The 3.85V 1.2 A KPR139 Tx mentions works very well in a 4AA-cell NiMH configuration in addition to a 3 C or D cell Alkaline configuration. KPR139's can also be purchased at $1.41 @ plus shipping from www.topbulb.com.
As an Amazon Associate we earn from qualifying purchases. Product prices and availability are accurate as of the date/time indicated and are subject to change.
Ya know there is an interesting looking 3 AA light at my local Auto Zone, $3 a pop. If anyone is interested...your Auto Zone might have them too, they're up by the register in little clear buckets at mine...