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I make the rwilsford07 DC-DC HV Boost Converter and it only gives 32 volts Answered

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I want to build the DC-DC HV Boost Converter but it only gives 32 volts from a 9volt input.
The output voltage depends on the number of oscillations?
I am using coilcraft PCV2-394-05L and the mosfet 75N75

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user
iceng (author)2011-11-14

I pointed out the 75V MOSFET should be 600V per the author rilsford07...

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Kurt Gerhard (author)iceng2011-11-14

When I buy it, I think that it was 750 volts 75amp

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iceng (author)Kurt Gerhard2011-11-14

If you read the comments,  rilsford07 later went to this device.
Did you forget to build it or just forget to draw it ?

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The MadScientist (author)2011-11-15

Use an IRFP460 instead it has a voltage rating of 500V.

If that still doesn't work wind your own inductor with thicker wire.

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Kurt Gerhard (author)2011-11-14

I forgot on the schematic the capacitor (1mfd) below the 6 and connected to ground

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steveastrouk (author)2011-11-14

390uH coil, maximum of 3.5 A, and on 12V means you need to run at a frequency of about 30K by my reckoning.

Steve

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iceng (author)2011-11-13

You do know how and why it works ?
Then you can see how to improve on your own.

A

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Kurt Gerhard (author)iceng2011-11-13

yes, but i dont know why it give so low voltage.
The output voltage depends of the Hz?

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iceng (author)Kurt Gerhard2011-11-13
Not really the repetition increases output average current.

This works by shorting the inductor to ground and starting a magnetic field buildup
known as dI/dt ( rate of change of current ). Also the third most important.  As Steve said,  voltage is important because it decides your coil current ..
  • Now this is the second most important :  The current must be stopped before the inductor field can begin to saturate and level off...
  • This is The MOST IMPORTANT : The speed with which your electronics Turns-Off ( interrupts ) the current knownas dV/dt  ( rate of change of voltage ) will determine the peak Voltage. Because an inductor is like a a river suddenly stopped, the flow will pile up increasing pressure ie_voltage.
Now a problem for you,  this DC-DC HV Boost Converter is made to generate 100 to 500 output volts BUT your mosfet is only 75V and probably crippled by your circuit in
the first turn off.  Which is why rilsford07 used a 600 Volt MOSFET. for this circuit.

Hope this helps.

A

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steveastrouk (author)2011-11-13

A 9V rectangular battery ?

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user

no, I use 6 1.5 volts batteries

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steveastrouk (author)2011-11-13

This design relies on batteries with very low output resistances. The orginal notes also point out that you need at least 12V.

Steve

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user

ok, thanks, I will try that

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