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Robert Brown's Ardiuno-based dew heater controller


JamesF

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I'm just about to embark on a build of one of these.  Has anyone already done one?

It doesn't look like a hideously complex build as there aren't that many components, though it does seem to rely on the builder working some stuff out for themselves.  Power ratings for the resistors, for example.  I'm kind of guessing that in the absence of any information then they really don't need to be rated that high.  A list of components by number would have been quite useful, too.  I can't find one of those.  I think I'm going to make my own up from the circuit diagram.  It may be that this stuff is actually all there and I can't find it because the documentation is just a bit of a jumble as a result of the design going through a number of iterations.  I'm sure I can work it all out.

James

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James

I've built Roberts dew controller and used this guide  not quite finished as loads of things on the go at the moment started it last year then found out I needed glasses couldn't read small writing anymore or solder for that matter eyes getting old and tired had my son do the soldering.... so mine is still work in progress. See attached Document from Robert albeit from 2018 page 5 for list of components

Andy

myDewControllerPro3.pdf

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20 minutes ago, fozzybear said:

I've built Roberts dew controller and used this guide  not quite finished as loads of things on the go at the moment started it last year then found out I needed glasses couldn't read small writing anymore or solder for that matter eyes getting old and tired had my son do the soldering.... so mine is still work in progress. See attached Document from Robert albeit from 2018 page 5 for list of components

I'm way too familiar with the eyesight issue :(  In the last seven years or thereabouts I've gone from having excellent eyesight to needing glasses for anything close up and for reading a monitor.

What I was looking for by way of a components list was more like:

R1 10k
R2 330
R3 1M

D1 1Nxxxx

and so on, so I could just work my way across the board soldering stuff on in the right places.  I went through the circuit diagram last night though and made such a list.  Now I just need to work out what I don't already have and need to buy.

James

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I've also just completed building Robert's myFocuserPro2 controller, so this project caught my eye ( Dammit 🤓).

I went the veroboard route as the printed circuit boards seemed awkward to source in the UK.

The guy is a genius and to publish the instructions in the Public domain for such a comprehensive device is extremely generous.

I've been tackling small DIY electronic projects for many years (right back to "Practical Wireless" back in the 1970's), so soldering and following circuits was no problem. I did struggle with the Arduino programming a bit though, never having got into them before.

The plethora of youtube videos and Robert's extensive PDFs caused me some confusion, paradoxically because of the level of detail and the multitude of variations.

When it came to uploading the firmware to the Arduino, I finally found the important instructions to edit the main .INO file to "un-remark" the included hardware add-ons and the need to copy 16 sub-directories of "include" .H files into the Arduino programming directories.

I'm glad I persevered though, because I'm pleased to say that it works perfectly, both by it's built-in buttons and LCD display and the comprehensive windows application.  I can now run that on my telescope's dedicated NUC PC, or the Ascom driver within other Astro Photography apps.

All I've got to do now is work out some way of physically attaching the stepping motor to my various scopes to allow it to be switched between them.

Edited by Astro-Geek
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I built one of these but modified it to use cheap 5v stepper (turns the POT) and Arduino/Python software for remote working - been working for nearly 3 yrs now.  If only I knew how to replace the mech POT with a programmable one .

https://www.blackwaterskies.co.uk/2013/05/a-cheap-multi-channel-dew-heater-controller/

 

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I've had a bit of a component-ordering frenzy this week and pretty much all the parts have now arrived.  I'm still waiting for the LM3808s, diodes, fans and some of the connectors, but I see no reason not to make a start very soon.  I also intend to 3d print my own case to fit everything into.  I might take that as an opportunity to finally get to grips with FreeCAD.

James

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On 12/09/2019 at 18:05, JamesF said:

How remote would you like it?  It has a bluetooth interface and it's possible to control it from a PC (either Windows or Linux).

James

I'd like to control at the individual heater level, on the heated item itself, rather than at the shared controller.

