Token Machine (Etch your own circuit board!)

[fatfingers]

For about a year now I've been in the process of trying to get a token machine built.  Well, I still have nothing (much) to show for it, but I did buy a coin hopper off of ebay at one point -- and it works very well.  Some friends and I designed a circuit to drive the hopper when a button is pressed (I'm not going to use money or a bill reader for this).  The plan was to etch my own circuit board and solder all the connections on the board and then build a case around all of that and then, bingo, token machine.

Well, after struggling for many months, I -finally- got my PCB etched to my satisfaction.  It's not perfect, but all the traces are fine.  I have attached a picture of the board.  The next step is to do the soldering, which I'm sure will be really painful because some of those traces are awfully close together and I really have never soldered before (except once WAYYYYYY back in 8th grade electronics class and a couple practice joints a few months back).

In any case, I thought I'd mention it just 'cuz I'm so proud of myself.   

Oh, BTW, the final thing that made me successful in this etch was the discovery of the site PCB Fab In A Box.  It seems their system is so simple, and other methods that appeared to be simple on you-tube just did not work out for me.

[severdhed]

very cool....keep us posted.  i would love  to have a token dispenser, and quite a few time started designing my own, but never came up with anything as remotely as cool as you did.



lets us know how it works out

[TheShanMan]

Definitely keep us updated on the progress. This is very cool. Gonna have to check out that link you gave.

[thecheat]

I had to etch a board for something a while ago and I used a similar method.


Printing a flipped image from a laser printer, then ironing it on to the copper, then washing the paper away to leave the toner as a mask. It worked well enough to etch correctly but it was pretty ugly.

[fatfingers]

Yeah, that's what I was trying as well.  I could never get the paper to wash away enough for a good etch though.  The toner transfer paper from the site I listed is the bomb.

[MonMotha]

You can buy UV sensitive copper clad.  What you do is print your layout on a transparency using a high-res laser printer, affix it over the copper clad, then expose to UV (i.e. leave it out in the sun for a while).  The etchant will not etch except where exposed to UV (or vice versa - I can't remember).  This supposedly works well enough to hit about 12/12 or even 10/10 line/space.  Some people claim 8/10 or even 8/8 with lots of care.

If you want cheap professionally made boards (with plated holes!), I like the Advanced Circuits "Bare Bones" deal.  You can get reasonable size boards in 1-2 quantity for about $20-30 each, which is actually quite a deal.  If you do fine-pitch SMT and want a soldermask, they also have a $33/ea deal, but there's a minimum order of 4 (though you get a 5th free).  Excellent customer service, too.

[SavannahLion]

Oh, BTW, the final thing that made me successful in this etch was the discovery of the site PCB Fab In A Box.  It seems their system is so simple, and other methods that appeared to be simple on you-tube just did not work out for me.

Isn't that exactly that this guy did? http://www.fullnet.com/~tomg/gooteepc.htm

BTW, did you use FeCL or did you use Copper Chloride? The FeCL is so damn expensive and hardly anyone around here carries it.

[fatfingers]

Yes, he did essentially the same thing...I just could not find any paper that would remove easily enough.  It may have been the temperature and/or pressure with my iron that wasn't quite right...who knows.  All I know is the first time I tried the fab in the box kit, I got a perfect etch.  So, that's the one for me, obviously.  YMMV.

I used HCl + H2O2, which I believe is the Copper Chloride you're talking about (probably actually called cuprous chloride).  I also have some Ferric Chloride here, but I never tried it.  Normally I would offer to send it to you if you wanted it, but I have this feeling I can't send it legally or something.  Radio Shack did not carry it for quite some time, but they do seem to have it now.  I have even seen it in their stores now.

[fatfingers]

You can buy UV sensitive copper clad.  What you do is print your layout on a transparency using a high-res laser printer, affix it over the copper clad, then expose to UV (i.e. leave it out in the sun for a while).  The etchant will not etch except where exposed to UV (or vice versa - I can't remember).  This supposedly works well enough to hit about 12/12 or even 10/10 line/space.  Some people claim 8/10 or even 8/8 with lots of care.

If you want cheap professionally made boards (with plated holes!), I like the Advanced Circuits "Bare Bones" deal.  You can get reasonable size boards in 1-2 quantity for about $20-30 each, which is actually quite a deal.  If you do fine-pitch SMT and want a soldermask, they also have a $33/ea deal, but there's a minimum order of 4 (though you get a 5th free).  Excellent customer service, too.

Yeah, those board prices seem very decent.  All in all I ended up spending more money doing this by myself than if I would have paid to have it done.  However, my goal was not to do it cheaply, but to do it myself, just for the 'geek factor'.  I'm pretty proud I've been able to do it.  I even have traces as small as 0.008" on my board!  Oh, and now that I know how to do it, I'd be able to do it cheaper than the professional boards.  Obviously not as nice looking, but they work.