// Mother of all Bench top Power supplies ( DIY Project )

Sorry for the slow updates on this project allot going on.

So I spent the day down in the Lab pounding out the wiring.

Here is my progress.

( You can skip to the end if you just want to see a video of it in operation )

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Started with the Voltage meter first.
I built a custom dual stage voltage divider the DPDT switch will turn on only the divider that is requested, that way the lower value divider does not have to dissipate a ton of heat at the high voltage. I also have trim pots installed for slight adjustments.


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Here is the second layer, the 120/240V logic circuit. the Circuit breaker on the front are only for show, the real work is done by the 30amp Mercury relays on the left side. The indicator lamps turn through the relay, so they will only light if everything in the system is good and voltage is passing. The system will also prevent cross shorting the 120 and 240 there is a relay that will make and break the connections to keep things safe ( in the event both breakers are on it will default to 240 )

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Closeup of the Dual divider network.

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Here was the fun part, fitting (2) 20amp Variac's in there as well, Was a snug fit but works. there is a contactor that will add or remove the Variac from the line as requested.
the tricky part was to make a 120V Variac work on 240 I had to give one end of the coil a neutral reference, this works fine but if you bypass the output, can can create a line short, so the contactor has to remove the neutral reference and then short past the variac to bypass it.

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The top of the box was drilled to allow the Variac shaft to exit the top.

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Sadly there was just not enough room to run it out the front. so the top will do.



And here is a Video of it in operation.

[video]http://youtu.be/8kiuXyC4akw[/video]


Whats left is to add the Hi/Low voltage setup for the large transformer, and the AC/DC selection circuit.

When that is all done, I then can build in the Current limiting array.

It looks well made.
Where is the tank of liquid nitrogen for cooling the thing??

Very nice!

I don't see any outlets, jacks or binding posts - how are you getting the power out?

duffy said:

Very nice!

I don't see any outlets, jacks or binding posts - how are you getting the power out?

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Its output is lots of heat.
100 years ago, live theater used huge and hot variacs as light dimmers.

duffy said:

Very nice!

I don't see any outlets, jacks or binding posts - how are you getting the power out?

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Thanks!

When done there will be a large 100 Amp breaker on top with 1/0 binding lugs for my projects to connect.
This is just the start

audioguru said:

Its output is lots of heat.
100 years ago, live theater used huge and hot variacs as light dimmers.

Click to expand...

The 3,000 watts of current limiting resistors will be nice in the winter haha

As many of you know it takes moments to make something work but weeks to make it look good. I am forcing myself to not go nuts on wire management. I would like to use this some day soon

Well, I could not sleep so I went back down to the Lab to work some more,

I got Stage #2 Done the AC/DC selection section.

This one seemed to take longer for I had to work with all 4AWG wire, so just more work haha

Again this is another dense heavy stage.

So here is shortly after I started, the holes are in place for the Bridge.

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I found some isolation mounts from an old high vacuum Cryo torr pump, there where electrically isolated as well! So bolted them up.

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It is mounted to the side wall and the lower floor, with 3 mounts. so it is rock solid.

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There happened to already be a vent in the case so I used that to help vent the Bridge.

The Diodes in the Bridge rectifier are ratted for continuous 200amps and good up to 600V so they should be a good match with 0-240 and 100amp.

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I happen to have 250 feet of 4 conductor 4AWG ( it is not as cool as it sounds, it is very heavy and fits into almost nothing! haha )

So I used this to wire up this stage, for when ( low Volt ) is selected there is a potential of 0-48V at 100Amps. so I wired it all with 4AWG

Why RED and WHITE? you may ask, well the output can be AC or DC as well as 220 or 120 or 48V so I chose red so you know what one is + so the other is Neg and when AC the white will let you know what is neutral so the other is Hot, and when at 220V AC the Red will let you know what leg is the Hot 220. Well, it all made sense in my head haha

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And there she is all wired up. I even installed a current scale on the front of this stage that is 0-10Amps that will show how much power just the control circuit is pulling, as in all of the contractors and lamps. ( so I know that plus my output can not be more then 30amp at 240 or my main breaker will trip )

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Here is a shot with it wired up for testing.

