude.de/Roehren-Geschichtliches/Roehren-Netzteile/Roe-Netzteile.htmCheers

author: 001
author_rank: Super Contributor
timestamp: June 11, 2018, 08:53:38 pm
content: DIY HV bench supply is pitfallI absolutely have no reasons to try it againAnd how are You?