You can't use transformers to change DC voltage. They only work on AC.
However you can use a voltage regulator (to go down) or a voltage converter (to go up.)
From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, November 22, 2014 6:59 AM
Subject: Re: [ap-gto] Re: Power cable management
Just a 12v to 5v dc transformer.
There are some great suggestions in this thread for power management. I would also appreciate a recommendation on a 12v to 5v converter. I have two devices that require a power conversion, my camera and my rotator. George pointed out that there are thousands of converters out there and he shows one in his configuration. What are the one or two commercial "reliable" converters?
I attach my Kendrick dew heater and Starlight instruments Focus Boss II dual focuser controller to two custom made aluminum plates that I bolt to my AP 15" sliding bar on each side of the my TV NP127is. For solar, I mount my Lunt LS80T/PT solar scope piggy back on top of the NP127is using a home made mounting bracket. For night work I take off the Lunt and mount my finder and guide scope on the TV 5" rings. I attach the controllers to the aluminum plates using industrial grade Velcro sheets which you can cut to shape and stick on the plates with it's own self sticking adhesive. I put all my cables into cable looms with the appropriate cables exiting the loom at appropriate points to run to the various devices. I use cigarette plugs attached to the underside of the plates with the industrial velcro to hold the power supply cables feeding the dew heater and focuser controllers. I have a 7 port powered USB hub mounted between the forks on my AP900 to operate my SX camera, SX filter wheel, mount, Focus Boss focuser controller and the Orion Starshoot autoguider. I have a single 65ft powered usb cable running from the hub at the mount to my computer. For a power supply, I have my two power supplies (Alinco DM3300 30amp and Pyramid 5amp) as well as a 7 plug power bar mounted in a Stanley tool box. All cables are labeled for quick set up in the dark. When I am done, I unplugs the individual power and USB cables, roll up the cable harness and stuff it in the tool box on top of the power supplies. The power supply end of the cables stay permanently attached to the 110V and 12V power supplies. I use a heavy duty Velcro strip to hold the scope end of the cable loom to the scope. I have no problem with this harness getting caught on anything. I can set up and tear down in under 30 min.
It doesn't show all the details but will give you an idea.
The velco is a clever solution! I was wondering how to attach everything to a plate.