Quick Question - cable management, power and my dew controller
Hi All,
I am in the process of lifting the majority of cabling (CCD, Filter wheel, autofocuser, usb hub, dew heater) off the ground to reduce tangle etc.
So far so good and happy with the results.
I have a bit of a sticking point though when it comes to the dew heater. It is rated to 7 amps up to a max of 15 (DigiFire 8 for those interested). The heater has an internal self-resetting fuse should it go over and it is designed to run on 7 amps with a cig lighter plug or 15amps if you change to something like an Anderson plug arrangement.
I have a powerwerx Anderson pole (8 points) rated at 30 amps which is plenty for what I need.
I grabbed a fifteen amp extension lead on a reel and rewired the three pin plug to an Anderson plug so I can run the rig off my dual batteries in my 4x4. The reel portion has four three-pin plugs build in with an on and off switch and in build reset fuse.
I made up a three pin plug on the end of my mount power (AZ-EQ6 GT) so it plugs into one of the reel plugs (works a treat).
I have also made up a lead from the Powerwerx pole to go to another of the reel plugs(also works a treat).
My issue is I am not sure about the dew controller. 7 - 15 amps is a fair whack and I don't want to fry my gear.
Ideally, I would like the led from the power pole to include the dew controller rather than having to wire all separately etc.
I should add, when at home, I have a 16amp 240V to 12V transformer and would like to see if I can still minimise cabling by only having the one cable like my portable set up.
Has anyone else done something like this and how did it go? Also, if I use a 15amp lead from the OTA to the reel with a 10amp plug (ie standard not the 15amp caravan plug) should it be ok or will go on a slow cook.
Pete
Last edited by LaughingBeagles; 20-03-2018 at 08:37 AM.
Once you have everything connected run the heater on max. and test the voltage at the heater. It should be 11-12V.
While your at it, check all the 12v systems.
If the extension cable is too long, there may be a voltage drop.
If you are getting voltage drop, either shorten the cable or use 6mm cable designed for 12v systems (and then 240v 3 pin plugs won't work, you can't get the cable in).
Digifire might be ok if your using your gear in the middle of a Canadian winter but it is total over kill for Australian conditions. A cheap two channel Kendricks heater controller draws only 6 amps max, and even cheaper diy PWM controllers work just as well.
BTW, running DC current through reel units builds up heat in the cable reel very quickly.
I've seen a number of arduino and Raspi based PWM dew heater controllers that you can build for under $70AUD
Raspi would be overkill unless you want a web interface.
Essentially its a MOSFET controlled by a PWM pin to pulse the 12v. A few lines of code to read 1 or more temp probes and then adjust the PWM output rate accordingly. The soldering work is minimal and the most expensive part is the box and some Anderson/RCA connectors.
The DIY means you can pick a box that suits your shape and size needs.
