High Voltage Power Supply 2

[boreholelogger]

Hi, I am trying to design a High Voltage power supply circuit that can produce 1250V @ 0.1mA. This supply has to run off a 9V battery and thus current consumption is a big problem. I was wondering if anyone had any idea of how to go about it?.

Thanks, boreholelogger

 

[IRstuff]

see:

http://www.picoelectronics.com/dcdclow/avhigh.htm

TTFN

 

[boreholelogger]

IRstuff, Thanks for the message and the link but they all draw too much current (33mA) at the input for a 9V battery. The way I understand batteries, is that 9V rated at 500mAH, means that the battery will deliver approximately 8.5V to 9V for 20hours. This means that the 9V battery at the very most, can supply 25mA/hour for 20 hours. This is why the job is so difficult.

 

[IRstuff]

You didn't say anything about how long it had to work, and still haven't

TTFN

 

[IRstuff]

I think you need to revisit your requirements. 1250V at 0.1 mA is 125 mW. Even assuming 100% efficiency, the load current draw would be 14 mA.

Your closest off-the-shelf supply appears to be those specifically for photomultiplier tubes. EMCO and GLHITEK have some with low unloaded input power.

TTFN

 

[boreholelogger]

Running time is at the least 2 hours.

Yeah so I'm going to be running on maximum current anyway by the time I include losses. I have designed a cockroft-walton voltage multiplier circuit with a HV transformer and it seems to do the job but won't run off a 9V battery for very long, not consistently anyway.

Thanks IRstuff

 

[OperaHouse]

Is this just one? I would use a switching regulator like TL494 or SG3524 and drive whatever junk box ferrite transformer I had from an old switching power supply and diode multiply up to the voltage I needed. Internal transistor drivers of the switcher should be sufficient. I'd think you could do that in under 45ma.

 

[VEBill]

There are piezo-electric 'transformers' that might (?) be applicable (but I'm not sure). They use the piezo-electric effect to provide voltage multiplication.

Also, there are some more advanced 9v batteries available that are quite expensive, but provide more energy than the usual drug-store alkaline.

If there's room, use more than one 9v battery, or use six AA cells.

 

[boreholelogger]

Its all good I just designed another circuit that can output up to 2500V @ 30uA from a 7.7V @ 12mA input supply.

 

[boreholelogger]

I ended up getting a custom built ferrite transformer 55 Turn to 2000 Turn, with a 12 Turn feedback built in. I used the feedback to run a transistor to switch the input to the 55 Turn coil with the supply from an LM317T. This then stepped the voltage up dramatically and I just added diode and capacitors for the voltage multiplication circuit and a filter circuit on the output to reduce the ripple to 50mVp-p.