12v Hairdryer

[bosun21]

I was just about to buy myself a 12v hairdryer for those extra dewy nights. However how do the folk that own one actually power it? The ones I found are in the region of 150w - 170w which equates to around 15A! Thanks 

[Rustang]

why not a dew strap/heater!?

 

[iantaylor2uk]

I wouldn't recommend using a hairdryer - there is a possibility you could crack the glass

[bosun21]

I’ve been told that they are good for the secondary mirror 

[bosun21]

I have just ordered a heated dew shield for my Mak and a dew strap and controller for my 4” apo.

[bosun21]

41 minutes ago, Rustang said:

why not a dew strap/heater!?

 

It’s for the secondary mirror on my dobsonian and I don’t fancy fitting a heater to it with all that’s entailed.

[Guest]

I hope your hair dryer is nicely sealed up.  It could be a shocking experience 

Edited September 28, 2022 by Mike Q

[bosun21]

Just now, Mike Q said:

I hope your haird dryer is nicely sealed up.  It could be a shocking experience 

Why it’s not going to be raining!

[josefk]

Stick a lightweight dew shield even on the Dobsonian @bosun21. I have a cassegrain and a diy lightweight dew shield has made all the difference on recent nights even while every other surface around me was dripping wet (including the inside surface of the dew shield).

Edited September 28, 2022 by josefk

[bosun21]

1 minute ago, Mike Q said:

I hope your haird dryer is nicely sealed up.  It could be a shocking experience 

I have sacked the idea now and just bought a dew shield for the secondary mirror 

[Stephenstargazer]

I got a cheap 12v drier at a truck stop. Pretty feeble gentle warmth and ~3A, doubt it would dry hair or crack anything. For eyepieces I find a  big rubber air puffer (camera shop) works just as well though if they steam up when I come inside.

 

[Guest]

1 minute ago, bosun21 said:

Why it’s not going to be raining!

Moisture will find a way to get it, it always does. Given your conditions I would have probably tried a dew shield first.

[Guest]

1 minute ago, bosun21 said:

I have sacked the idea now and just bought a dew shield for the secondary mirror 

Ok.... What changed your mind? 

[bosun21]

Just now, Mike Q said:

Moisture will find a way to get it, it always does. Given your conditions I would have probably tried a dew shield first.

I have just ordered the dew shield for it. 

[bosun21]

3 minutes ago, Mike Q said:

Ok.... What changed your mind? 

The 15A ! 

[Guest]

3 minutes ago, bosun21 said:

The 15A ! 

Gotya 

[Guest]

A while back i made a light shield out of 5mm foam and velcro.  It cost about 15 bucks and 15 minutes to make.  It works very well blocking out the full moon and on nights that aren't insanely dewey... It works decently as a dew shield.  

[Carbon Brush]

A 12V hair dryer presents no risk of electric shock.
Even when standing in a pudlle with rain on your head😄

For anyone considering such a device for spot heating.
My recommendation is to use a separate battery.
At motor start, the very high inrush will cause a voltage dip on the 12V supply, risking mount shutdown, loss of position, etc.

Even if you go for a mains dryer, the RCD in the mains feed to your observing station will protect you.

I have used both mains and 12V dryers at different times.

HTH, David.

Edited September 28, 2022 by Carbon Brush
Spilling mistook

[ollypenrice]

An unheated fan blowing across the mirror might do it. Nobody seems to do this, but a Sky and Telescope article years ago said fans should blow across the mirror to break the boundary layer. Moving air is also much less prone to depositing dew.

Olly

[bosun21]

1 minute ago, ollypenrice said:

An unheated fan blowing across the mirror might do it. Nobody seems to do this, but a Sky and Telescope article years ago said fans should blow across the mirror to break the boundary layer. Moving air is also much less prone to depositing dew.

Olly

I will use the dew shield and leave the fan running on the primary mirror. That should do the trick hopefully.

[Guest]

18 minutes ago, bosun21 said:

I will use the dew shield and leave the fan running on the primary mirror. That should do the trick hopefully.

Try it with and without the fan.  Be looking for vibration. I never run a fan.  

[bosun21]

4 hours ago, Mike Q said:

Try it with and without the fan.  Be looking for vibration. I never run a fan.  

Good point, I usually only run it during the cooling down period, and switch it off before I start observing.

[Zermelo]

You can get 12V hairdryers with two power settings. The higher one will be in the region of 10A-15A but the lower will be more gentle on your power supply (and mirrors).

[ollypenrice]

4 hours ago, Mike Q said:

Try it with and without the fan.  Be looking for vibration. I never run a fan.  

Imagers have fans right on their cameras all the time without issue. You need the right kind, with contactless bearings.

Olly

[Guest]

5 hours ago, ollypenrice said:

Imagers have fans right on their cameras all the time without issue. You need the right kind, with contactless bearings.

Olly

I am certain they do, i am also very certain they are better fans then what come on the normal run of the mill dob