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Offline kolias

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Re: Power Supply Unit
« Reply #40 on: January 11, 2011, 09:26:44 AM »
The attached is part of the last page from the CambellDesigns document and I have some questions:

1- When he says all ground wires should be attached to one point, does this mean AC and DC ground?

2- Then he says to run a wire from the + terminal on one of the capacitors to a terminal strip because later    you will run a wire from the terminal to the fuse block. What this fuse is for?
Nicolas

Offline Hood

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Re: Power Supply Unit
« Reply #41 on: January 11, 2011, 01:54:48 PM »
I am not sure  about the mains wiring in North America so dont really want to comment too much regards question 1 but dont get confused with the neutral of an AC circuit and Gnd. Your transformer will likely only have two wires on the primary or possibly 4 but they are live and neutral and none is a gnd wire. If your mains has live neutral and gnd then you would normally have the Gnd connected to the Gnd stud.


Regards question 2, the positive wire from the cap will be the positive you use to feed your drives, the 0v coming from the negative terminal on the capacitor. The positive is fused in that example but I am wondering if that is actually a good idea and will let others that have more knowledge comment on that.

Hood

Offline kolias

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Re: Power Supply Unit
« Reply #42 on: January 11, 2011, 03:26:32 PM »
I have two pilot lights rated for 110VAC which I want to install on the control station for my CNC. Would they work if I supply them with 40VDC?

Also I have a toggle switch rated 10A, 250VAC which I want to control 8 LED lights. Would this switch work if I connect it to 12VDC?

I dont confuse the ground, neutral and line on the 110V circuit. I just wanted to know if I can connect the ground from the 110VAC along with the ground (Black wire) from a DC circuit

Well the store close by does not have any toroidal transformers neither rectifiers but they do have a large selection of capacitors
10000uf, 25V, $3.99 (that thing is HUGE)
8200uf, 25VDC, $2.99
5500uf, 25VDC, $1.99

When I buy the capacitor(s) how do I secure them to my board? I noticed on the .pdf document from Cambel that he has some kind of pipe clamps at the bottom. Do I buy these clamps separetly?

Anyone knows an online store to buy the toroidal transformer and rectifier?
Nicolas

Offline Hood

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Re: Power Supply Unit
« Reply #43 on: January 11, 2011, 04:49:17 PM »
You can buy the capacitor clamps or secure with cable ties(zip ties?) or even a dab of silicone sealant on the base and stick them down.
Hood
« Last Edit: January 11, 2011, 04:52:05 PM by Hood »

Offline BR549

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Re: Power Supply Unit
« Reply #44 on: January 11, 2011, 07:28:16 PM »
MAke SURE on your caps that you over rate the voltage rating. Do not use 25dcv caps on a 40 vdc system.

Just a thought, (;-) TP

Offline kolias

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Re: Power Supply Unit
« Reply #45 on: January 11, 2011, 08:32:10 PM »
Thanks for bringing it up, a very good tip
Nicolas

Offline kolias

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Re: Power Supply Unit
« Reply #46 on: January 12, 2011, 08:36:22 AM »
The conclusion so far is:

1) I would like to know if I can connect the ground wiring from tha AC along with the Ground (Black) from the DC (I plan to use a metal bar on my board and connect the AC ground plus the DC black wire there)

2) It seems that toroidal transformers are not easily available. Searching on the web I found no places where I can purchase them and eBay does not have the size I want. Antek has them but they are out of stock. Anyone knows where I can buy them?

3) Rectifiers seems that is easy to purchase

4) As I understand now, the capacitor has to be a multiple of 50VDC or perhaps more? Anyone can suggest a safe combinations (uf / vdc)?
Nicolas

Offline kcrouch

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Re: Power Supply Unit
« Reply #47 on: January 12, 2011, 10:44:12 AM »
Signal transformer has lots of items that will do for you. signaltransformer dot com
They can make up any toroidal transformer that you need as well as having lots of other transformers in stock. Check out their MPI series too.
Kenny
Having way too much fun! Something must surely be wrong.

Offline Hood

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Re: Power Supply Unit
« Reply #48 on: January 12, 2011, 11:00:19 AM »
The conclusion so far is:

1) I would like to know if I can connect the ground wiring from tha AC along with the Ground (Black) from the DC (I plan to use a metal bar on my board and connect the AC ground plus the DC black wire there)
My commercial lathe and mill had/have the AC Earth (as we call it) connected to the stud, DC 0V is not as far as I can recall (possibly internally in the power supply the connect to earth)but all shields are.
2) It seems that toroidal transformers are not easily available. Searching on the web I found no places where I can purchase them and eBay does not have the size I want. Antek has them but they are out of stock. Anyone knows where I can buy them?

I am from the UK but every place that sells electronics in the UK sells toroidal transformers so I would imagine the USA places such as DigiKey would also.

4) As I understand now, the capacitor has to be a multiple of 50VDC or perhaps more? Anyone can suggest a safe combinations (uf / vdc)?


As was said by me, Rich and lastly Terry you need the voltage to be above the DC voltage of your supply, it can be as high a voltage rating as you can get but dont go lower and as Rich pointed out best 20% higher than your supplies output. Capacitance is similar, except it can be what you calculated (dont need the 20% more that the voltage does) or higher but again never lower.

Hood

Offline kolias

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Re: Power Supply Unit
« Reply #49 on: January 12, 2011, 08:41:03 PM »
Ok we are getting somewhere now.......

Gerry helped me to locate the transformerand it looks good
http://www.mpja.com/prodinfo.asp?number=7846+TR

For the capacitor I will get one from the store in my area, around 30 – 50 VAC, 10000 – 20000uf

For the bridge rectifier the choices I see from the same store as the transformer are:
400PIV, 15A
1000PIV, 15A
50PIV, 25A
400PIV, 25A
50PIV, 35A

Dont know what PIV means, is my choice in one of the above?
Nicolas