Is this a way to step down DC Voltage?

If i have a 12 volt supply, and would like a 9 volt supply, would there be any problems with connecting a 3 volt battery backwards to cancle out 3 of the volts leaving me with 9?
If that is possible, will the battery be run down. image to explain. http://img7.imageshack.us/img7/407/testcircuit.jpg?

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dilandou7 years ago
Forcing a reverse polarity charge through, for example, an alkaline battery can cause it to overheat, causing a gas buildup inside the battery, leading to swelling and possible explosion, or at least leaking of electrolyte.
dilandou7 years ago
Nooo, don't do that. :) You'll need to make a voltage divider or use a voltage regulator circuit. There are a good few instructables for power supply circuits. Give it a search.

Could anybody tell me how can I step down a high voltage dc to a low voltage dc. I found in nets that upto 36V DC can be step down to 5-10V. But I want to step down 800V DC to 36V DC. Is there any circuits or any other devices to do this. Is it possible and safety to do this by means of voltage divider circuits.

You'd most likely need to look into switched mode dc to dc conversion. Here's an example of a 400 VDC to 12 VDC circuit: http://www.electroniq.net/power-supply/dc-dc-converters/top265kg-12-v-switching-power-supply-circuit-diagram.html
saberwing7 years ago
wow, where did you find that? just back away slwly. use a resistor to step down the voltage 
Dr.Bill7 years ago
How bout an adjustable voltage regulator circuit ?
try use a 9v zener diode, couldnt be simplier, connect the diode after the 12v battery and it will be regulated to 9v!!! cm
evildoctorbluetooth (author) 7 years ago
I know i can use regulator circuits, but i would like an explanation why i cant use the above circuit as a solution. only my parents are allowed to say no without an explanation behind it. ;-). and i would never use a voltage divider, the load regulation is diabolical.
lemonie7 years ago
No, no. Use a voltage regulator or tell us some more about it for an easier fix?