Dc voltage reduction in dry battery cell

I have designed a toy for my kid which runs on "C" size
dry battery cell however the size and shape constraints
have forced me to use a 9V battery instead.
I need someone to guide me on how I can limit the
voltage and current of this 9V battery cell to that of
a "C" battery cell.

Please advise!

 

[xray]

National semiconductors has several voltage regulators that take a higher voltage and reduce to a smaller voltage. The LM78XX series is a non adjustable voltage regulator, I'm not sure they reduce to 1.2 volts. The LM117/317 series is a three pin adjustable voltage regulator to 1.2 volts minimum. Depending on your load current 100mA to higher than 3A these devices can hadle it. Setting the output voltage only requies two resistors. A good look at the device and equations to make sense of the small circuit look at the following web page:

http://www.national.com/ads-cgi/viewer.pl/ds/LM/LM117.pdf.

If you need any further please let me know. drollinger@montana.net

 

[don01]

hi
xray has done a good job there on the small regulators which maybe the best way to go but as a suggestion late at night,- have a look in some of the battery or electronics catalogs for the less standard formats. you may even find the equivalent numbers in a rechargable or alkaline. One thing that springs to mind is the computer mother board batteries and photographic applications. Try Thomas register or eveready or duracell web sites.
good luck
Don

 

[jbartos]

Suggestion: In some cases, a suitably selected potentiometer could suffice. The more expensive items are dc-dc converters. However, these are more efficient than potentiometers and some regulators (especially, if you look at those resistors there and no efficiency posted).