My PCB Design second time in 20yrs.

Discussion in 'The Projects Forum' started by Fenris, Jun 23, 2008.

  1. Fenris

    Thread Starter Active Member

    Oct 21, 2007
    288
    2
    hi all

    its been some time since i last posted in here. what with decorating and a change of OS (i forgot to save my favorites off) ive had a bit of time finding the forum again. Found you!!! well my last post involved the workings of darlington transistors i needed to drive a pair of filament bulbs in parallel. thanks to all for your advice. i am now at the stage where i have used press n peel to mark a pcb for etching. this is done and im going to be building the circuit proper over the next few days. its only the second time ive ever done my own PCB and what a difference having readily available materials like press n peel has made. theres still a bit of a knack to it. only 3 attempts to get a good masking. etching took 10 mins with ferric chloride in a tray which itself was sat in a tray that had hot water in it to warm the solution up and speed up the effect. All good fun and im pleased with the result. i just hope it all works once its built. i should mention that the sound to light is in addition to another part of the circuit that is a voice modulator...........voice mod........flashing lights.......you got it yet???? think pepper pots. any way i present a picture of the PCB for your viewing. you might notice the PCB's shown are marked differently so actually ive done my own board 3 times in 20yrs. the middle pic is the first of this pair and showed up some areas that needed moving and adjusting to suit wires that will carry the power and just make it less of a crowbar job soldering in and around the board.
     
  2. ShaunManners

    Active Member

    Feb 16, 2008
    72
    1
    Thats a useful tip about the tray of hot water... I hadn't thought of that. The last board I made took about 15 minutes in ferric chloride...

    Do you have any tips for using the press n peel? I found it fantastic apart from where some of the track was taken off when I peeled it back. I touched it up with permanent marker, but I was left with a pitted section of track :mad:

    Cheers
    Shaun
     
  3. Fenris

    Thread Starter Active Member

    Oct 21, 2007
    288
    2
    hi there

    glad that was useful to you. As for tips about the press n peel i have a few based on my limited use of it. make sure if you cut the PCB yourself use a fine hack saw and cut with the copper side up. deburr all the edges of the copper. remember to clean the board with a fine grade of steel wool then water and mild detergent, dry with a lint free cloth and don't touch the surface with your fingers again! try not to touch the print side of the press n peel either.

    1. The transfer should be at least 5mm all round oversize.
    2. The PCB must be bigger than the over sized transfer sheet.
    3. If you are printing your own then it is worth pulling the toner cartridge out and giving it a shake to distribute the contents evenly inside.
    4. Don't forget to heat the board first for about 30-45 seconds. As well as helping the adhesion it, possibly, helps prevent problems with expansion of the board smearing the pattern.
    5. Do not sweep or wiggle the iron. lift and place back down vertically moving across the PCB inch by inch remembering to apply plenty of pressure in total about 3 minutes is enough. do use a clean piece of paper between the iron and transfer medium and when heating the PCB prior to application. there is also a trick where you use a drill bit or wood dowel as a roller underneath and you slowly go back and forth. the theory being you will get a good bit of pressure between it and the iron. i havent tried it so there may be a bit of a knack to it. There are people who butcher laminators to use to apply the transfer but you have to do something fancy with the roller motor to slow it down (they are usually AC synchronous!!) one solution was to install a dc motor with the appropriate motor control. further to that they also change the thermostat sensor to increase the standard 120 degree temp to 275-325 degrees.

    The reason for going oversize with the transfer paper is it seems to help stop the edges 'scalloping' and in turn distorting the tracks, during heating, that may be near the edges. The board needs to be bigger so that there are no unsupported edges of the transfer as the difference in heat transfer between that which is on the copper clad board and that which isn't will also cause distortion of the sheet.

    As regards the toner cartridge. I mention this purely because i had to use my etch resist pen to patch some areas of the transfer as it was a bit patchy in areas. This i believe is down to uneven toner distribution leading to an uneven density which isn't apparent until you transfer the pattern to the PCB.

    you can see at the bottom edge of my board that the tracks are a bit ragged but it was passable and i did have to use an etch resist pen to patch some of the tracks especially the really thick area. i think that was down to uneven distribution of the toner (see note above) if you are printing your own (luxury!) then make sure your settings are for the highest density of print and do the toner shake! It is good stuff to use for prototyping but when it goes wrong its a pain in the behind. even with all the above you may find you still have to touch up the tracks but hopefully to a lesser degree. avoid large solid areas of print as they can be problematic if you need them then i have seen someone do a very fine mesh pattern in those areas which seems to help.i hope that help you out.
     
    Last edited: Jun 24, 2008
  4. Fenris

    Thread Starter Active Member

    Oct 21, 2007
    288
    2
    Hi all

    Well day by day i have gradually assembled the components on the PCB and attached all the wiring. First test was yesterday, mainly to see if the voice modulator worked, and initially all i had was the low level buzz that indicated that the 4066 and the 7555 were doing their job. However speaking into the mic delivered nothing!!!! A quick visual check was made which produced nothing obvious. So back to the PC pull up the PCB and the schematic. It took 2 minutes to pin point the problem :eek: A piece of track 6mm long had been missed out so the LM358 was lacking its ground connection to pin 4 :rolleyes:
    2 minutes with the iron and a piece of component lead i bridged the error and hey presto it works!!!!! The sound to light portion i cant test until a fellow dalek builder drops the light harness round. But i have already found a fault there.........there are 4 BC type transistors 1 PNP the remainder are NPN.......they are all round the wrong way!!!! So a quick burst of desoldering, rotating 180 degrees and a resolder are required first any how. Heres some pics of the finished, but, unboxed circuit.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I didn't get your "pepper pot" reference at first; we call them "pepper shakers" in the US ;)

    Nice job on the board :)

    A Dalek voice modulator and light flasher - fun project.

    [eta]
    Have a look at this fellow's page:
    http://home.comcast.net/~trabold/dalek.html

    He is well on his way to having a FLEET of Daleks! :eek:
     
    Last edited: Jun 28, 2008
  6. Fenris

    Thread Starter Active Member

    Oct 21, 2007
    288
    2
    cheers m8y

    yes ive seen that chaps dalek hes done a damn fine job. his original plan to use peddle power is inline with the original plan back in the 60's when they first appeared.

    regards

    Fenris
     
  7. Fenris

    Thread Starter Active Member

    Oct 21, 2007
    288
    2
    Hi all

    heres a few pics of the unit boxed and ready to roll. Theres a Dalek meet at the national coal museum in W.Yorkshire UK so im hoping to power up and do a full test of the Circuit......if the weather holds that is.
     
  8. Fenris

    Thread Starter Active Member

    Oct 21, 2007
    288
    2
    Hi all

    Heres a picture of the finished unit I was working on.
    Pleased to say it all works very well and 17 of them
    are currently in the hands of their new owners and a
    further 10 have been requested. A big thanks to every
    one who helped me sort out the various questions, confusions
    and general "erm now what's" from me :D

    regards

    Fenris
     
  9. Fenris

    Thread Starter Active Member

    Oct 21, 2007
    288
    2
    Hi All

    Just to dig this thread up here is a link to a youtube video of Nick Briggs (the voice of the daleks) Also featuring Colin Baker (the 6th Doctor) having ago on my voice mod :O . The dalek it is installed in is D4 built and owned by Richard (the guy on the right dressed as the 10th Doctor). How fat headed do I feel :D


    http://www.youtube.com/watch?v=Pa4SpnhmYf0

    regards

    Fenris
     
  10. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    OMG!

    I remember him well, I would not have recognized Colin now, though having been introduced again I can see it is the same person. I always wondered in Tom Baker was related, similar name, similar features.

    Here is what I'm talking about...


    [​IMG] .. [​IMG]

    It's very sad, we've both gotten older and gained weight. Very sad.

    Were you in that clip by chance Fenris? BTW, were did that name come from, if I might ask?
     
  11. Fenris

    Thread Starter Active Member

    Oct 21, 2007
    288
    2
    Hi Bill

    No their not related though I do take your point :D Colin baker was a star in a British soap called the brothers. Basically the story of in fighting amongst family members who ran a transport company. He was what Larry Hagman was to Dallas :D He was regularly accosted by old ladies on the street 'for being so nasty' :D

    I to am spreading in ways I find slightly saddening ;) Yet another thing they don't teach you in school :D

    I have a liking for many myths and legends particularly Norse mythology. Fenris was a giant wolf, who, at the battle of Ragnarok ate the moon before getting put down! I am a lot tamer I'm glad to say.

    Sadly I was not there But Storm was with the lights! Nick Briggs thought he was brilliant and mentioned how good he would look 'on the show'. Alan has given him his card :D . Colin Baker said 'Now thats what I call a Dalek!'

    regards

    Fenris
     
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