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Tech Chat Manufacturing your own PCB

 
Till Eulenspiegel
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I doubt if anyone would go to trouble of making a complex printed circuit board by using the old method of laying on pieces of crepe material on the grid pattern. sheet.   Made sometime in the late eighties or early nineties a 405 sync and blanking board for a 405 line converter project. No CAD assistance.

405 BLkg Sync

Till Eulenspiegel.

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Topic starter Posted : 27/11/2021 12:08 pm
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Cathovisor
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@till 

I remember my colleagues at work doing just that though - and a step below that was the "Dalo" pen. Later on, when CAD packages and UV-sensitised boards became available a couple of friends made their boards using laser-printable OHP film, being careful not to accidentally produce a "Doppelganger*" and passing the film twice through the printer to get sufficient density.

 

*this was where you accidentally produced a mirror-image of the track layout.

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Posted : 27/11/2021 12:33 pm
helloekco
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Posted by: @cathovisor

Later on, when CAD packages and UV-sensitised boards became available a couple of friends made their boards using laser-printable OHP film, being careful not to accidentally produce a "Doppelganger*" and passing the film twice through the printer to get sufficient density.

This is what we did on my GCSE electronics course in the early 90s, except that we used a plotter to create the transparency.

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Posted : 27/11/2021 2:33 pm
Till Eulenspiegel
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 I understand the BBC digital 625 to 405 line converter PCB artwork was made in a similar manner.  

Till Eulenspiegel.

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Topic starter Posted : 27/11/2021 3:37 pm
Cathovisor
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@till It's a pity D&ED no longer exist to ask them, unless there's an issue of Eng Inf that mentions it: when they were the only show in town you could understand the BBC making all its own equipment. I think one of the last studios to use BBC Coded Equipment was TC5 in its last analogue refurbishment in 1986. It also had a digital video decoder and a digital vision mixer (called a "combiner") for the graphics area.

It was certainly using the BBC-designed analogue video DAs right up to its closure in 2011.

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Posted : 27/11/2021 5:23 pm
WayneD
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The only pic I have of my prototype attempts from 2013. I used a CFL bulb as a UV exposure and it worked very well. I drew this in MS Paint and printed it onto an overhead projector transparency. The big gap in the bottom left was eventually used for something else.

FB IMG 1638031923486

 

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Posted : 27/11/2021 6:05 pm
Jayceebee
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Many years ago I constructed the PW mag Tele-Tennis, lots of TTL ICs on several boards. They were drawn by hand with a Dalo pen and although not pretty they worked. later I tried those rub on pads and tracks but were a bit of a pain.

I'm currently working on a replacement field board for Chris's 4000 using the toner transfer method. I've not attempted this before but seems to be possible to produce good results. Unfortunately I don't have a laser printer but a work colleague is helping me out with this. 

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Posted : 27/11/2021 9:04 pm
Jayceebee
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Posted by: @cathovisor

..... being careful not to accidentally produce a "Doppelganger*" .

Something woke me at 3am the other day and that exact thing came to mind and that I needed to mirror the design 👍 

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Posted : 27/11/2021 9:26 pm
WayneD
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Posted by: @jayceebee

Many years ago I constructed the PW mag Tele-Tennis, lots of TTL ICs on several boards. They were drawn by hand with a Dalo pen and although not pretty they worked. later I tried those rub on pads and tracks but were a bit of a pain.

*shudders* oh I remember the rub on pads and tracks! Took about 10 times as long to draw something out. I preferred the stencils but even then I'd just use it for the pads and still draw in the tracks by hand.

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Posted : 27/11/2021 9:31 pm
WayneD
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Posted by: @jayceebee

I'm currently working on a replacement field board for Chris's 4000 using the toner transfer method. I've not attempted this before but seems to be possible to produce good results. Unfortunately I don't have a laser printer but a work colleague is helping me out with this. 

My Father in-law (ex-technology teacher) has had really good results with this. He doesn't even bother removing the toner from the copper afterwards apart from the actual solder pads. He's found takeaway menus seem to work best to print the toner onto first before transferring it to the copper clad board.

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Posted : 27/11/2021 9:38 pm
Jayceebee
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@wayned I’ve seen one technique using that involves magazine paper and nail varnish remover, no heat involved. It seems to give amazing results.

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Posted : 27/11/2021 10:25 pm