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Old 26th Nov 2017, 11:12 am   #1
Bobsound
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Default ExpressSCH Symbols

I am grappling with the above software at the moment and am wanting to use valve symbols.
Unsurprisingly there are no such symbols in the library and my attempts to put a symbol together have so far not worked.
Have any of you found a solution to this? Are there perhaps any other libraries out there with suitable symbols?

Thanks

Bob
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Old 28th Nov 2017, 1:30 pm   #2
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Default Re: ExpressSCH Symbols

https://www.expresspcb.com/guide-to-...or-expresssch/

Is this no help?
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Old 28th Nov 2017, 1:45 pm   #3
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Default Re: ExpressSCH Symbols

Chris

Thankyou for your reply. Yesterday I made a concerted effort to get to grips with this and I am now happy to say that I think I have mastered component construction (The product of a rainy day and retirement).

I have a pentode, beam tetrode, double triode and cascoded double triode created. If these are of any use to anyone, I am happy to try and e-mail them.

Bob
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Old 28th Nov 2017, 9:04 pm   #4
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Default Re: ExpressSCH Symbols

Well done! Creating symbols in some packages can be a right PiTA.

Probably "So simple, so very simple, that only a child can do it"

(Tom Lehrer, New Math)
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Old 28th Nov 2017, 11:02 pm   #5
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Default Re: ExpressSCH Symbols

I have also created Valve symbols with Express, also various Transformers and Chokes, as well as IC's. Once you get the hang of it, it's fairly easy.

I have not tried PCB side of it however.

I use Linux Mint and WINE, which can be a bit tricky as it does not always react as you might expect
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Old 29th Nov 2017, 11:19 am   #6
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Default Re: ExpressSCH Symbols

I too have yet to try the PCB side of things but I am now more confident having sorted out the schematic functions.

The only slight problem I have, being an old f**t brought up on Practical Wireless diagrams, is the crossing of lines without connection; there being no option to produce a 'bridge' to show no connection.

Bob
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Old 29th Nov 2017, 3:24 pm   #7
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Default Re: ExpressSCH Symbols

As to the PCB aspect of things, I've been making my own PCBs for decades, either to my own design of from magazine articles, but I steer well clear of PCB CAD packages such as Express PCB.

It's evident that the software is primarily intended to design PCBs your own PCBs to be professionally made by them - not by DIY means. The tracks are far too narrow and the pads too small for home production. This is exacerbated by 'undercutting' of the tracks and pads during etching. That's not to say that others haven't successfully used the package to make homebrew PCB - I've no doubt that many have, but I see no point in setting myself up to fail by etching away large areas of copper needlessly.

Etching time is largely dictated by how much copper is to be etched away, and what generally happens is that the copper adjacent to tracks first begins to etch away, then quite large areas still need to be etched away, and during that time the etchant begins to etch sideways under the tracks and pads. As the tracks and pads created by Express PCB are so narrow to begin with, you end up with a fragile PCB and need to be very precise when drilling the pads, which risk lifting when a soldering iron is applied.

Of all the many examples of magazine artwork I've used to etch boards since the 1960s, for the same reason, I never used artwork in Elektor - simply not designed for DIY PCB creation. If - as occasionally happened - I wanted to build an Elektor project, I always bought the PCB from Elektor, which often cost less than the magazine itself and were excellent. On the rare occasions I used their artwork I beefed up the tracks and pads to make them more 'DIY friendly'. I've attached an example - it's a little PCB from Elektor many years ago for a small regulated 100mA power supply using 78xxx voltage regulators.

The tracks on the Elektor artwork were thin and the pads needlessly small so what you see below in the first pic is the artwork after I 'beefed up' the tricks and pads. But were I to etch that PCB today, It wouldn't look like that at all - I'd leave as much copper on the board as possible - it's taken me ten minutes to amend the artwork to cover areas of board which don't need etching away at all. All the holes are in the same place, the component layout is the same, but it would be much quicker to etch, and no risk of a drill slipping and miss-drilling a pad.

This is just my view based on practical experience gained over many years - I'm not knocking Express PCB, but there's no such thing as a free lunch - really, they want to make the PCB for you. As home-brewers, we can maximise our chances of success by adapting our approach t be more suited to DIY PCB production. I hope I've not provoked a 'snowstorm' of exquisite PCBs created, etched, drilled, tinned and built by forum members using Express PCB. If so, they have my admiration!

Hope that's of interest.

Every good wish with it, whatever your intentions.
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Old 29th Nov 2017, 6:49 pm   #8
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Default Re: ExpressSCH Symbols

David

thankyou for your insights. The last PCBs I made were a number of years ago using the black sticky tape and an RS UV exposure box.

Do you use the sticky tape or a resist pen or some other technique?

