Simple Bench Power Supply 10A

ortiko · Nov 1, 2014

audioguru said:
Many LM393 comparators cannot be used in your circuit because its minimum output low current is only 6mA. Your circuit has an output current of 14.3mA.
It is a dual comparator. Do you know how to disable the unused comparator?

No i do not.
Can you explain more please ?

This is my first attempt with LM393 and general with comparator...

audioguru · Nov 1, 2014

I do not know what the comparator will drive.
You made many mistakes on your schematic that I fixed except for R5.

KeepItSimpleStupid · Nov 1, 2014

Comparitors usually have open collecor or open drain ouputs, so thay can't source current. See the datasheet here: https://www.google.com/url?sa=t&rct...=ZFfSvCgmjZNjfhsK0J5DSw&bvm=bv.78677474,d.cWc

You have to design for 6 mA or the minimum sink current thats guaranteed.

Disabling, basically means you should pick inputs which would result in 0 output in this case. Because of the high input Z, you should have the comparator inputs somewhere. Vcc and ground would be fine, but you would RATHER the output transistor to be off, not on. Usually a resistor is inserted in series with the In+ and In- lines as well. Whatever you have handy or used elsewhere in your circuit, e.g. 10K

audioguru · Nov 1, 2014

KeepItSimpleStupid said:
Usually a resistor is inserted in series with the In+ and In- lines as well.

Why? The input current is very low and the inputs of this comparator work perfectly at 0V.

Nigel Goodwin · Nov 2, 2014

ortiko said:
In my LTspice Circuit R4 is for hysteresis if i am not wrong

As it doesn't go to the output, then no it's not

Connecting it properly to the output would work, but your resistor values all seem rather low?.

ortiko · Nov 4, 2014

audioguru said:
I do not know what the comparator will drive.
You made many mistakes on your schematic that I fixed except for R5.

The 14.3Volts is the desired volt to change from one transformer to the other(this comes from power supply output voltage 0-32 Volt)
5 Volt is for reference only
R3 is the output resistor. I suppose for relay a transistor will be needed ?

ortiko · Nov 4, 2014

Nigel Goodwin said:
As it doesn't go to the output, then no it's not

Connecting it properly to the output would work, but your resistor values all seem rather low?.

Have changed the circuit as below.
When i run it and use the red voltmeter to take measurements i only have 1v ?
What have i done wrong? I think it has to do with ltspice config...

audioguru · Nov 4, 2014

Your circuit is still completely wrong:

ortiko · Feb 9, 2015

Well i am back with this project.
Sorry for long absence but had many work and some more things to do
I now thanks god found the time to continue this project

I decided finally not to use a voltage comparator because of absence of time and want to finish this project.
So as i have described at earlier post i will use the switch for low and hi voltage transformer.

Below is a little progress i have done with it today !

Must mention that i did not drill the holess yet for the potentiometers...

Have it in mind to paint it but haven't decided the color
Any ideas what color to paint it ?

KeepItSimpleStupid · Feb 9, 2015

Tektronix blue. Somebody sells the paint.

moty22 · Feb 9, 2015

The comparator isn't needed for hysteresis because the relay has hysteresis. Alternatively you can get positive feedback using one resistor from the unregulated DC to the base of the relay drive transistor.

ortiko · Feb 10, 2015

KeepItSimpleStupid said:
Tektronix blue. Somebody sells the paint.

Can you post a link with picture please ?

ortiko · Feb 10, 2015

moty22 said:
The comparator isn't needed for hysteresis because the relay has hysteresis. Alternatively you can get positive feedback using one resistor from the unregulated DC to the base of the relay drive transistor.

Will not use a comparator
Thanks anyway

ChrisP58 · Feb 10, 2015

moty22 said:
The comparator isn't needed for hysteresis because the relay has hysteresis. Alternatively you can get positive feedback using one resistor from the unregulated DC to the base of the relay drive transistor.

Magnetic relays do have hysteresis, but make/break delta is very wide, and probably not useful for this application.

ortiko · Feb 15, 2015

Have installed the switcing power supply for the 5V usb ports and led's Hi Low indication

Have put almost everything together and soldered 220V wires to the transformers,power switch, fuse transformer switcher...

And Video from the Hi Low LED indication

I hope to finish this soon!
The PS front panel and cover will be painted tomorrow i hope. Will post the results

ortiko · Feb 19, 2015

Sanding and will be painted tomorrow ...

ortiko · Feb 19, 2015

Primers and re scrubbing before the final color ...

Almost done!
Have the final painting and installation of the blower...

MrAl · Feb 20, 2015

Hi,

Very nice. Where did you get the case?

ortiko · Feb 20, 2015

Hello

This case is shuttle pc with dead mo/bo a friend gave me

ortiko · Feb 23, 2015

Painting Job is DONE !

What dou you think? Is it gona be nice looking ?

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