0-300V DC signal generator

For a one-off, a CFL inverter, a diode, a capacitor, and a 300V shunt regulator.

Cheers

Phil Hobbs

You say, "...generate a DC voltage between 0 and 300V?"

What sort of granularity/ripple, do you need?

Burst mode flyback probably would do the trick... probably would need current control as well. ...Jim Thompson

Things aren't matching up here. Signal generator or power supply? Is your 24V the available power rail, or are you amplifying a 0-24V signal?

If you are looking for a 0-300V _power supply_, to be derived from 24V, without any special frequency response needs, I would think that a flyback circuit would get you there.

Colcroft-Watson multiplier would probably be the easiest.

Vladimir Vassilevsky DSP and Mixed Signal Designs

Push-pull driving transformer -> voltage doubler with about an 8:1 xfmr turns ratio (CT primary and secondary)?

"... generate a DC voltage between 0 and 300V."

Note the "between" which, to me, implies a variable output. So transformer drive is not the best of solutions.

That's why I suggested burst-mode flyback.

But you might scarf up a transformer driven by an audio amplifier, and vary the amplifier drive. ...Jim Thompson

In one word: SEPIC. You can use pretty much any boost converter chip for that.

That is only really a concern for high power situation. 300mW doesn't quite qualify as high power :-)

A *what*???

Ah, Cockcroft-Walton, I suppose.

Jeroen Belleman

Here's a 0-900 volt thing I did once:

At 300 volts, you could use some photoflash parts. Linear Tech has a flyback photoflash driver chip with appnotes. There are also throwaway-camera flash schematics on the web.

You could do 24-to-300 as a single-inductor or maybe center-tapped-inductor boost converter, too, with stock parts.

I did one supply that made about 120 volts unregulated, using an available square wave into an ISDN transformer and dual diode doubler. I dumped the 120 DC into a depletion mosfet to get a constant current, and shunt regulated that.

Whatever. A bunch of BAV99s and ceramics and 555 to drive/regulate. No need for custom or semi-custom magnetics.

Vladimir Vassilevsky DSP and Mixed Signal Designs

One of many circuits that'll do;

I'm also fond of boost-flyback circuits like this one,

And numerous chip based solutions (interal or external switch).

Both of these are wound for about half the voltage, obviously you'd double the turns ratio and feedback resistors to get there. No problems with parasitic capacitance, at least at this level.

For off-the-shelf-ness, you could try shanking a camera photoflash circuit. The current may be lower, and the supply voltage too low, however. And you'd have to add your own regulation.

Tim

I am not a fan of CFL inverters used this way; the design is to produce high voltage at very little current voltage for "first strike" to produce ions), and then produce current at low voltages (typically ionization potential of Hg = = 32V). I seriously doubt that any "reasonable" current can be maintained at

Il 03/05/2013 20:26, Jim Thompson ha scritto:

I haven't yet such a details but I think 7-8 bit should be enough with a ripple less than a LSB.

I'll looking for some app notes. Thanks Marco

Il 03/05/2013 20:37, Tim Wescott ha scritto:

I said "signal generator" because the output current is very small, so in my mind it's not a "power supply".

The power rail. The output voltage is set by a microcontroller.

So what the difference between a 0-300V power supply derived from 24V and a 0-300V DC generator derived from a 24V? I ask this to use the right terms.

Thanks Marco

Il 03/05/2013 23:21, Vladimir Vassilevsky ha scritto:

I knew it as voltage multiplier (composed of a cascaded half-wave doubles).

I will do some simulation to understand how it works with such a large span of voltages.

Of course avoiding magnetics is a great thing ;)

Marco

"Marco Trapanese"

WTF constitutes a " signal" in your book ?

Using a "DC generator" is one way to achieve it.

BTW:

You need to say if the 300V supply needs to have ( galvanic) isolation from the 24V one.

Makes a big difference to the topology.

.... Phil

Il 04/05/2013 09:03, Phil Allison ha scritto:

A voltage (or current) with negligible power. It is used to control something rather than power something. Am I wrong?

The galvanic isolation is welcome but not mandatory. Of course there must be protection against over-current and short-circuits.

Thanks Marco

"Marco Trapanese"

It is wrong to use the term for things that do not.

Wot a code scribbler.

... Phil

Il 04/05/2013 09:31, Phil Allison ha scritto:

Well, that voltage *does* contain information! It's the output variable of the system.

Marco