Readymade Miniature High Output Voltage DC to DC Converters

P

Pauldesign

Senior Member
Dear PICAXERS,

I see Rev Education now have a direct PICAXE dealer in South Africa but a bit pricey though, but great!

http://www.hobbytronics.co.za/c/670/picaxe-microcontrollers

On a serious note, please, my below inquiry is not PICAXE related but i can't resist asking on the forum because of the vast knowledge and response time of forum members.

My apologies if this thread offends anyone and no hard feelings if it is deleted :)

My inquiry is: do anyone know / have used a ready made low-cost DC to DC (5 Vin or 12 Vin to 500 Vout) converter at 1mA minimum at < $100 USD per device? I'm researching avalanche breakdown in space which requires such voltage.

Just to proof i'm not lazying around, I've already come across the below links but a bit pricey than expected:

http://www.emcohighvoltage.com/dc-dc-converters.php
http://www.picoelectronics.com/dcdclow/pe66_67.htm
http://www.milelectronics.com/mil_electronics_products_MV-Series.htm
http://deutronic.com/high-voltage-converters/12v-input.htm
http://www.spellmanhv.com/en/Products/Modules/1-5W-15W.aspx

Please any heads-up will be much appreciated.

Regards

Paul
 
rq3

rq3

Senior Member
It's not what you're after, exactly, but a $1 miniature audio transformer (8 ohms to 1000 ohms) will output over 600 volts if the low impedance windings are driven with a 5 volt square wave. It's unregulated and crude, you'd have to add the rectifier, and you won't get 1 mA, but you can't get any cheaper. You could even drive the 8 ohm primary with current limited Picaxe output pins (just so that we're not off topic anymore). Food for thought?

Rip

PS: Be careful. 1 mA at 500 volts is getting into the "deadly zone".
 
Buzby

Buzby

Senior Member
rq3 said:
... a $1 miniature audio transformer (8 ohms to 1000 ohms) will output over 600 volts if the low impedance windings are driven ...PS: Be careful. 1 mA at 500 volts is getting into the "deadly zone".
Click to expand...
Be VERY careful !.

The 'reverse wired transformer' is something I tried in my youth, and very nearly killed myself !.

I was well aware that my setup was going to generate over 3,000 volts, but hadn't taken into account that the primary winding ( now working as a secondary ) was handling voltages twenty times it's insulation rating. I got a very serious jolt when the insulation broke down.

I strongly suggest you get a ready built module.

Cheers,

Buzby
 
I

inglewoodpete

Senior Member
You could try an old electronic (xenon) flash unit. They generate 400 or 500 volts but I'm not sure if they can maintain 1mA. You'd have to experiment.

Stay alive.:)
 
techElder

techElder

Well-known member
Emco High Voltage is a very well regarded company in the realm of ultrasonic pulser manufacturers. I've purchase some of those in the past for my own research into ultrasonic flaw detection.

You can build your own, but its a witch's teat treat to know what the output is when loaded. You really have to depend on the manufacturer's product specs, because there's really no way to keep from blowing up a good o-scope trying to measure pulse load.

Pricing follows value in this case.
 
S

SteveT

Senior Member
Voltage_Multiplier_diagram.PNG

I don't know much about them but how about a voltage multiplier? Don't know what sort of current you would get out of one though. I believe they can be used for 'Jacobs Ladder' displays perhaps even Tesla coils???
 
P

PeteShep

Member
Just sort of word association.
don't know if the outputs are suitable, in fact I'm sure some are not:-
-o- Disposable camera with flash.
-o- Fluorescent bulb camping light.
-o- google "build a NIXIE tube power supply" for kits & ccts.
-o- "Emergency Standby Light" article EPE Mag Page 177 (or PDF page 23) note o/p is DC.
-o- google "power_an_led_driver_using_off_the_shelf_components" its EDN. not directly useful but the feedback is interesting...
 
darb1972

darb1972

Senior Member
You could use a trippler from the old CRT TVs (I believe you can still buy new). They were fairly cheap to buy. In the really early TVs , you could buy them separately from the EHT transformer. As the name suggests, they will (roughly) triple your input. Very similar (if not the same) as the jacob's ladder schematic shown a few posts ago. Not sure about current, but from memory, they could handle much more than you stipulated. They are fully insulated which adds an element of safety.
 
A

AllyCat

Senior Member
Hi Paul,

Pauldesign said:
do anyone know / have used a ready made low-cost DC to DC (5 Vin or 12 Vin to 500 Vout) converter at 1mA minimum at < $100 USD per device? I'm researching avalanche breakdown in space which requires such voltage.
Click to expand...
How crucial are the references to "Readymade" and "Small" in your OP title? I'm not clear if this is only required to emulate "space" conditions, or to actually fly in space? Perhaps the "flash gun" suggestions above are nearest to your requirement, but I'm not sure that xenon tubes normally use as much as 500 volts dc.

IMHO this shouldn't be too difficult to build from a few simple components. Much as described above, two capacitors and two diodes can act as a peak-peak detector, so 500 volts dc can be derived from an ac signal of less than 200 volts rms. Therefore a small, low voltage output, mains transformer (either 50/60Hz or "high frequency", depending on the required size, weight, reliability, etc.) used "backwards" could do the job without exceeding any design ratings. Then drive the "low voltage" winding from an audio amplifier or custom switching circuit.

But you can't beat the laws of physics, so bear in mind that with any voltage step-up method, the impedance is increased by the square of the step-up ratio. So if an output impedance of 10 kohms at 500v is required, then a 5 volt drive circuit needs to have an output impedance of less than one ohm (including the transformer winding resistance itself). In practice the output impedance will be higher, depending on the conduction angle of the diodes, etc..

As far as a TV tripler is concerned, AFAIR they were nominally rated for 1.5mA output and use(d) capacitors of about 1nF. But that is for 15 kHz operation, and also a lot more (absolute) ripple voltage normally can be tolerated on a 25 kV supply compared with a 500 volt rail !

Cheers, Alan.
 
P

Pauldesign

Senior Member
Thank you all for all the feedback, suggestions and links!

@ Alan, 'Ready-made and small' and of course space qualified is the end goal (required device) but any realistic device / setup that can be used to motivate the research / validate the concept for now should be alright.

My appreciations once more :)
 
darb1972

darb1972

Senior Member
AllyCat said:
As far as a TV tripler is concerned, AFAIR they were nominally rated for 1.5mA output and use(d) capacitors of about 1nF. But that is for 15 kHz operation, and also a lot more (absolute) ripple voltage normally can be tolerated on a 25 kV supply compared with a 500 volt rail !

Cheers, Alan.
Click to expand...
Hi Alan. Yes, in hindsight, the tripler suggestion probably wasn't the best idea. Still, if one had to do it with discrete components the tripler idea might be adaptable in conjuntion with a step-up transformer. I was thinking along the lines of a temporary solution. A cheap, ready made SMPS would be no doubt the best bet.
 
You must log in or register to reply here.
Top