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Arcstarter

Thu Feb 12 2009, 09:47PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

I would like to make a full bridge (finally) with this new double sided copper clad that was given to me by Tribologist (thank you Ulf!!!!). I could easily make it myself, but i do not know how i should use the bottom side. how should it be used? With out using the bottom side, i could make the full bridge easily, but as long as i have two sided, why not use it to its full potential?

I have been looking on google, but i cannot seem to find anywhere that shows every part. A couple pictures or a short description would be appreciated.

Also, i am planning on using those PCB screw terminal things, for easy replacement. I would just put them on the underside of the board, and cut a hole around the copper so it did not short. Then i would just cut the hole, and solder to the top side. is that a bad way, or is there a better way? I could not see what is wrong with it.

EDIT: fixed spelling

Tom540

Thu Feb 12 2009, 11:04PM

Banned on 3/17/2009.
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Whatever you make on top do it the same on bottom and then drill holes and feed through wire to double it up.

Anon01

Thu Feb 12 2009, 11:07PM

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Ground plane.

Mike

Thu Feb 12 2009, 11:52PM

Registered Member #58 Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317

First it would help to know what transistors you are using?
Mini bricks? To-247? Bricks?
I've seen quite a few brick designs on the board and if you search the old.4hv.org you can find some to-247 layouts as well. Also steve ward had a cool mini brick layout ive used before.

Arcstarter

Fri Feb 13 2009, 01:02AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

This is why i asked. Should i use ground plane or double it up? I am not looking for current carrying capacity here, i am only using super TO-247 mosfets. I have only really seen it be used as a ground plane, i think. Sounds easy, just gonnect sources to ground plane (and the gate zeners and GDT.).

GeordieBoy

Fri Feb 13 2009, 01:27AM

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If you want to use double sided copper clad board, but don't need to route seperate nets differently on each layer, then just copy the same power traces on top and bottom to reduce DC resistance. Ground planes are useful for fast digital, RF and analogue applications, but can actually cause problems in power electronics applications. You certainly dont want a groundplane underneath the mid-point nodes of bridge legs. Any additional capacitance to ground here is detrimental to efficient operation of the H-bridge and makes noise problems worse!

A more effective use of the two layers is to make the top layer predominently DC bus positive, and the bottom layer predominently DC bus negative. Then you can use large areas to carry the supply currents and the capacitance between the two layers helps reduce noise.

-Richie,

Arcstarter

Fri Feb 13 2009, 01:48AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

A more effective use of the two layers is to make the top layer predominently DC bus positive, and the bottom layer predominently DC bus negative. Then you can use large areas to carry the supply currents and the capacitance between the two layers helps reduce noise.

Would you happen to have a few pics or a description that you could like me to?

Tom540

Fri Feb 13 2009, 05:16PM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
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GeordieBoy wrote ...

If you want to use double sided copper clad board, but don't need to route seperate nets differently on each layer, then just copy the same power traces on top and bottom to reduce DC resistance. Ground planes are useful for fast digital, RF and analogue applications, but can actually cause problems in power electronics applications. You certainly dont want a groundplane underneath the mid-point nodes of bridge legs. Any additional capacitance to ground here is detrimental to efficient operation of the H-bridge and makes noise problems worse!

A more effective use of the two layers is to make the top layer predominently DC bus positive, and the bottom layer predominently DC bus negative. Then you can use large areas to carry the supply currents and the capacitance between the two layers helps reduce noise.

-Richie,

This is exactly what I do on my bridge layouts. Top is mostly positive on the upper half of board bottom is mostly negative on lower half and the mid point outputs from the bridge are on both layers.

Tribologist

Sat Feb 14 2009, 05:00AM

Registered Member #1879 Joined: Mon Dec 22 2008, 04:11AM
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Posts: 40

Matt,

Ham radio guys have refined the science of building RF stuff over the years. There are a few ways we do it. Either route out between traces like shown here (my mini brute half bridge) or use Manhattan construction (cutting islands of PCB that you bond to the groundplane.)

is a lengthy article but cover it well.

Some great images can be seen here:

I like surface mount much better than any hole mounted methods since it is so easy to repace components, You don't need to use SMT components to do surface mounting. I built the controller for the minubrute on a vector board and I allready regretted it. Only reason was that I did not have any old AT pc boards left for making 0.1" pads for the IC's

I would allways keep the bottom a ground plane, that makes things behave more reliable, if I need more current capacity I add copper busswire to the top. The sheet I sent you is 2oz copper so it won't blister that easily.

Good luck with it.

Ulf

Arcstarter

Sun Feb 15 2009, 07:17PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Thanks for the links, i shall look over them.

But i am not making my driver on the copper, i already have a board for that. For the bridge it would only take a few traces per device. I still only need to know how exactly to use the bottom layer of copper. If used as a ground plane, you would obviously just attach all of the pins that require negative voltage on the bottom, and hook that to the negative of the power supply. Right..?

And Tom, do you have some pics of your bridge boards?

Thanks guys.

Why do the period bar and comma have to be right beside each other?

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