Dark Sensor on a Breadboard
I use it with an Ultra High Brightness Blue LED (10mm), available from Radio Shack.
That produces enough light to navigate through a room at night, without turning on any other lights.
With a minor modification, it can be used with 4 AA NiMH batteries (4V to 5.6V), although the specifications call for 6V. It has been working very well for me. Other schematics for 6 volt and (only) one transistor variations are available from the buildcircuit.com web site.
In order to use the circuit with 4 AA batteries, just bump up the resistors to all be 1K Ohms.
The 4 AA NiMH batteries last about a few days, so I have found it useful to add a low voltage indicator.
|Dark Sensor on a Breadboard from http://www.buildcircuit.com/dark-sensor-on-breadboard/|
Low Battery Indicator Using Two Transistors
A nice low battery indicator circuit is available here:
Conveniently, this circuit provides a low voltage circuit that works well with the above automatic night light, using 4 AA NiMH batteries.
It has an adjustable preset (roughly, a 50K potentiometer), which can be set for a variable number of batteries.
The web page also includes instructions for reversing the circuit to use it as a high battery indicator. The high battery indicator could be useful of you also charge the AA NiMH batteries.
Another one of my favorites from Mr. Swagatam Majumdar.
|Low Battery Indicator Using Two Transistors from Homemafe Circuits Just For You|