Bob
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Old 29th Nov 2017, 7:25 pm   #9
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Default Re: ExpressSCH Symbols

You can usually set up design rules in PCB packages for home use. Just set your track width and spacing based on what you can do and you’re done. I’m using Kicad for this. I did a single layer board last week. Managed to ruin it by over etching. The brilliant thing is when you get fed up, you can hire someone else to deal with it. I got OSHpark to make three boards for 7.24 which I figured was better return on my small volume. Plus they’re solder masked, ENIG (gold) finish, silk screened, plated vias etc and good to 4 layers.

Just did three more tiny little SMD boards the other day for a pulse generator which were 2.33 for 3!

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Old 29th Nov 2017, 7:41 pm   #10
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Default Re: ExpressSCH Symbols

Quote:
Originally Posted by Bobsound View Post
thankyou for your insights. The last PCBs I made were a number of years ago using the black sticky tape and an RS UV exposure box.

Do you use the sticky tape or a resist pen or some other technique?
I create the artwork in MS 'PAINT' then to make the UV mask, I use an ink-jet printer to print the artwork onto 'micro-porous film' used for screen printing, which is far superior to normal OHP film. I don't use pre-sensitised UV laminate, I haven't done for some years as their exposure time seems rather sensitive and I always ended up with useless offcuts. For some years I used positive UV lacquer, self-sprayed from aerosols. If the board doesn't come out right, I'd then wipe off the UV resist with meths (AKA 'de-natured alcohol outside the UK) and re-spray the lacquer and have another go. However, this last year or so I've been using negative UV 'dry film' which is very cheap on e-bay from China. It's basically a layer of UV dry lacquer with a clear protective film on each side.

You peel off one side of the film, (doesn't matter which), and place it on your PCB laminate, carefully excluding any air bubbles, then pass it through a normal laminator to seal the film to the board. (I guess you could use an electric iron on a low setting with a cloth placed over the board). Along with the mask, you then place it in the UV box and expose it. (Around 60 - 75 seconds), then peel off the second protective film and develop it using soda ash as a developer, which is harmless. The film of resist that it leaves on the board is excellent - much thicker than pre-sensitised or self-sprayed positive resist.

It's very simple to create a negative image for the mask from a positive one in a matter of seconds. In 'PAINT' you select the positive image, right click anywhere on it, and an 'Invert Colour' option appears. Click on that, and everything that was black becomes white. There's an example below, of a PCB I designed for the AM/FM Converter. I always print two images in case one doesn't quite print correctly of if I need to double them up. The top two are positive images, so everything that's black will remain on the board and everything transparent will be washed away when exposed and developed. In the bottom two negative images, only the clear parts of the image will remain after exposure and developing - all the black areas will be washed away by the developer. After etching, the resist in removed very quickly by placing the board in acetone.

The only problem with the film is that if there are any bubbles laft when the film has been passed through the laminator, the resist will tend not to adhere to the copper, so after exposure and developing, you need to carefully check the board with a magnifier to ensure that there are no flaws in the tracks. If there are, they need repairing, ideally with rub-down PCB transfers. Unfortunately, Seno have stopped printing the transfers, but through the kindness of forum members, I now have enough to keep me going, though I try not to have any bubbles in the film!

I don't think it's a topic that excites the interest of many on the forum, but there have been a couple of threads on the topic this last year or so, which might be of interest to you Bob:

https://www.vintage-radio.net/forum/...d.php?t=137818

https://www.vintage-radio.net/forum/...=132065&page=2
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Old 29th Nov 2017, 8:15 pm   #11
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Default Re: ExpressSCH Symbols

That's very interesting, David. I don't have MS Paint myself but I've probably got a similar software package somewhere once I get organised!

I've got a couple of valve projects on the go first which will be point to point wired but i have got a pre-amp/control unit to build using semiconductors so i will want PCBs for that.

Thanks

Bob
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Old 29th Nov 2017, 8:51 pm   #12
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Default Re: ExpressSCH Symbols

Quote:
Originally Posted by Bobsound View Post
That's very interesting, David. I don't have MS Paint myself but I've probably got a similar software package somewhere once I get organised!
Perhaps you don't use Windows Bob, but if you do, PAINT is bundled with that. There are lots of tutorials on youtube.

Others have said that the free paint.net is just as good (some say it's better), than PAINT, but I have no direct experience of that:

https://paint-net.secursoft.net/?net...tent=paint-net

Have fun - good luck with your valve projects Bob!
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Old 30th Nov 2017, 4:47 pm   #13
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Default Re: ExpressSCH Symbols

I have found Paint!
Thanks David
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Old 30th Nov 2017, 6:50 pm   #14
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Default Re: ExpressSCH Symbols

It's very basic, but the ability to modify drawings pixel by pixel can be very useful for "cleaning up" grotty scans of dodgy originals.....

If you capture a circuit online as a screen shot you can just paste into Paint and change as you like. Useful on here, that, sometimes.
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