QHY8 Nosepiece dewing solution

[SteveL]

Hi all

This message is aimed squarely at the QHY8 owners, especially the ones who are experiencing dewing on the outside of the nosepiece glass in humid conditions. This issue has plagued me for a while, but I have now found a reliable solution!

Maplin do a 3A Digital Car Power Adaptor:

http://www.maplin.co.uk/module.aspx?moduleno=115314

And I have used this a few times with the correct power tip (supplied) to supply the TEC (the round plug/socket) with 9v instead of the usual 12v. I have also stressed tested this in the kitchen while cooking a roast and boiling lots of vegetables, so the kitchen was very very humid. At 12v, the dew spot appeared pretty soon after I applied the power. When I removed that and supplied it with 9v, the dew spot visibly shrank and disappeared.

As the QHY8 uses a Sony chip, the noise levels in the images will not be affected by much (or at all!).

I just thought I`d mention it here, i case it is useful to someone.

[Beyond_Vision]

Presumably all that has done is limit the amount the camera can cool by.

The widget is quite interesting as it can be used to run from a 24V battery and regulate to 12V giving a monitor of voltage and current drawn. It will automatically switch off the power before the battery is exhausted. This would help to extend battery life as completely exhausting a battery can severely shorten it's life. This would be great to run dew straps from as these often can completely drain a battery during a session.

Regards

Kevin

[Erwin Kats]

wrong post sorry

[PortableAstronomer]

Thanks for this tip steve.

I have a QHY8 and I thought the lead for the TEC input provides +18V and -18V ( potential difference of 36V ) ; so supplying it with +9V with zero ground would reduce the effective voltage supplied to the TEC to 1/4 of of the original.

But no worries, it obviously works for you, I'll probably pop out to Maplins and get one if I can find one. Keep up the great posts

Regards, Chris

[Beyond_Vision]

The power supply output to the TEC is seperate from the camera electronics supply. Steve has probably fitted this regulator device in line with this output of the QHY PSU not it's input supply.

In theory it's also possible to create a PSU that takes in a low DC voltage and gives out a higher level +/- supply rail.

Regards

Kevin

[SteveL]

The TEC and the fan are run from the 12v supply (the round 2.1mm plug), its the S-Video that provides the 18v feeds to the camera electronics. If i supply 12v to the TEC, it fogs up under the same circumstances as if I plug it into the normal QHY8 power box.

[PortableAstronomer]

I've got to try this out. Sounds very interesting. Thanks again.

[PortableAstronomer]

I've also been trying it out now.

It works a treat. Many thanks for the tip.

[SteveL]

glad I could help...