Dew Heater Controllers

[Dr_Ju_ju]

For anybody who wants to make their own heaters using nichrome wire etc. I found these on eBay http://www.ebay.co.uk/itm/4pcs-DC-12V-24V-Dimmers-Controller-Brightness-Adjustable-for-LED-Light-Strip-UK-/291057145393, and for the price are a bargain.

The control modules can easily be removed and re-fitted into a case of your own choosing, with suitable connectors etc...

[Tommohawk]

Yep am busy with DIY dew controller and saw these on #bay too. 

Looks like theyre mostly marketed at LED controllers. Does anyone know if any LED controller (with sufficient rating) would do the job?

[Gina]

I've used those in the past.  Only trouble was that some of them didn't last long

[philj]

I never got the chance with mine, I ordered some and they never arrived, got me money back though.

[Mick J]

I have seen these used in a few diy's on sgl, a fine how to;

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

from another sgl member.

[Tommohawk]

I have seen these used in a few diy's on sgl, a fine how to;

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

from another sgl member.

OK thats fab. The controller shown in the Blackwater link uses the same item the OP referred to. Sounds good to me.

There's also a three Channel controller on Maplin which might do the job:

http://www.maplin.co.uk/p/12-v-dimmer-for-rgb-led-tape-light-recommended-for-use-with-nj961-tape-r62pe 

Was thinking about this as ready made controller for Secondary, Primary and guide scope. £17.99 at Maplins, or available from #bay much cheaper, but only from Far East.

[Mick J]

Hi Tommo,  I am not to up on these things, and am sure better advice will be coming, but I can find a controller that looks just like the maplin on ebay (uk) a bit cheaper but better info on page, rated at 3 Amps/channel.  Original ebay listing was 4 controllers at 8 Amps each,  guess you have to do your sums,  what will your bands draw.

[Tommohawk]

Hi Tommo,  I am not to up on these things, and am sure better advice will be coming, but I can find a controller that looks just like the maplin on ebay (uk) a bit cheaper but better info on page, rated at 3 Amps/channel.  Original ebay listing was 4 controllers at 8 Amps each,  guess you have to do your sums,  what will your bands draw.

Good spot - I missed that. I've just bought one, and I'll post back when I've had a chance to check it out.

They're also available from HK for £7.96, but I bet returns are interesting.

Re current - 3A at 12V is 36W per channel - that should be heaps. Only the huge ones draw more tha a couple of amps. Not sure if the unit has protection though, so will fit inline fuses.

Cheers

[faulksy]

i used theses and found they did run hot, even in a different box(i.e. removed from the original box) in the end i used some pwm from maplins they will carry 6 amps each and have a big heat sink. havnt had any problems.also consider, whilst making your own to your own spec with extras, and obviously buying all your connectors cables fuses e.t.c. you can buy one for less. mine cost around 80 quid to make

[SkySurfer]

Those that the OP posted are the ones I have used for dew controllers, as they are PWM controllers which is exactly what you want, they are rated at 9amps 96watts each controller, so,you could run two dew straps comfortably off each one, this is what someone else on here did, using them, looks good too

http://stargazerslounge.com/topic/225970-diy-mount-power-hub/

SS

[SkySurfer]

Those that the OP posted are the ones I have used for dew controllers, as they are PWM controllers which is exactly what you want, they are rated at 9amps 96watts each controller, so,you could run two dew straps comfortably off each one, this is what someone else on here did, using them, looks good too

http://stargazerslounge.com/topic/225970-diy-mount-power-hub/

SS

Sorry 8 amps not 9

SS

[faulksy]

they would fry the timer at 8 amps, they got hot running 1 amp and that was all 4 i bought.maybe a faulty batch

[SkySurfer]

Well I use the same controllers that the first post shows from ebay, and I run two dew straps which fully on draw 5 to 6 amps, on one of those controllers and runs all night if I need it too, I took the electronics out of the origonal box and rehoused but apart from that they are as they were when bought, I don't really notice any heat from the controller, they are rated to 8 amps or 96w so should work up to that comfortably, so of you spilt the output to two ports you should be able to run 4 amps on each.

I bought those exact ones, and trust me they are absolutely fine

SS

[SkySurfer]

Well I use the same controllers that the first post shows from ebay, and I run two dew straps which fully on draw 5 to 6 amps, on one of those controllers and runs all night if I need it too, I took the electronics out of the origonal box and rehoused but apart from that they are as they were when bought, I don't really notice any heat from the controller, they are rated to 8 amps or 96w so should work up to that comfortably, so of you spilt the output to two ports you should be able to run 4 amps on each.

I bought those exact ones, and trust me they are absolutely fine

SS

You can just see in the pic, where it says on them 8amps

SS

[Mick J]

Re current - 3A at 12V is 36W per channel - that should be heaps. Only the huge ones draw more tha a couple of amps. Not sure if the unit has protection though, so will fit inline fuses.

Cheers

Ian's guide to home made bands has a calculator that may help,  we made ours a long time ago, nichrome wire after having resistors short out (not sure what we did wrong but was messy-not on the scope).  Found heat shrink over nichrome between 2" velcro worked well, connector strip for nichrome/cable glued to velcro.  We used Velleman K8004 PWM kits for control, these cheap led dimmers were not around, spec looks much the same.

[jason.p]

This is my attempt. I might fix the controllers inside a box one day. Running a primary, secondary and finder. I've since added an uncontrolled Telrad strip.

[Tommohawk]

Thats nice - like the colour coded plugs! Out of curiousity, what sort of secondary heater do you have?

[jnb]

Yep am busy with DIY dew controller and saw these on #bay too. 

Looks like theyre mostly marketed at LED controllers. Does anyone know if any LED controller (with sufficient rating) would do the job?

In principle yes. LED controllers are basically pulse width modulators. So you do need to check that the equipment is up the coping with the maximum draw ie they never run at 50% but at 0%, 100%, 0%, 100% and so on. Also I have my doubts about the reliability of those cheap imported units. I built a power tank with a three channel LED controller for dew control and all three channels blew in one evening! I'm replacing that three channel unit with exactly those above. Initially as an external unit but if that survives then I'll build them into the power tank.

[Tommohawk]

Good spot - I missed that. I've just bought one, and I'll post back when I've had a chance to check it out.

They're also available from HK for £7.96, but I bet returns are interesting.

Re current - 3A at 12V is 36W per channel - that should be heaps. Only the huge ones draw more tha a couple of amps. Not sure if the unit has protection though, so will fit inline fuses.

Cheers

B*gger. Just seen the same thing on Amazon for £6 inc. p and p.

[Tommohawk]

In principle yes. LED controllers are basically pulse width modulators. So you do need to check that the equipment is up the coping with the maximum draw ie they never run at 50% but at 0%, 100%, 0%, 100% and so on. Also I have my doubts about the reliability of those cheap imported units. I built a power tank with a three channel LED controller for dew control and all three channels blew in one evening! I'm replacing that three channel unit with exactly those above. Initially as an external unit but if that survives then I'll build them into the power tank.

Ahh. Well as you say the cheapo imports may be suspect. I've ordered mine from UK supplier so at least should be able to return if dodgy.

But the ones you are now using, mentioned by the OP and by Jason P,  are also super cheap, no? I guess there may be cheap and good and also cheap and nasty.

I'll let you know how mine works out.

[jnb]

Ahh. Well as you say the cheapo imports may be suspect. I've ordered mine from UK supplier so at least should be able to return if dodgy.

But the ones you are now using, mentioned by the OP and by Jason P,  are also super cheap, no? I guess there may be cheap and good and also cheap and nasty.

I'll let you know how mine works out.

Yes the ones I'm using now are super cheap but they are three separate units so I'm less likely to have a common fault across all three channels.

[IanL]

I have been using the single channel eBay ones for well over a year now with no problems of overheating or failed units. I have bands for a couple of 80mm refractors and a 200mm SCT which I tend to run at full a lot of the time. I put a spare channel on the controller box just in case so I didn't end up losing a night due to gremlins, never needed it. Also bought a spare unit which is still in the box.

Compared to a commercial model spending another 12 quid on spares still adds up. You could put a heatsink on the chip if you were running a big band but mine don't get excessively hot. I guess with anything this cheap quality may vary but so far I am happy

[Tommohawk]

Maybe I should have gone single channel, as per the OP, and as you guys say. Anyhow, I've got the 3 channel on order and will only be running about 200mA on one channel and maybe 500mA on the other 2, so hopefully not too stressed.

[jason.p]

Thats nice - like the colour coded plugs! Out of curiousity, what sort of secondary heater do you have?

The secondary heater is a velcro strip fitted round the mirror body fed by fine wires taped to the vanes.

(Thanks Rusty!)