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Messages - davent

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General Questions / Re: PCB etching adventure...
« on: February 18, 2013, 12:59:47 PM »
Little known Mayan Pedal Deity.

edit;spelling... blah

General Questions / Re: PCB etching adventure...
« on: February 18, 2013, 11:37:55 AM »
I've also hear the method you are trying is superior, but the cost of a lamp an photoresist boards kept me away.

PnP blue works really well.  And it's pretty easy.  You just need a laser printer.  I picked up a new HP P1005 for like 90$ just for this purpose.

All you need as far as a lamp is any old flourescent tube. I screwed a piece of plexiglas to the joists above my workbench where the lights are recessed between the joists and just pop the exposure package up there when i need to do boards. Half an hour from printing out a transparency to having the etched board in hand.  Before the joist trick i would stack up phonebooks, fat electronic catalogues etc. on the kitchen counter until i could get the exposure pkg within an inch of the tube under the kitchen cupboards.

No need for a safe light (red) the board isn't sensitive enough that the ambient light of the room will wreck the board before you expose it proper. Under flourescent lamps it takes ~10 min. exposure. Just work in an unlit room with abit of light from a cracked door. I've loaded up boards put them under the lights only to realize my transparency is wrong side up, turn the lights out correct the package, back under the lights and the boards tumed out as good as ever.

Dollar store plastic tubs, as small as will still allow the board to fit in flat against the bottom. I've read of people using heavy duty ziplock bags.

For an exposure pack i use an Ikea frameless picture holder, a clip on each side holds the glass to the backing board, takes seconds to load the art and board in and get it up under the lights. Again dollar store might have something.

+1 for muriatic acid and hydrogen peroxide.
Developer i use is MG Chemicals 1:10 with water, takes about a minute to develope when fresh but i'll use the same batch over and over until its almost black.

To figure out your exposure time take a small strip of board and load it in you frame with a pcb transparency, put it under your light for say seven minutes then cover about  a 1/2 inch with a piece of opaque cardboard, wait two minutes slide the cardboard over to cover another 1/2"... every two minute cover a bit more of board with cardboard until theres no more board left exposed.

Develop the board and you'll have strips that were exposed for from 7min to say 15min in 2 minute intervals. One of those strips will show the minimum time (what you are aiming for) that you need to expose the boards with your lighting setup for a perfectly exposed board. (and there really is a great deal of latitude as the boards aren't very sensitive... slow in old photo parlance.) You only need to do this once unless you change your lighting setup, all the different brands of boards i've tried end up around 9-10 minutes with the lights above the workbench.

Take care,

General Questions / Re: inkjet graphic transfer
« on: February 17, 2013, 06:20:08 PM »
Hi Hector,
I do as much as possible with waterbased paints  and stuff as the other solvents make me sick with much exposure so haven't tried this with regular sparycan  paints. As long as the acrylic medium will stick to the spraycan paint, should be no problems with this technique. The issue i've had in the past is that some of the clear spraycan lacquers i used to use haven't worked well over acrylic paints. They go on fine and look great but after a period time, months, the clear ends up all checked and cracked, not an issue in itself but pretty dissappointing to see after all the time that went into getting a nice finish.

I haven't tried it but lots of people get great looking, very protective clear for their pedals using Envirotex which is a pourable epoxy product.

Information in the link here is what spurred me on to see if there was a less toxic way to do transfers. Here they use Damar varnish as the medium and they are using it to transfer toner as well as inkjet images/art to bare medal.

Open Discussion / Re: tube amp power scaling
« on: February 17, 2013, 05:58:15 PM »
You should check out Dana Hall's VVR circuit, has a few differnt ones available for either fixed or cathode bias, not sure how big an amp they'll accomodate.

As well check out the Power Scaling kits available at London Power.


General Questions / Re: inkjet graphic transfer
« on: February 16, 2013, 10:56:56 PM »

 Can you apply the acrylic medium on bare enclosures or painted enclosures? And if you could, does it need any special preparation?
Also, the acrylic medium the guy in the video uses, is matte. I guess gloss medium exists too. Is it hard enough not to peel off with use and not to need any clearcoat? (supposing you can spray clearcoat on the acrylic medium)

Sorry for all the questions, but I'm really interested in learning to use that! ;)


Hi Hector, no problem.
 Haven't tried a bare enclosure but doubt it would work very well as it's tough to get anything to really bond well with the enclosure outside of powdercoat. I use self-etching primer as the first layer then progress through a couple others before laying in acrylic colours. After the colours i'll go with the medium to do the toner transfer. The GAC200 medium i use is gloss but because it dries in contact with paper when you remove the dried paper the medium left has a slightly textured surface so even though it was gloss medium it will show as a matt.

The acrylic paints and mediums won't stand up to much abuse so they do have to be clearcoated. If you use a great deal of water in removing the paper,  the medium will absorb a bit of water and turn milky looking again but you just let it re-dry  and it clears up fine. I use waterbased lacquer for clearcoating but the pictured Bazz Fuss was clearcoated with Varathane which is a waterbased brushing varnish sold for finishing wood projects, works well but it never totally loses the milky veil.  Except for the self-etching primer, spraycan,  i brush, splatter or airbrush all the other finishes/paints.

