Dew Control

[ZeroID (Brent)]

Had some dew problems on the guide scope the other night. The Lunt already has a heater but not the 80F5. So trying a simple solution first. I don't have dew problems very often but this was pointing almost to zenith.
Made a replacement dew shield from a cardboard Single Malt Whisky tube that was about the right size. Hacked a hole in the side and fitted a small 12v fan to blow across the lens front. I've got a 5 v and 12 v feed to the mount on a selectable switch give me two speed options. See if that manages to cope with the occasional dampness.

[Imme (Jon)]

This chemical handwarmers do wonders for that every now and then use......and very cheap fix

[redbeard (Damien)]

Keen to hear how you go. Sounds like a great solution. No heat to worry about and easily powered, (low current draw)!

Cheers,
Damien

Originally Posted by ZeroID

Had some dew problems on the guide scope the other night. The Lunt already has a heater but not the 80F5. So trying a simple solution first. I don't have dew problems very often but this was pointing almost to zenith.
Made a replacement dew shield from a cardboard Single Malt Whisky tube that was about the right size. Hacked a hole in the side and fitted a small 12v fan to blow across the lens front. I've got a 5 v and 12 v feed to the mount on a selectable switch give me two speed options. See if that manages to cope with the occasional dampness.

[ZeroID (Brent)]

Originally Posted by Imme

This chemical handwarmers do wonders for that every now and then use......and very cheap fix

Not much room to attach one of those, most of the lens cell is plastic so a lot to get through and pointing to zenith in this case all the heat would just go straight up. The fan is only a cm or so in front of the lens itself and at 5 v is undetectable for vibration.

> Damien .08 amp current. It's off a Radeon Graphics video card. I just used a few drops of heat gun glue to secure it to the tube. I have a few spare if you want one.

Start drinking that Single Malt ....

[Atmos (Colin)]

The single malt not only helps keep dew at bay it also keeps the operator warm too!

[redbeard (Damien)]

Originally Posted by ZeroID

Not much room to attach one of those, most of the lens cell is plastic so a lot to get through and pointing to zenith in this case all the heat would just go straight up. The fan is only a cm or so in front of the lens itself and at 5 v is undetectable for vibration.

> Damien .08 amp current. It's off a Radeon Graphics video card. I just used a few drops of heat gun glue to secure it to the tube. I have a few spare if you want one.

Start drinking that Single Malt ....

Yep sure am thirsty now!

Thanks for the mention of the fan, but I have a couple floating around.

Cheers,
Damien

[boz_m (Alexander)]

Why are dew control straps and boxes so expensive? Seems like such a low cost thing.

Is there any alternative that you can use (home brew heater straps, etc)?

[luka]

Originally Posted by boz_m

Why are dew control straps and boxes so expensive? Seems like such a low cost thing.

Is there any alternative that you can use (home brew heater straps, etc)?

Plenty of home brew solutions. See, for example, the other current dew control thread. Plenty more examples if you search the DIY section on IIS and also google is your friend.

[ZeroID (Brent)]

I bought it some 12-35 volt DC @ 8Amp motor controllers for another cooled camera experiment earlier, about 4 of them. They were only $5.00 each. A Nichrome DIY heater and one of these would allow some control. I also brought in a temp sensor unit (~$14 ) and 6 sensors. easy enough to keep an eye on it depending on the night. Total cost about $25 for the lot. Would work in the field or Ob on the 12 volt line.

[Imme (Jon)]

Originally Posted by boz_m

Why are dew control straps and boxes so expensive? Seems like such a low cost thing.

Is there any alternative that you can use (home brew heater straps, etc)?

I’ve just made a brew strap one with a light dimmer switch as a controller.....works amazingly and was only $30

[glend (Glen)]

Originally Posted by Imme

I’ve just made a brew strap .....

Haha perhaps too much '-Single Malt was used.

[ZeroID (Brent)]

Well, mini fan @ 5 volts seems to be sufficient for my requirements although the dew factor wasn't quite as bad as the other night. Shame it doesn't work on clouds ...

The Single Malt was quite effective too .... Auchentoshen 3 Wood