Ha! a wave soldering machine can be had for a song. I've got one made out of an electric skillet. HERES HOW THEY DO high volume cheap production over in China. It's likely your clock radio, toaster, and Tamaguchi pet are all made this way. Heat a big bucket of bulk solder, deep enough to not bottom out on component leads and wide enough to carry your circuit board. Stuff all the components in the proper holes. Pick up the board by the edges with a pair of wood(or more likely bamboo) tongs and dunk it solder side down into a tank of flux. Squeegee off the dross on the top of the molten solder with a metal spackling knife, then carefully dunk the sodler side of the board into the molted solder, just deep enough that the bottom of the board gets wet, but the top of the board stays dry. Hold for about 2 seconds, then remove quickly. Hold time and dunking depth are kind of critical, but not beyond the capabilities of a human hand. You can snip off the component ends, but they are mostly cut off in a saw fixture. Clean by dunking in a bucket of flux solvent and fish them out with a big spoon. I'm serious, I've toured the plants, and this is how the high volume low cost suppliers wave solder through-hole components. If you really need to do a short production run, and can't afford to have it made outside, this is the way to go. Even in a production palnt the whole setup probably cost them $100. With a few boards practice, the quality obtainable with this method is admirable, probably better than you'd do your self after the 1000th LED. -- Lawrence ----- Original Message ----- From: "Dale Botkin" To: Sent: Thursday, December 27, 2001 3:09 PM Subject: Re: [EE]: big led display > On Fri, 28 Dec 2001, Jinx wrote: > > > > Another option would be a colored plasic sheet with 7 segments > > > masked off, lit by brake lamps under PIC control with MOSFET > > > drivers. No moving parts, which I like better > > > > Filament bulbs ? Not fussy about those unless you run them under- > > voltage to extend lifetime. "grain of wheat" neons perhaps behind > > a diffuser > > For one that big I'd be more tempted to use bigger bulbs. Run 'em off a > 12V source... I only lose bulbs in my car every few years, and they run > on 13V+ and get a lot of abuse. Anything much smaller I'd be concerned > about the brightness in direct sunlight. > > > What I really objected to with LEDs was all that soldering. It took > > me the best part of half a day to solder up a 7 x 64 and I reckon > > you'd be looking at 30 hours (at what cost ?) to make a large > > 7-seg display. Imagine the tedium - LED after LED after LED.... > > Oh, yeah. It would be *almost* enough to make you wish for a wave > soldering machine. I say "almost" because I've seen what is involved > in owning one, was tempted a few years back. I could have had one fo next > to nothing, complete with 800# of solder -- still in the machine, of > course!! No thanks... > > Dale > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu