(15-02-2013, 12:41 PM)Joe Wrote: [ -> ] (08-02-2013, 09:10 PM)Yorkie Wrote: [ -> ]Really, the whole thread has become rather like a large helping of alphabet spaghetti, and is in need of a good spring clean, which I think will be attended to. As it stands, it would probably take longer to read the thread than to build the project!
A condensed version is now available here.
Because its Friday, here's a REAL can of Condensed Alphabetti Spaghetti
[
attachment=7197]
I bet there are fewer letters in that can than in my ESR meter posts Nick!
I'm most grateful to Joe for his time, trouble and expertise in bringing together in one neat PDF document all of the relevant info from this thread which is needed to succesfully build this useful little project. Many have been built over the last couple of years or so, and presently, a new forum member is building one. I'm sure he'll find Joe's PDF file most useful.
The parts are on the way and I'll be giving the construction of this meter a go. I want to use the PCB and I'll be trying to etch the board myself. This will is my first time with this process and I have a problem with scaling the pcb image to print for transfer to the board. I do have the skill and software to size the image and print size if I knew the dimensions.
I feel a little lost, this wasn't something I thought about have trouble with. Bet it's a simple and remedial fix.
I may put off building the great looking wood enclosure until after I get more experience at board building.
Dana Locke
Missouri, USA
I've just printed the PCB layout in post 40 and it came out the right size with no scaling. That was using Microsoft Photo Editor.
- Joe
Hi Dana,
Sorry to hear of your hassles.
Like Joe, I've just printed off the article at the link he set up, and the PCB artwork comes out the correct size.
The image as it appears, including the white border, which allows for holes at each corner to mount the PCB, should be 5.46cms high and 8.92cms wide. (In inches, that's 2.15" high and 3.515" wide). The height and width of the actual PCB tracks on the artwork (not allowing for any border) is 5cm high and 7.5cm wide. If you are using something like Photoshop, if you do need to re-size, just set one dimension it should automatically set the other. The easiest way to check if you have the artwork the right size is to sit a 14-pin IC socket on the artwork and see if the pin spacing on the PCB is the correct size to marry up with the IC socket.
If you intend to use the 'iron on' method to apply the artwork to the PCB rather than UV exposure, (either the laser printer onto glossy magazine paper or glossy photo paper, or the 'press 'n peel method), do remember that you must 'flip' the artwork or your design will iron onto the PCB the wrong way round. The tracks on the finished PCB must look like the artwork.
As to etchants for making PCBs, I've long since abandoned messy ferric chloride in favour of Sodium Persulphate copper etchant. This is an effective alternative to ferric chloride which has a 6 – 8 minute etch time at 45C – 50C. The bath life is about 4 – 6 weeks depending on use and operating temperature. The product is supplied as a fine crystalline white powder and the instructions for use are printed on the bottle label. You mix it with warm water and it's a colourless liquid which in use, turns pale blue as it etches away the copper. You can store it for re-use till it loses its effectiveness.
I don't know how you are fixed Stateside for obtaining such chemicals - maybe you'll have the Dept of Homeland Security knocking on your door searchng for WMD!
In the UK it's easy and cheap to buy on internet:
EG: a 500 gram HDPE bottle, which will make up to 2.5 litres of etching solution costs just £3.50GBP +£2.24GBP P&P
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=270746775207&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
Best of luck with the project Dana - many have been built over the last three years or so and help is on hand if you need assistence in trouble-shooting.
(12-03-2013, 10:18 AM)Joe Wrote: [ -> ]I've just printed the PCB layout in post 40 and it came out the right size with no scaling. That was using Microsoft Photo Editor.
- Joe
Heh. I thought it might only be a simple fix. Just needed to fix me I guess. I've been referencing the condensed file you put together. Got lazy and didn't go back through the earlier posts again, I just made a bee line for the most excellent all in one file whenever I wanted to revisit the parts list or othcer info.
Printing from the pcb image in post 40 worked well and is, by the way, much easier than cutting the image from the condensed article in post 50 and pasting it into Gimp (Linux) and then scaling from there.
Re:
A condensed version is now available here (
http://golbornevintageradio.org/forum/at...p?aid=7215)
Thanks Joe.
Dana Locke
Missouri, USA
(12-03-2013, 12:26 PM)Yorkie Wrote: [ -> ]Hi Dana,
Sorry to hear of your hassles.
Like Joe, I've just printed off the article at the link he set up, and the PCB artwork comes out the correct size.
The image as it appears, including the white border, which allows for holes at each corner to mount the PCB, should be 5.46cms high and 8.92cms wide. (In inches, that's 2.15" high and 3.515" wide). The height and width of the actual PCB tracks on the artwork (not allowing for any border) is 5cm high and 7.5cm wide. If you are using something like Photoshop, if you do need to re-size, just set one dimension it should automatically set the other. The easiest way to check if you have the artwork the right size is to sit a 14-pin IC socket on the artwork and see if the pin spacing on the PCB is the correct size to marry up with the IC socket.
If you intend to use the 'iron on' method to apply the artwork to the PCB rather than UV exposure, (either the laser printer onto glossy magazine paper or glossy photo paper, or the 'press 'n peel method), do remember that you must 'flip' the artwork or your design will iron onto the PCB the wrong way round. The tracks on the finished PCB must look like the artwork.
As to etchants for making PCBs, I've long since abandoned messy ferric chloride in favour of Sodium Persulphate copper etchant. This is an effective alternative to ferric chloride which has a 6 – 8 minute etch time at 45C – 50C. The bath life is about 4 – 6 weeks depending on use and operating temperature. The product is supplied as a fine crystalline white powder and the instructions for use are printed on the bottle label. You mix it with warm water and it's a colourless liquid which in use, turns pale blue as it etches away the copper. You can store it for re-use till it loses its effectiveness.
I don't know how you are fixed Stateside for obtaining such chemicals - maybe you'll have the Dept of Homeland Security knocking on your door searchng for WMD!
In the UK it's easy and cheap to buy on internet:
EG: a 500 gram HDPE bottle, which will make up to 2.5 litres of etching solution costs just £3.50GBP +£2.24GBP P&P
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=270746775207&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
Best of luck with the project Dana - many have been built over the last three years or so and help is on hand if you need assistence in trouble-shooting.
Great info. The dimensions are exactly what I needed. Well, that and you and Joe's reference to the image in 40 printing correctly with no scale issues. I had no problem printing from that image either. I'd been using a cut and paste from the pdf that Joe put up on 50. I may still make some adjustments to the image with this sizing info.
Could not use the IC to check the print size as it had not arrived yet. Could have use a 5mm radial Electrolytic cap or even calipers and a rule I suppose. I'll probably do this on all my images before to make sure the image is correctly scaled before dropping the board into the etch. Nice to avoid making a rather unattractive coasters out of them.
Nearly all of the remaining components and a pair of 50uA meters from Hong Kong (whew) arrived today. I only need to decide on a suitable project box and decide which pair of test probes to grab in order to move along.
I have been researching the different etch solutions and various methods of resist and I am going to try the Laser print/iron on/wash/etch/and rinse method. I'll use the photo or glossy paper you suggest but I'm not comfortable running magazine slicks through my printer.
Like you, I've decided against ferric chloride as it appears to be bit nasty. I decided on cupric chloride for the etching solution. I have purchased 30% hydrochloric acid (muratic acid used to clean concrete and cement) from the neighborhood Ace Hardware store at about $4.79 US for a quart container, and a pint bottle of 3% hydrogen peroxide from the pharmacy/hair care department at Walmart for $.52 US. I understand that a proper mix of these two will give good results, stores well, and is reusable indefinitely with a bit of refreshing now and then.
I don't know much about Sodium Persulphate. I must say it sounds right. Easy to use, cheap price, stores well. If the cupric chloride should prove to be a disappointment I'll certainly give it a try.
I'm looking forward to putting this little beasty together and getting intimate with some bad, component killing, high ESR caps!
Thanks for all the great info and help. It's much appreciated.
Dana Locke
Missouri, USA
(13-03-2013, 07:09 AM)Difficilus Wrote: [ -> ]I only need to decide on a suitable project box
You need one of David's splendid wooden boxes but unfortunately you're a long way away
Alan
[
attachment=7437]
Glad to hear you're making progress Dana.
As to what type of test probes to use, most constructors (and commercial ESR meters) seem to use miniature 'croc clips'.
Regarding a project box, I don't think many people will want to mess about making a wooden box - I've just got into the habit of making comb-jointed boxes for all my home-brew test gear, using a home-built router jig, because woodworking and woodturning are parallel interests. I've attached a pic that was sent to me by another constructor of a recently built meter in a plastic project box. (The dial has not been calibrated yet).
As I've been making PCBs using the time consuming and sometimes inconsistent UV light box method for years, I'm in a rut as deep as a grave, and don't have a laser printer to experiment with, so I just plod on with UV. However, there's a lot of information on internet about the laser 'iron-on' method which seems to give good results and cuts out the need for either self-spray lacquer/expensive pre-sensitised PCB, getting the UV exposure right, and getting the correct strength of developer, or either the whole design disappears before your eyes, or nothing happens. Hard to get consistent results with UV.
I take your point about not wishing to risk magazine paper in your printer. An interesting process though. I don't know what 'junk mail' comes through your mail boxes in Missouri but in the UK, we get a lot of glossy 'free sheets' - advertising material, printed on glossy paper.Some paid for magazines use thicker higher gloss paper which is probably better. Because printers' ink is used on that paper, it is colour fast, so it matters not that a page is covered in print - you don't need to find a blank piece. You just cut the paper to A4 size, feed it into the printer, print out your design and iron it one then soak the paper off in warm water, leaving the laser printed design and nothing else on the PCB. Or so the story goes - I haven't tried it, but I can see the attraction.
Good luck with the etchant - dont buy too much hydrogen peroxide or Langley will have you in their cross-hairs!!
Don't forget to 'flip' the image or you'll have a back to front PCB!