The Magic Phone: Take Two

hadmagicphone

We’ve posted Part Two of the Magic Phone How-To over at Engadget. In this Installment, we show you the process behind creating the custom circuit that will live inside the rotary phone. This circuit is as small as possible by making it two-sided and by using surface mount components. Part One of the How-To covered number pad matrix decoding on just about any phone or number pad.

17 thoughts on “The Magic Phone: Take Two

  1. Guys, you complain when the hacks are too easy, now you complain when the hacks are too hard. Isn’t there room for variation? Isn’t that the mark of a good, well-aimed message?

    As a car guy I like to relate this to car magazines. I always want to see some easy projects, i.e. carb rebuilding, exhaust installs. I also want to see some highly technical articles, i.e DIY cam grinding, setting up ladder bar axles to hook up at the track, advanced fuel tuning. The easy articles open up the publication to newbies and re-inform veterans. Having at least one article above your head in each issue expands your horizons, it introduces you to things you didn’t previously think people were doing themselves.

    This hack is one of those, it’s unlikely that I’ll go out and execute this project but I like to see it posted becasue it appeals to the technical side of me.

    As to the comments I see about not having access to PCB-making equipment, the process being used is the process detailed here: http://www.fullnet.com/u/tomg/gooteepc.htm You can design and print your own circuit boards on a laser printer athen etch the design into blank PCBs. It takes basic CAD type skills along with a little chemistry similar to photo developing procedures.

  2. Derwin, I don’t mean to split hairs, but the pcb is just fiberglass with a layer of copper on it. If you were going to use silicon, you would need ion implanters, high vacuum diffusion ovens, laser scanners, wet and dry etch benches, and various other multi-million dollar tools.

    As for the pcb patterning method that billy posted, I can personally vouch for it. it works amazingly well, and is very inexpensive. the only problem that i’ve found with it is trying to make two-sided boards. the pattern transfers perfectly to the first side, and then the pattern will transfer perfectly to the second side as well. the problem is that when you iron the second side on, you melt the toner on side one and totally screw it up.

    i experimented with trying to pattern both sides at once by using an iron on a stove, and ended up cooking the copper right off the board. it was a simple mistake of having the oven on too high, but it was costly… burning copper/fiberglass smells like cat piss… i later measured the temperature of my iron and stove with my multimeter, and the iron was around 400f if i remember correctly, but my thermocouple melted and disappeared at around 900 (and climbing) on the stove…

    now that i’m completely rambling, i think i’ll shut up.

  3. “this how-to is so easy, i can’t wait to get into my basement and dip silicon into that readily-available homemade circuit printing laboratory.”

    I bit the bullet and built such a thing. I started doing the simple toner-transfer method, then etching the board in a tupperware over the bathroom radiator. I couldn’t buy plain copper clad boards at the time, so I bought photo boards and removed the mask with acetone. The transfer never came out right (though workable) & I sweat to death over the radiator.

    I finally got my act together – for 10 euro (yes, only ten!) I put together a photo PCB home lab. I bought a used sun lamp (‘cancer in your home machine’), tall etching tank (tall plastic container), and aquarium pump/air stone. The whole lot goes in a pot of water on the stove for heat (an aquarium heater is a future improvement).

    It works great. I’ve been using the same batch of etchant (a persulfate salt) for two months now, making 2-3 boards a week.

    Notes:
    1. I use inkjet transparencies to make my photo positive. I MUST use two layers or the traces burn right off the board. I’m going to experiment with colors, and the so-called ‘high quality black’ when I get my color ink cartridge refilled.

    2. I needed some sort of box to squish the PCB & photo masks together. Lacking a nice plexiglass clamp box, I used a CD jewel case (black part removed) with a few paper towels in the bottom.

  4. schnake: i think it’s just engadget’s nightly maintenance time, not a real had-effect *smile*

    billy et al: thanks for sticking up for my geek pr0n post, eliot convinced me to mix up the how-to’s with both simple and tough projects.

  5. I have no idea what you are doing but it looks like fun. I really liked billytheimapler’s comments. How absolutly true he is. Even the most esoteric subjects can be interesting. I find myself following web pages, howto books, and magazines articles in topics that I have no expertise in but still it is interesting. The wealth of knowledge out here is astounding. A circuit board looks like a Picasso to me.

    Gary

  6. I have no idea what you are doing but it looks like fun. I really liked billytheimapler’s comments. How absolutly true he is. Even the most esoteric subjects can be interesting. I find myself following web pages, howto books, and magazines articles in topics that I have no expertise in but still it is interesting. The wealth of knowledge out here is astounding. A circuit board looks like a Picasso to me.

    Gary

  7. hear hear, another vote for having a nice range of difficulties, from dirt simple hacks, to basement tunneling electron microscopes (there are a couple out there!). Making your own PCBs isn’t that hard (I’ve done it also) but even if it were I think it wouldn’t be offtopic for a site like h-a-d.

  8. When they say its too hard, this comes out of frustration :-)

    Pitty them *hrhr*

    (Its more… complexity is really nice, because if its simple as LEGO, it prefer that. But its annoying when you have to spend hours wiring stupid stuff which seems )

    Making PCBs: Maybe there are tricks, on how to make it without too many apparatus or money.

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