User submitted Tutorial.
From Chuck Coleman.
Add a solar cell to the HawkEye and quit changing batteries !
These little guys are great, but batteries do go dead, and when you
change the batteries, the unit forgets its house/unit code and other
settings. But if the unit is outside, or in a sun-lit room, do it with Solar !
Here is a modification that you can do to all the MS sensors to keep the batteries fresh and at their maximum voltage.
You will need:
- 2 NiMH AAA batteries
- 1 Radio Shack #276-561a Zener Diode rated at 6.2 v 41 mA
- 1 Panasonic BP-376634 rated at 5.5v @ 30 mAh (Solarbotics.com part number SC3766)
- Some 22 gauge wire and solder
This hack is meant to work with the sensor being in a sunlit room for at least 3-4 hours a day. If you intend to do this on a sensor that will be in a darker room then you will need 2 solar cells and hook them up in series to get the higher voltage to keep the batteries charged at lower light levels.
I have found that with the following hack you can have the cells facing outside in bright shade and will generate enough voltage to keep the batteries charged.
This is by no means the end of this hack. There are all kinds of possibilities like running the wires outside and having the cells on the outside of the house for rooms that don’t have lots of natural light. Be creative. Don't let yourself get stuck by thinking you have to stay with the hack you see here.
Of course all liability is yours any time you start modifying a product. I can tell you that this hack works so well that I can actually charge dead batteries in the MS sensors that I have modified. It takes a few days but it does work. So keeping them charged is a piece of cake.
A word of warning. Be extremely careful in soldering the wires on to the tinned leads of the solar cell. If you keep the soldering iron on there to long it will remove the solder from the leads and ruin the cell.
Chuck Coleman
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Last modified: May 20, 2007
Michael Ferguson, webmaster@shed.com