Sensor Dew control with Nichrome wire

[libraryman]

After considering various options i have attempted to use Nichrome wire to prevent dew build up on my sensor ready for the cold finger treatment.

It appears to test out o.k using either 3.3 volts or slightly higher 5.5 volts, the ideal may be a controller to fine tune the voltage.

Ray

 

[russellhq]

Looks good Ray. Have you reinstated the glass window on the sensor package? I'm just wondering if that doesn't have the nichrome on it, it might dew up, what do you think?

[libraryman]

Hi Russ, it appears to work ok , i havent removed the front sensor glass yet, that will be done after the cold finger completion, the front glass is warm to the touch..I put the whole sensor into the freezer and connected up to 5 volts, it cleared the dew quite quickly, so it woks but needs a control system which would be enclosed with the other control functions, I feel it would be better with 3 volts...a little cooler.

One concern is that although the front Lp1 glass is in place, it may not fit fully into its place because of the wire and may effect focus in some way..don't know yet, Haven't tested yet in the camera, waiting for cold finger copper to come!!

Ray

[JAS]

You could use one of the cheap ebay pwm led dimmers, they work at 12v but you can fine tune them to what you need, not sure what amperage you require though. And they are less than £3.

Jason.

Sent from my GT-I9505 using Tapatalk 2

[russellhq]

You could use one of the cheap ebay pwm led dimmers, they work at 12v but you can fine tune them to what you need, not sure what amperage you require though. And they are less than £3.

Jason.

Sent from my GT-I9505 using Tapatalk 2

Ray, I've got a spare if you want to try one?

[libraryman]

Cheers Russ, if you have one that you don't need then i could use it, i'll send you a PM with my address

Ray

[Luis Campos]

Hi there,

I use also nichrome wire on my cooling mods but I put the wire in very fine bore heatshrink, it fits the gasket groove on the filter frame nicelly

You must be aware of the interference the wire causes on the sensor, even with a PWM based dimmer, make sure you only heat the wire between frames and not during capture or you will get horizontal banding due to interference.

Also a word of caution about those led dimmers, they switch at a fairly high voltage, personally I found them a bit to agressive for the heating element, it's too much heat output even set to a minimum, and if you are not carefull you can melt the sensor frame quite easily!

What I use is a voltage regulator set to minimum, it's safe as it's set and forget and it delivers a very steady warm to your nichrome wire

Here's the link:

http://www.ebay.com/itm/10-pcs-DC-DC-LM2596-Step-Down-Adjustable-Converter-Power-Supply-Module1-3V-35V-/130984316514?pt=LH_DefaultDomain_0&hash=item1e7f460e62

Yes, I bought ten of these as they are sooooo cheap crazy thing, I heard you can also power up your DSLR from one of these, just set the desired voltage with a mutimeter, connect to your 12V power supply and battery adaptor and off you go.

Cheers,

Luís

[libraryman]

Hi Luis thanks for your post, your opinion is much appreciated, I had wondered about putting the nichrome into that groove, however it is not easy as you must appreciate, so fitted it without the fine bore shrink tube further out in the frame, have you put in some kind of timer to apply heat only between capture?

I had not appreciated appreciated the possibility of interference on the sensor!

Ray