DC-DC High voltage step-up - Page 1
Forum section: electronics / beginners

author: Foobrgoobs
author_rank: Newbie
timestamp: September 10, 2021, 08:38:09 am
content: Hi,I'm currently building a cloud chamber using Peltier coolers. Part of the cloud chamber is a high voltage mesh that sits above an earthed copper plate (probably somewhere around 10cm above it with plastic supports holding it up).I already have 13.3v from a pc power supply I'm using for the Peltier coolers so I was wondering what an easy and efficient way to step this up to about 1kV. This is just for the field so no current is needed and it doesn't need to be precise in anyway.I've found this converter on Banggood:https://uk.banggood.com/5V-12V-Step-Up-to-300V-1200V-DC-DC-Boost-Converter-High-Voltage-Power-Boost-Module-p-1179089.html?utm_source=googleshopping&utm_medium=cpc_organic&gmcCountry=GB&utm_content=minha&utm_campaign=minha-gbg-en-pc&currency=GBP&cur_warehouse=CN&createTmp=1I was basically wondering how this circuit works / what circuit people would recommend?Thanks

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 10, 2021, 09:06:12 am
content: high voltagebut what type? DC? AC?basically you take some old monitor you have the HV part inside, just apply some pulses to the transformer. i was joking course, that one needs to be more elaborated than this, but in principle what you found will give you the HV DC voltage (they multiply the V by oscillating the transistor that drives the 'smps' transformer, then the AC HVoltage is rectified)just verify the HV output may need to have the load always connected, but i guess it doesn't needif you need HV AC type, kill the rectifiers

author: Foobrgoobs
author_rank: Newbie
timestamp: September 10, 2021, 11:21:34 am
content: Sorry, I'll clarify.I need a DC - DC converter to convert 13v to around 1kV. It needs to be stable with no current draw (I will just be using it for the electric field so no current will be drawn from it). It also needs to be cheap.I don't know if a switch mode achieves this?Thanks

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 10, 2021, 01:12:56 pm
content: the one you mentioned seems fine

author: Jwillis
author_rank: Super Contributor
timestamp: September 10, 2021, 03:31:36 pm
content: The buck boost converter has an output current of 2 to 20mA nominal and 50mA Max . But you need to consider that energy is not created from nothing so it needs to come from somewhere . So the input current has to be proportional to the output current plus losses .

author: TimFox
author_rank: Super Contributor
timestamp: September 10, 2021, 05:25:41 pm
content: If the converter has a minimum current draw of 2 mA, then you need a suitable "bleeder" resistor < 500 k, which could be used as part of a voltmeter to monitor the output. Note the voltage and power requirement for this resistor: you might want to use several parts in series.

author: David Hess
author_rank: Super Contributor
timestamp: September 10, 2021, 07:29:53 pm
content: I would use a common switching boost converter but with a capacitor-diode voltage multiplier on the output.

author: CaptDon
author_rank: Super Contributor
timestamp: September 11, 2021, 12:23:01 pm
content: I don't know how resourceful your junk box may be. I have built a similar device. I useda 555 timer producing a pulse of about 10% on time 90% off time driving a buffer transistorand drove a small 120vac/12vac transformer in 'reverse' pulsing the low voltage side andgetting a sizable kick from the secondary of around 350 to 400 volts peak. It pulsed at around1Khz and my voltage multiplier was just run of the mill 1N4007 diodes and .01uf ceramicdisks. It ran from 12vdc and gave me the 1kv I needed for a 931 photomultiplier tube. Theenergy storage capacitor was .5uf@2kv and a bleeder resistor as well as the several dynoderesistors in series were chosen to limit the voltage to around 1kv. It was time intensive tobuild it, but it cost zero because every part came from my junkbox and I learned a few thingslike finding the 'sweet pulse repetition rate' where the transformer had the best kick voltage.