Seeking Circuit for Step-up Power Supply

[Graeme Dennes]

I am seeking a simple step-up power supply circuit which takes 6V DC (four
dry cells) as input, and outputs 100V DC at about 10mA.

I have not had success to date with searching the 'net, manufacturers'
application notes, etc...

TIA for any links, references or ideas.

Graeme Dennes

 

[budgie]

On Thu, 23 Oct 2003 12:32:13 +1000, "Graeme Dennes"
<gdennes@ihug.com.au> wrote:

I am seeking a simple step-up power supply circuit which takes 6V DC (four
dry cells) as input, and outputs 100V DC at about 10mA.

I have not had success to date with searching the 'net, manufacturers'
application notes, etc...

TIA for any links, references or ideas.

You could do a simple boost cicruit using any of a number of
switchers, as long as the chip drives a switch (FET or bipolar) with
adequate voltage rating.

Do a google search for "simple switcher" which should pull up the free
software for the NatSemi LM257x family. These provide a low-count
result, and the chip costs $7 or so.

The biggest issue is getting the magnetics worked out. For a smaller
step-up ratio, a standard boost config with a series inductor would
work, but I'd be a tad shy about a 16:1 step-up in boost. A flyback
type using a transformer is more suited at that sort of ratio.

The MC34063 and its clones are able to do fairly low-count boost and
buck with the caveat listed above. For example, on my latest project
( a custom EPROM progger) I step up the 12V to 28V and then produce
the regulated Vpp supplies from that. But 100V?

 

[William Bond]

Mr. Dennes;
I think I may be able to help you out a little bit, you will not be able to get exactly 100vdc as you hope, but you can get 96vdc at 12.5mA. First you need to have a multivibrator circuit.
follow the link below for multi vibrator circuit
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/T555.html
RA=1ohm
RB=1k ohm
C=10 microfareds or .00001

take the output of 3 above and insert it into the voltage doublers on link below
http://home.golden.net/~kpwillia/mult.htm

You will need to have 4 doubler circuits to get your 96 volts from 6 volts. if you go one more doubler you will have 192volts at 6.25mA.

I hope that this helps.

William

 

[John Crighton]

On Thu, 23 Oct 2003 12:32:13 +1000, "Graeme Dennes"
<gdennes@ihug.com.au> wrote:

I am seeking a simple step-up power supply circuit which takes 6V DC (four
dry cells) as input, and outputs 100V DC at about 10mA.

I have not had success to date with searching the 'net, manufacturers'
application notes, etc...

TIA for any links, references or ideas.

Graeme Dennes


Hello Graeme,

What are you building/doing with this power supply?

What came to mind straight away was LT switchercad 3.
You can download the program here.
http://www.linear.com/software/
I tried it but even 80 Volts out was pushing it too much.

I had a look at the National on line Web bench.
but that was no good either.
http://www.national.com/appinfo/webench/scripts/my_webench.cgi/
100 volts is asking too much here also.

Old two way radios, have a transistor receiver and valve
transmitter output stage. A transistor DC to DC converter
is used to get DC for the valves. These are just a power
push pull oscillator and step up transformer working with
12 volt input.

While you are rooting around with this stuff you could go
back in time even further and find an old FJ Holden 6 volt
car radio and pull the vibrator power supply out of it.
Only kidding!
I came across an old vibrator in my junk the other day
and agonised about chucking it out. I coudn't.
Brought back memories of when I was broke and
prising open the can to clean the contacts rather than
buy a new one. They were expensive.

If you search through old Electronics Australia magazines
and similar you will find articles on CDI ignition systems.
To generate a high voltage the same push pull oscillator
idea and a ferrite potcore type transformer is sometimes
used. You could experiment with the values of the feed
back components and use a different turns ratio on the
transformer to make the power supply run at 6 volts and
give you the 100 volts out. The pot core bobbins are
very easy to wind, and the cores are held together with
one screw and nut. Experimenting is easy.

I just had a quick google for you and came across this.
http://www.i4at.org/lib2/inverter.htm
This inverter produces a rough AC around 50/60 Hz
Use the circuit as a guide.
Reduce the values of R3 & R4 for 6 volt operation. Experiment.
Change CI & C2 to make the circuit operate at a higher
frequency. Experiment again.
Find a small transformer to suit you.
Rectify and filter the output.
You could even add a regulator stage if you wanted too.

Have Fun,
John Crighton
Hornsby