150 vdc regulated power supply 1-2 amps

[Pbubis]

Can anyone help me build a current regulated power supply of 150 vdc with output of 1-2 amps?

 

[jackorocko]

Linear? What is your input voltage?

 

[Pbubis]

Yes, it must be a linear supply using input voltage of 120vac. I built the fist stage using a large toroid transformer, bridge rectifier and filtering condensers of 8000 mfd 450vdc. The problem I'm having is to regulate the current down to 1-2 amps. Hope you can help me.
Perry

 

[(*steve*)]

The problem I'm having is to regulate the current down to 1-2 amps.

OK, I assume you're not particularly experienced.

You're building a voltage regulator, so you don't regulate the current (although you might limit it).

What's your experience with electronics?

What is this going to power (alternatively specify the required output in terms of min/max voltage, ripple, transient response, etc)?

You do realise that this power supply could be very dangerous, yeah?

edit: *why* must it be linear?

 

[Pbubis]

Steve:
Thank you for your response. As far as my electronic experience is concerned, I am an experimenter who has built all sorts of circuits. I'm very comfortable working with electricity. I have a great respect for it. I do understand the principles of working with high voltage. My use for this power supply is to power a hydrogen generator. My experimenting has led me to use this type of power supply. Volts are necessary and a current rate of 2amps works great. I need to build this power supply in which I can reasonably maintain ~150vdc and be able to control current. Can you help me?

 

[(*steve*)]

I can't imagine why you'd need 150V for that, but <shrug>

I also can't imagine you need perfect DC.

I remember many years ago seeing a regulator that used an SCR to let through a half cycle whenever the output voltage fell below a set point. It had the advantage of generating very little heat as it was essentially very slow PWM controlled by the mains frequency.

SCRs with this voltage and current rating are easy to get hold of. (wondering if you could use a SSR for this...?)

Controlling current? you can't maintain a voltage and control current. Do you mean limit current?

 

[Pbubis]

Steve,
Believe me that 150 vdc works the best. I run this voltage thru a mosfet being pulsed at resonant frequency of generator. I guess what I want is to limit the current while maintaining the voltage. Can you show me a schematic of your idea?

 

[(*steve*)]

You cannot maintain the voltage whilst limiting current unless you modify the load to change its resistance (or reactance)

Please don't tell me any more about your load. If I suspect that you're building some magical hydrogen generator that can extract more energy from the water than being put in then I may be forced to conclude something...

If your load is inductive then PWM can be used to limit current. In this case there is little need to regulate the voltage as long as it does not exceed the limits on any of your components (chiefly your mosfet).

If your load is resistive, you could add a series inductor and a flyback diode. This will essentially turn your PWM into a switchmode power supply. If you alter the duty cycle based on current, you have essentially created a high efficiency constant current source.

 

[Pbubis]

150 vdc power supply

Steve:
Thanks for your thoughts. My load is resistive. I can measure 120megs resistance between plates. Can you direct me to a PWM unit that can handle 150 vdc? What size inductor should I use in series with the load?

 

[BobK]

If you have a resistive load of 120MOhms, it will take a lot more than150V to put 2A through it!

Bob

Edited to add: Oh, and resistive loads do not have a resonance.