Drill Speed Controller for 12V PCB Drill (Query).

[Mark Hennessy]

Looks good

It might be worth edging D3 away from the MOS-FET - the left-hand end of D3 could be in line with the left-hand pad for SK2 with issues. Doing that increases the space available for a heat sink, if required.

C3 might be better being nearer to IC2, as it's primarily there to keep it stable. It might not matter, but it would be good practice.

Cheers,

Mark

[Nick]

David - c5 must be very close to the 78l05 output and c3 should be 330nF not 100nF.

[ppppenguin]

This is why I like to lash it together on a bit of pin board rather than make a PCB. If you're prototyping something with lots of surface mount chips then a PCB is the only way but for something this simple why even bother with a PCB at all. Especially as it's a one-off.

[Yorkie]

Thanks once more for the helpful advice guys.

I've modified the layout and the track-side mask accordingly, as follows:

1) D3 moved to the right, away from the MOS-FET - the left-hand end of D3 aligned as suggested, with the left-hand pad for SK2 to increase the space available for a heat sink if required.

2) C3 repositioned - now adjacent to IC2 output, and its value changed from 100nF to 330nF.

3) C5 repositioned to be adjacent to IC2 input.

Amended layouts of component side and track side  are attached.

Hope that covers all aspects!

[Yorkie]

I've made a bit more progress on this little project today - I've exposed, developed, etched and drilled the PCB.

I've got all the bits to hand, so hope to tin and populate the board over the next few days.

A couple of pics attached - the  first is of the board exposed and developed - the second, etched and drilled.

Thanks once more for the advice to date.

[SurreyNick]

...I've exposed, developed, etched and drilled the PCB....

That's a very neat PCB David.
I really must learn how to do this. So much better than the 'spotty' boards that I am currently limited to.
Nick

[Yorkie]

Thanks Nick.

I know that a lot of people tend to knock things up 'ugly style' to see if it works,  with the intention that if it does work, later on they'll build it neatly, which they often don't get round to doing. To my mind, that's just bodging and it's never been my style with anything I do. I'm sure that for many, they'd just knock up simple projects such as this one using strip-board, but I enjoy converting a circuit into a PCB layout,  and though it's a bit laborious to produce the PCB, it's a hobby. In the initial stages of a new project, as often as not I post and outline on here and seek advice and feedback to try to minimise any pitfalls, as I've done with this project and several other recent projects.

As to DIY PCB production, many people these days seem to use the laser printer/iron-on technique which obviates the need for an acetate mask, UV light box and developer.  But I've been using a home-brew UV light box for maybe 25 years, and I'm in a rut as deep as a grave! The main problem I've had in recent years has been getting my Epson ink-jet printer to print onto acetate as it doesn't have a setting for that and the results are dire. The printer was a huge disappointment after my aging HP printer died - it used to print superbly onto acetates. However, I discovered a youtube video (thanks to Joe, formerly of this parish), on how to jigger up the Epson printer settings to print onto acetate, and also discovered 'micro porous film' sold by Crafty Computer Paper, which is superior to OHP acetates. I make three copies to be sure, and tape them on top of each other. It produces good results.

In the unlikely event that anyone else on here has an Epson printer and wishes to print onto acetates for PCB artwork, these are the steps to follow:

‘Adjust Print Options’

Colour/B&W? Select ‘Colour’

(Although you want to print black, you must select ‘colour’ to get a full density black print when the following adjustments have been made to the printer options).

Paper: Select Epson Matte
Quality: Select High Quality

Open ‘More Options’ tab
Colour Correction: Select ‘Custom’
Click on ‘Advanced’ tab.

Colour Management: Select ‘Colour Controls’
Colour Mode: Select ‘Epson Vivid’

Colour Adjustment method Circle/Slide Bar?: Select ‘Slide Bar’.

There are six sliders:
Brightness
Contrast
Saturation
Cyan
Magenta
Yellow

Set all six sliders to maximum

Set 'High Speed' to Off.

Set 'Colour Smoothing' On.

If you tried to print a picture with these settings it would look dreadful, but that's not the aim - the aim is to fox the printer into depositing a generous layer of ink onto the film, as indeed it does.

I just save these settings as 'PCB Artwork' so that's all I have to select under 'printer options'.

As I said above, using the laser printer/iron-on technique, of which I have no experience, there's none of this malarkey!

[SurreyNick]

Ha, ha, ha, 'ugly style'.... yep, that's an apt description for my soldering method David. Now I'm definitely going to have to learn to make PCBs 
Nick

[pwdrive]

Ugly style or PCB, there's always the middle way:

https://aa7ee.wordpress.com/tag/manhattan-construction/

Lawrence.

[Mark Hennessy]

Ugly style or PCB, there's always the middle way:

https://aa7ee.wordpress.com/tag/manhattan-construction/

Lawrence.

Manhattan is quite nice, especially when done as neatly as that. An improvement on "dead bug".

If your circuit is really simple, then you can DIY a "PCB" from copper-clad board, using a sharp knife to cut through the outline, and heat from a soldering iron to remove unwanted sections (which naturally would tend to be minimised to keep labour down). For example: http://www.markhennessy.co.uk/articles/g...iments.htm

Of course, various mixes of approaches are perfectly viable. It all comes down to what resources you have, how much time you've got, how permanent the construction needs to be, how much you anticipate having to service or modify it in the future, how many you might be making, and what the electrical requirements might be. With experience, most methods are equally valid, but for RF or power, certain methods are best avoided.

Personally, I like designing PCBs, and I like using them where I can. But I'm not geared up to do them at home. For work, we have them made by a local company; no problem. For home use, while these days it's a lot cheaper than ever to get them made professionally, I tend not to bother for one-off projects. My default is still the dreaded Veroboard. Veroboard projects can look terrible, but done well, there's no reason that they should. This was discussed a few years back on UKVRRR; here's what I had to say back then: http://www.vintage-radio.net/forum/showp...p?p=134883&postcount=41