PCB layout for all N-type ZEN (aka Lidstrom ZENi)

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I have finished a preliminary PCB layout and would like to run it past a few people more experienced at this sort of thing than I. I have Used the Lidstrom ZENi CCS circuit with the original ZEN gain stage (plus some capacitor bypassing). I would appreciate any advice/constructive criticism of the design as this is my first attempt at this sort of thing and I may have made some glaring errors or just gone about things the wrong/long way.

I do not have a web site so I guess I'll email the layout to anyone who is interested in having a look. I drew the layout in Autocad R14 but I can convert it to a jpeg image if required.


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You can email it to me. vdi_nenna@hotmail.com

If you can convert it to jpeg, it will be easier for me to open and download.

The circuit is simple and parts placement isn't ultra critical. Make sure you use wide traces for high current parts of the circuit, like near the rails and CCS. If I were to build a board for this amp, I would make it 2 individual channels. It's much more flexable to manuver in a chassis. I can see why it was originally designed as 2 on one board: makes it easier to parrallel in the future and for the simple fact that it's a small circuit.

How are you going to transfer the image to copper??
PCB Manufacture ???

As far as I know there are 2 ways for the hobbyist to make PCB's

1) Starting with a blank copper faced sheet iron a print of the image from a laser printer on to the copper and then place in an ammonium persulphate solution to remove excess copper.

2) buy a light sensitive kit and use this to expose the board under UV light source before etching (not sure of the solution).

The 1st method I read in a local magazine (Australian) called silicone chip.

I haven't tried either of these methods, as I said previously this is my first attempt at this sort of thing.

Anybody got any other ideas or tips to save me some time/money with this. Before I do this I want to make sure the design is correct, hence my starting this post.

the easiest way to do it (if you dont got any equipment at all) is to buy a glassfiber board with a 100micron coppar layer and photo resist (availible in every electronic component store) print out atleast 2-3 identical layouts on transparent paper and glue them on top of each other this must be really really black atleast if you are not certain of proper "light" time

then you can place the copper board with the original on top of it (with a glass plate to hold it on place)let it lie in the sun for about 5-10minutes (not so critical if the original is really black)

then you remove the excessive photo resist with NAOH (caustic soda) the pattern should now be clearly vissible.

then you use a mix of HCL,H20, H2O2 in equal quantiteas

but be really carfull with the chemicals be outside or under a kitchen fan !!


The Kitchen fan is a real bad ideer. Unless your want to have a rusty fan. The free HCL gas vill attack any iron or metal in that room, so if you want too use HCL and H2O2, Stay outdoor and please use gloves and safety glasses.
A better ideer is to use Ferri Chloride or Ammonium persulphate.
Ferri chloride can be used at room temperature but makes nasty stains and is not quit as detailed.
Ammonium persulphate must be heated to 45C and is more detailed than Ferri chloride, But as long as its PCB's for amplifiers both will do the job.
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If you decide you want to use the transparent transfer method, be sure you reverse the image to the transfer film. it should be easy, because I saw that you sent it in .BMP. Use Paint to flip th image. Use a laser printer or copier and make multiple copies of the PCB traces. Iron them on top of each other. It will give you a more solid image on the copper before etching.

Haven't had a chance to check the artwork yet, as I was camping up in the mountains, communing with owls and such.
However, here's my take on doing a circuit board:
1) I am loath to waste things if I can avoid it. (My Scottish blood coming to the surface.) I buy the big 18x18" blank boards as it's cheaper per square inch, and I know I'll use it sooner or later. I come up with a layout, then cut a piece of board to that exact size. For this reason, I don't use the optical boards, as I've yet to figure out how to cut a board in the dark. I believe I've seen the photo-resist stuff as a paint, but for the life of me, can't remember where. If someone knows where to get it, pipe up. I'm also going to want to know how to get an even coat.
2) I use the print-it-on-a-laser paper. Resolution is, in theory, good. In practice, it's compromised somewhat. Incidentally, I do *not* recommend the use of an iron. Every time I've tried that, I've ended up with some traces that were smeared (too much heat/pressure), or didn't transfer at all (too little). Put bluntly, the people who make the stuff lie; it ain't easy. But I've developed a system that works pretty well. First, print the image on the paper, then run the same piece of paper back through again for a second printing. Note that this takes a printer that registers the image pretty accurately. Clean the board with 0000 steel wool. Align the image on the paper with the board and tape it in place with masking tape so that it won't slip around. Now, here's the part that cost me a lot of agonizing: The heat & pressure. I preheat the oven to 400 degrees F. Preheating in the oven are several gray bricks (the same as cinder blocks, but brick-sized, with no holes). I have ground these against one another until I got a good face-to-face contact. Even pressure is crucial, and is one reason the iron method fails. By trial and error, I have discovered that something on the order of 1 pound per square inch of circuit board is optimal. There is some leeway in this, but don't go too far to one side or the other. The gray bricks are about 4 1/2 pounds apiece. I place one underneath, and ever how many above that I need to come close to the 1 psi figure. The for-weight-only bricks need not have flat faces, they're just along for the ride. I use a paper towel, folded, on each side to cusion the board from the surfaces of the bricks and to smooth out the pressure. When all is ready, turn off the oven, place the circuit board on the bottom brick, then add bricks on top for sufficient pressure. Bake for 3 min. The heat stored in the bricks and in the oven is enough to do the job. The paper will not burn, although it might turn a toasty golden brown. When done, pull the bricks off the top, toss the board on the kitchen counter and put something heavy and flat on it while it cools to keep the paper from crinkling. I use a wooden cutting board. Once it's cool, pull the masking tape off carefully, as you don't want to rip the paper away prematurely. You're then free to soak in water. I've seen a paper that is supposed to peel away without water. I haven't tried it, and so have no opinion. The soaking in water isn't the hard part, anyway, it's getting the right heat and pressure that's the booger. Inspect the board carefully to make sure that you got a good transfer. Patch any bad spots with an etch resist pen or Sharpie, but lay it on thick. Use an Exacto knife to scrape away any excess.
When written out like this, it appears more complicated than it is in use. That's on account of the fact that I'm a wordy critter.
Oh, the image should be a component-side view, positive.
I'll try to get around to looking at the artwork tomorrow sometime.

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