power supply

[peter g]

hi all, i want to build this circuit, but don't want to use the power supply indicated on the attached schematic. can someone come up with a 0-100vdc p/s i can use instead? also, where to attach it? thanks.

 

[danadak]

This might help :

WEBENCH® Power Designer | Overview | Design Resources | TI.com

Design more quickly and easily with WEBENCH® Power Designer. WEBENCH® Power Designer creates customized power supply circuits based on your requirements. The environment gives you end-to-end power supply design capabilities that save you time during all phases of the design process.

www.ti.com

Regards, Dana.

 

[peter g]

thanks for your response, but didn.t find what i wanted.

 

[Pommie]

That appears to run of a 9V battery supply. It generates the 100V itself.

Mike.

 

[dougy83]

The schematic you attached generates the 10V-100V supply, depending on the switch setting. To make your own supply, the normal way would be to use a SMPS IC and wire up something similar to that in the schematic. Alternately, you could get the microcontroller to drive a transistor/inductor/diode and regulate the supply.

If you didn't find what you wanted in the SMPS design page above, what are you after?

 

[peter g]

the design page shows p/s to only 48v. i want 100v. what about a linear supply?

 

[Lightium]

You could use an ne555 to drive a coil to 100 volts. Not sure about the current.

 

[Pommie]

Why do you want to design a power supply? What's wrong with the one in the schematic?

Mike.

 

[peter g]

the p/s ithats indicated requires winding a special transformer. i'am trying to avoid that.

 

[ChrisP58]

the p/s ithats indicated requires winding a special transformer. i'am trying to avoid that.

Well, technically it's a coupled inductor, but it is a custom part.

What info is given about T1 in the article? I can imagine it being a very simple item to build. Take core X and add two windings. Once the materials have been gathered, it'd take only a few minutes to wind by hand.

 

[dougy83]

the design page shows p/s to only 48v. i want 100v. what about a linear supply?

The schematic seems to be showing it going to 100V. The split inductor allows a higher voltage than the MC34063 could handle on its switch/collector pin.

the p/s ithats indicated requires winding a special transformer. i'am trying to avoid that.

If you want to just use an off-the-shelf inductor, you'll want to use an external switch (FET/BJT transistor) that can handle the 100V. You can drive it with the MC34063 shown in the schematic, or use a different IC, e.g. UC3843.

 

[Pommie]

I'm assuming that T1 is a kind of autotransformer. Could that simply be wound on a ferrite core?

Mike.

 

[rjenkinsgb]

From some photos I've found, the inductor is just a pot core around 25 - 30mm diameter (based on the proportions of that relative to the LCD bezel).

They are very easy to wind and use, just count the turns on to the bobbin as you wind it then put the ferrite half cores around it. I've used dozens of them in various projects over the years.

Example parts:

Ferrite Pot Cores for Inductors and Power Supplies : Coil Winding Specialist, Inc.

Coil Winding Specialist, Inc. : Ferrite Pot Cores for Inductors and Power Supplies - Products Specification & Properties About Us LOG IN HOME Other Services coil, ecommerce, open source, shop, online shopping, store

www.cwsbytemark.com

Ideally you should find a parts list (or buy a copy of the original article) that gives the correct core material or type number, as there are several variations in each size, with different magnetic properties.

Using the correct, original transformer parts is by far the easiest way of getting that circuit to work - and it does explicitly say in numerous places that the test voltage goes up to 100V with that design.

A ferrite toroid core may work as an alternative, but without knowing the material type of the original core I would not have a clue what to suggest..

 

[peter g]

the original pot core is ferrite.

 

[rjenkinsgb]

the original pot core is ferrite.

Yep, but there are various grades of ferrite with different magnetic properties relating to inductance and suitable for different frequencies. Also, the cores are made with different air gaps, which drastically change the inductance per turn of the winding.

 

[Nigel Goodwin]

the original pot core is ferrite.

And only has 60 turns, wind yourself a transformer using a ferrite pot core - you really need a transformer to make the 100V, and that circuit looks excellent.

 

[Lightium]

the p/s ithats indicated requires winding a special transformer. i'am trying to avoid that.

Can you state your reason(s)?

 

[peter g]

i think its unnessiarily complicated. there should be an easier way. what about using the attached supply?

 

[Nigel Goodwin]

i think its unnessiarily complicated. there should be an easier way. what about using the attached supply?

It's vastly inferior, and probably more complicated, but feel free to give it a try.

There's less parts in the original circuit, other than those for setting the output voltage - the 555 one isn't even regulated.

 

[peter g]

where does one get a ferrite pot core?