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This is the transformer I plan to use, it is from a huge backup UPS that was installed in Kaufman's it is good for 48V out at around 200~ Amps it is 1 foot square and also has a 240V primary. Oh and did I mention it weighs a ton!!! haha




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There is a sneak peek at Stage #3 the control brain of the system that will select Hi/Low volts as well as handle safety logic. Allot of wiring fun there, that will wait for another day haha

Also forgot to mention the Large fan will kick on automatically when you select DC to cool the bridge down.

I think I may cut this out of Vinyl for the Switch

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Few will get it haha

DJDAudio said:

I think I may cut this out of Vinyl for the Switch

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Few will get it haha

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Heavy Metal rock and roll for 38 years? They are from down under? They still play.

audioguru said:

Heavy Metal rock and roll for 38 years? They are from down under? They still play.

Click to expand...

You got it

Working through a new problem now, my current meter is this,

http://www.datasheetcatalog.org/datasheet/lem/LA100-S.pdf

I plan to use it for the final output and want to couple it to a analog 0-100 Meter for current, the meter is 1mA Full Scale deflection. I built a voltage divider but the output appears to not be linear.

For example,
10Amp in meter will show 5amp
20amp in meter will show 20 amp
35 amp in the meter will show 60amp.

I may have to build a switching power supply for it to be happy...

Always something haha.

I got most of the current monitoring done and installed, I also got the AC/DC section installed and wired up this evening.

I could not resist the urge to try it out, With a 12Amp ( 1,400 Watt) Resistive Load.

VIDEO:

And here are some close up pictures,

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The gauges have some fun names, one is an 'Energy Analyzer' the other ' Dead Time' Have to love recycling old equipment

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The lower 0-10Amp AC current meter for the Control Side.

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and a random Artsy photo.

As you can tell I got the Current meter working, Turns out the output from the current transformer is 0-8VDC not 0-15V Full scale, so had to re adjust my math to get it to work.

Small Update,

Installed the Terminal strips, and got a nifty little circuit mounted.

I have had this device kicking around for years, it is for adding a ground to a system, and will let you know if you have a good ground or not.

So I took it apart and built it into my system.

( Green ) is ground is good )
( Red ) Ground is bad.

Most places I will take this the welder plugs do not have ground, so this will let me know, and I can run an auxiliary ground.

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This is an amazing thread. Probably a bit overkill for microcontrollers eh?

I like all the purty gauges, very nice job on the wire routing and layout too.

Nice pictures and fantastic job so far. Huge project that is probably beyond most members here. I wish you well.

We will need more pic's once all is done and dusted and working: D

Cheers,
TV TECH

Do yourself a favor and re-label those switches and meters as soon as you can - or at least take a picture now and add some text. On projects less complicated, a few months down the road I'm always, like, "WTF did this do?"

duffy said:

Do yourself a favor and re-label those switches and meters as soon as you can - or at least take a picture now and add some text. On projects less complicated, a few months down the road I'm always, like, "WTF did this do?"

Click to expand...

Haha, I am already forgetting

I plan to flat black everything, and white vinyl letter everything with old 'meter' font.

Ok another Update, I got Stage #3 Completed.

While working with the Circuit I found some ways to simplify it with less relays, so it looks less complicated, but in a way it is more

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With the help of a friend of mine we got the 80lbs Transformer mounted.

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And here is the Control section The hard part was designing a dual sensing volt meter for both low and High volt ranges for the input to the Volt meter without crossing the circuits.

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Here is the large 100amp contactor I will use to activate the low Voltage section.

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Bolted in and Wired up.

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here is my 50Amp Choke that also happens to work as a nice current shunt for my output current meter.

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And here it is everything in place and ready for wiring and testing!

... Let the fun begin.