3vdc power distribution controller

[pomprocker]

i have a bunch of wireless contact closure sensors and motion sensors around the house. Unfortunately they each use two AAA batteries, and with the motion sensors they loose their settings when the batteries are removed. I want to replace the batteries with a power supply. Somebody recommended a wooden dowel and using a bunch of cheap 3vdc wal warts, however that did not sound appealing.

What I had in mind was running a pair of small gauge wires from each sensor up into the attic somewhere where they are each connected to one circuit that gives each one of them 3vdc and the amperage they need. Then I only need 1 wall-wart that I can plug into the circuit and an outlet some where near the attic entrance.

Changing batteries and reprogramming sensors once a year has a low family approval rating.

[madsci1016]

If you are willing to run the wires, go for it.

However, a tweak to your plan:

You can't really run 3V across your 'distribution system' as when the power goes from source to load it will drop voltage really quickly. You would have to run a higher voltage, at least 12V, preferably higher, and add a voltage regulator at each sensor to drop the 'high voltage' down to 3V. This will make up for the voltage drop along long runs of wire.

[waltr]

I was going to suggest running a higher voltage on the distribution wires then a reg at each module but madsci beat me to it.

Just for some ideas:
Check out the low-voltage lighting next time you're at the home improvement store.
The two other low voltage systems you probably have in your house are the thermostats and the doorbell.

[pomprocker]

Ok so wired would be ugly and doesnt sound to appealing.  Somebody on another forum mentioned adding caps to the motion sensors so they still have a little juice while your changing batteries....

Anyone have any capacitors in mind to sustain 3vdc for a minute or so?

[madsci1016]

You tell use current draw for an answer to that question properly. But my wild guess would be BIGGGGG Caps.

[hopslink]

You could just add cheap connectors to each sensor so you can connect another battery in parallel while swapping out.

[Razor Concepts]

Use supercapacitors, cheap small and should work well.

[pomprocker]

Use supercapacitors, cheap small and should work well.

Thats what i was thinking, 1farad supercaps...