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PIC Project 16f887 - Binary Clock

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andyf:
Ade, I've made plenty of PCBs on UV sensitive board by drawing up the circuit in MS Paint, then printing out on to transparent film. It takes a bit of experimentation to find how many pixels there are to the inch, and you have to remember to place the film on the board the right way up to get the view from the copper side rather than the component side. Indeed, some say that plain thin white printer paper lets enough light through. In either case it's better to have the printed side next to the copper, to avoid light leakage and blurry edges. I use a wooden box containing a 12" UV fluorescent tube from Maplins, with a tight-fitting wooden lid to keep the UV away from my eyes. The box is lined with crumpled kitchen foil as a crude reflector/diffuser.

But for simple boards, I just use plain (non-UV) PCB painted with nail varnish as an etch resist - it dries quickly, and mistakes can easily be rectified by carefully chipping them away. Nail varnish can be a bit embarrassing to buy, though.

Andy

AdeV:
Nooo, stop it!


Must resist:  :proj:

raynerd:
AndyF - did you get your tubes from Maplin in store or maplin online -only I was looking for tubes and couldn`t find an instore supplier, only on line. Then I got drawn into the LED idea and decided to go with that. Thanks for the info Andyf, it was an interesting read. What do you use for the final etch - hydrochloric acid or ferric chloride?

Chris

Fred Bloggs:
Chris

Quote "What do you use for the final etch - hydrochloric acid or ferric chloride?" Most people do small scale board etching with Ferric chloride , I would have thought that the Hydrochloric acid would have to be very concentrated to etch the boards in a resonable time. Suggest that you use one of the small fish tank heaters to warm the Ferric Chloride up whilst it is etching and gentle aggitate, works alot quicker! You can resuse it quite a few times before its scrap, just be very careful how you dispose of it.

I have got several books (including the Babini series, the ones that maplins sell) on 555 timer circuits, I'll dig them out and post the proper titles and ISBN numbers on this thread if you interested?

Ps interesting stuff with regard to the PIC's, I brought a PIC development kit 10 years ago to do something with an old milling machine then met the SWMBO, kids etc and have yet to get it out of the box, arh well something for me to do next year!! when I finish the house etc etc.

Fred

andyf:
Hi Chris,

I got it in store, but that was years ago. Here's a pic of the unit - glass-topped box, with a foam-lined lid.




As to using nail varnish, here's a pic of a (commercial?) one for a 1980s design from Practical Wireless for a transverter to get a 28MHz transceiver to transmit and receive on the 50MHz amateur band:
http://www.uhf-satcom.com/misc/meon/m0eyt_meon_pcb_bottom.jpg .
When I got round to building it, supplies of the board Practically Wireless produced had run out, so I made my own (it's all boxed up, so no pic of it). Of course, that method would be no good for boards with lots of fine tracks running to ICs.

I have always used ferric chloride for etchant, with latex gloves - apart from its mordant quality, it stains badly, including fingers - looks like you smoke 100 a day.

Andy
Edit:
I don't think the uhf-satcom link works. Never mind - it wasn't terribly interesting.

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