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Pretty much,  de-centralised sensors reporting wirelessly to the dashboard and on the spot heat control without a chunky controller on the mount. Still need power cabling sadly. It's just another preference..

8 hours ago, JamesF said:

What do you see as the advantage of doing that over running a temperature sensor for each heater back to the controller unit as Robert Brown does?  is it just the reduction in cabling?

James

 

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Ah, right, I see.  I imagine that could be quite difficult to achieve by assembling off the shelf components.  The requirement for some sort of microcontroller, power control circuitry and wireless comms is probably always going to mean a moderately-sized box at each point without bespoke hardware.

I'm hopeful that the one I'm building shouldn't be too much more than, say, 150mm x 100mm x 50mm, which would make it no more intrusive than the USB hub I already have on the mount.

James

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Well, pretty much all the parts have now arrived, except the 1N5822 schottky diodes, which I forgot to order :(

Done that now though, so hopefully this weekend I can get on with soldering and I'll just have to do those last.  I may need a few other bits of hardware anyhow, depending on whether I decide to use plugs to connect external components to the board or just solder the leads on.

James

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Remaining diodes now arrived.  I've not managed to get started yet though.  Work and hacking on oacapture etc. have occupied much of my time this week.  And this afternoon we drive miles into deepest, darkest Devon to a school once attended by Jonathan Edwards (World and Olympic triple jump champion) and Michael Morpurgo (probably best known for "War Horse" these days) to watch a school swimming competition which meant a rather late return.  I really must try to get started soon though.

James

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Finally got around to starting on this last night.  So far I've soldered all of the jumper connectors into place on one board, and the connectors for the Arduino.  That all took somewhat longer than expected, but I think there are something like 22 connectors on the board altogether.

I think I'll do all of the passive components next, though I'm wondering if I should check the connectivity for all of the jumpers first.

James

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Hmmm, well...

All passive components done, so I thought I'd get the Schottky diodes in.  Only I can't, because the leads don't fit through the holes in the PCB :(  I checked a spare bit of veroboard I have lying about and they don't fit through the holes in that, either.

I should probably use a micrometer gauge, but my vernier was closer to hand.  It measures the lead diameter as 1.15mm which I think is out of spec for the package.  I can find them in a different package, but not anywhere (yet) that appears to have them in stock.

In the name of making progress I might have to attempt to bodge something.  And it was all going so well :(

James

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40 minutes ago, JamesF said:

Hmmm, well...

All passive components done, so I thought I'd get the Schottky diodes in.  Only I can't, because the leads don't fit through the holes in the PCB :(  I checked a spare bit of veroboard I have lying about and they don't fit through the holes in that, either.

I should probably use a micrometer gauge, but my vernier was closer to hand.  It measures the lead diameter as 1.15mm which I think is out of spec for the package.  I can find them in a different package, but not anywhere (yet) that appears to have them in stock.

In the name of making progress I might have to attempt to bodge something.  And it was all going so well :(

James

Had a similar problem with the focuser project, ended up soldering and heatshrinking flyleads to the diode - not sure if its the best way, but sure was the quickest.

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I'm glad I'm not the only one then :)

Flyleads may well be the quickest solution, as you say.  I did try the leads in the headers for the Ardiuno as I have a few bits left over, but they don't fit there either.  The other possibility that occurred to me was soldering them to a couple of spare pin headers (as used for the jumpers), but I need to do five diodes and I'm not sure I have enough spare.

James

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Having found some spare pin headers and failed to get a decent soldered connection to them, I thought I'd try slimming the ends of the leads down with a file :)

That works, but it's a bit laborious.  I could try using the Dremel, I guess.  Even so, I reckon I need a bigger bit on the soldering iron.  I put a smaller one on to make it a bit easier to do the pin headers where there's not much of a gap between them, but the diodes are quite big compared with all the other components and need a bit more heat, faster, I reckon.

James

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