This is the video I'm talking about that's on youtube. Didn't know if i could put links to youtube vids but everyone else is so i must be able to.... :P

Hi Dan,
All this is pure speculation on my part, have no experience with this process so...

Don't think it would work, as is, going onto an enclosure. The ink from the waxed paper (i'm thinking that it's actually a plastic coating on the paper,,, like freezer paper) needs something to bite into for it to move off of that paper. An enclosure would need a coating on it that would absorb the ink pulling it from the transfer surface. Golden make a couple mediums that might give you the necessary bite, Acrylic Grounds for Pastel i've used to allow using pencil crayons and charcoal over top of slick acrylic painting, this just is a grittier surface that catched the dust deposited from the pencil or whatever. Then there's Digital Grounds for Non-Porous Surfaces, i've read that it's been used to coat aluminum foil and put through a printer and given good results. Maybe coating the enclosure with that medium would  give enough of something for the ink to grab onto and transfer to an enclosure.  Just thinking out loud.

Info on the Digital Grounds:

Other companies no doubt have similar products but Golden is the suff stocked most widely around here.

Take care

Open Discussion / Re: soldering on etched boards
« on: February 16, 2013, 07:55:39 PM »
I've found with liquid tin that if you leave it for days you're really no better off in ease of soldering then if you've left the copper traces bare. I never finish a pcb in one go, could be days between sessions so the traces do oxidize and become diifficult to solder and then because the boards partially completed it's a pain to try to restore the unsoldered pads to an unoxidized state again. Best for me is polish the copper traces and spray the board with some kind of lacquer, waterbased, solvent based, Testors candy coloured transparent, whatever lacquer i have on hand and that will prevent any oxidation. Touch a hot soldering iron to the pad in the process of soldering and the lacquer vaporizes, solder flows. Done!


Tech Help - Projects Page / Re: Question With LED in Pos Ground
« on: February 16, 2013, 07:29:02 PM »
Since it's a positive ground circuit the red lead from your battery snap goes to the ground pad of the pcb and the black lead from the battery snap goes to the -9v pad of the pcb. (Page 4 of the pdf.)

General Questions / Re: inkjet graphic transfer
« on: February 15, 2013, 09:32:01 AM »
Hi Hector, thanks!

Acrylic medium is just the clear substance that pigments are added to, to give us acrylic paint. Available in various viscosities from thick gels to almost water thin. You can in fact just use acrylic paint to glue down your toner art in this method of transfering if the paint is going work with the colour of your enclosure. I work with a clear, fairly watery medium called GAC200 made by Golden, a company that produces a huge range of acrylic paints and mediums. No idea whether that brand is available in Greece  but there are lots of different brands out there. And... no heat what-so-ever is needed to do the transfers.

This video does a great job of explaining the technique.

General Questions / Re: inkjet graphic transfer
« on: February 14, 2013, 07:05:07 PM »
I've been doing toner transfers rather then waterslide decals for the last year or so. Haven't tried inkjet transfers but came home from the library today with the book "The Collage Workbook' and it breifly  describes a method that uses transparencies to do inkjet transfers.

Print the 'art' to transparency film.
Coat your receiving surface (enclosure?) with gloss acrylic medium, lay your art into the wet medium, smooth with a bone folder or back of a spoon, wait a few seconds then lift a corner of the transparecy to set if transfer is taking place. I suppose if it hasn't happened yet you lay it back down, smooth, wait and peek again.

Going to take some trial and error to get the knack.

For toner transfer you just print to regular paper then use an acrylic medium to stick your art to the enclosure, let it dry then wet and rub the paper away with your fingers. Takes a few dry/wet/rub cycles to get all the paper off but with a bit of patience it goes.

First attempt, just kept throwing new printouts onto the enclosure to see what was possible with the technique. The 'typewriter' font i was using is a very distressed version and the transfer is a true representation.


Compressor detail

Open Discussion / Re: wedge style boxes
« on: February 01, 2013, 05:18:56 PM »
A few people at diystompboxes, have shown wedges made by cutting down regular cast rectangular boxes.


Tech Help - Projects Page / Re: Power supply advice
« on: January 31, 2013, 04:20:21 PM »
Required reading from GEOFEX.

I would go with multiple small transformers as opposed to one transformer with multiple secondaries. Small, dual secondary transformers should be easy to find, the ones i have have a dual 120v primaries  so are good for N.A. and Europe.

Open Discussion / Re: How to tell if an IC is operable
« on: January 20, 2013, 06:10:18 PM »
Haven't tried this but worth a look.


General Questions / Re: Custom Drilling?
« on: January 19, 2013, 01:07:09 PM »
Another option to check out, (haven't tried).


Open Discussion / Re: What DMM do you use ?
« on: January 16, 2013, 01:13:30 PM »
Fluke 8050A, got very lucky, $30 on ebay a few years ago. Plus a few cheapies for convenience and when needing multiple similtaneous readings or measurements not covered by the Fluke.

Open Discussion / Re: Momentary / Latching modifications.
« on: January 15, 2013, 07:49:12 PM »
Anatomy and rehabbing of stompswitch video and how to convert a switch. Take it apart, reshape the switch rockers, reassemble and you're good to go. Need to watch through the whole video to see the latching rockers early on and the momentary rockers at about 8min. Haven't tried this but if Mark says it's so... it's so.


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