Hero999 Posted September 10, 2009 Report Share Posted September 10, 2009 Attached are some pictures of the PCB for a noise generator I'm currently building.I used the toner transfer process with magazine paper. For the silk screen I covered the toner with a thin conformal coating to stop it from being scratched off.It isn't perfect but it's good enough for me - the traces all etched perfectly which is the most important thing.Although I've experimented with printing a silk screen before, this is the first time I've done it for real. As you can see it isn't perfect. The toner all stuck perfectly, but some bits came off when I cleaned it so I filled in the gaps with a permanent marker which ran when I sprayed on the conformal coating. The alignment also isn't perfect and there's some slight bleeding which I think could be caused by the temperature setting being too high. I've learnt a couple s few things from this. Next time I'm going to be more careful cleaning it, I'll a pencil to do touch ups and iron using a slightly lower temperature setting. Quote Link to comment Share on other sites More sharing options...
gogo2520 Posted September 11, 2009 Report Share Posted September 11, 2009 Nice looking board Hero999 . You used conformal coating? I have a few ideas for my next board, Have you ever tried this stuff http://www.web-tronics.com/torefowpwh.html I also have some small silk screen like stuff in small sheets that can be photo exposed, haven't tried that yet, think I am saving it for a real good board that I would want to reproduce in numbers. http://www.photoezsilkscreen.com/howto-create.htm anyways, your boards look good Thanks for sharing gogo Quote Link to comment Share on other sites More sharing options...
Hero999 Posted September 11, 2009 Author Report Share Posted September 11, 2009 Yes, I've seen many proprietary silk screen products but I've never used them. They look nice but they're also more expensive than simple toner transfer. I think black is fine for a silk screen, it does the job and I've seen professional PCBs with a black silk screen.Here's a link to the lacquer I use:http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=569-290&x=0&y=0My only concern is that it might not be resistant to isopropanol or acetone which I use to remove the solder flux from the board. I might have to switch to a solder with water soluble flux.Here's a PDF of the schematic and PCB layout. I noticed an error in the PCB after etching the board, I forgot to connect the op-amp's 0V pin, the error has been corrected on the attached file.Here's a link to where I borrowed the design for the low pass filter fromhttp://sound.westhost.com/project11.htmNoise_generator.pdf Quote Link to comment Share on other sites More sharing options...
Hero999 Posted September 12, 2009 Author Report Share Posted September 12, 2009 I've assembled the PCB now.I haven't tested it yet though. Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 13, 2009 Report Share Posted September 13, 2009 I made my pink noise generator with a National Semi MM5837 psuedo-random digital noise generator IC (now it is obsolete). I used a few RC networks to convert the white noise into pink noise then I tweaked the values for it to match the output of a very expensive professional noise generator. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.