# 9 Volts to 12 Volts DC to DC converter

Discussion in 'General Electronics Chat' started by haran, Apr 12, 2008.

1. ### haran Thread Starter Active Member

Apr 6, 2008
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i would like to know how to build a 9V to 12V dc to dc converter. I want to use a 9Volt battery as the voltage source(input).

2. ### hgmjr Moderator

Jan 28, 2005
9,030
214
What is the power consumed by the 12V load?

hgmjr

3. ### mrmeval Distinguished Member

Jun 30, 2006
833
2
http://www.national.com/appinfo/power/

Plug in the values and it will spit out the part you need. I came up with the LM25575 but I can't find the specs on the power output of a 9v battery so don't know how much power it can produce.

4. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
9v PP3 "transistor" batteries are pretty low-power devices, perhaps 150mAh

If the load was more than a few mA, the battery would get sucked flat pretty quick.

5. ### haran Thread Starter Active Member

Apr 6, 2008
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how do i calculate the power load for a circuit?

6. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
A X Hours = AH

What you need is a measurement of current your circuit requires from the 12V source, and we'll work from there.

7. ### haran Thread Starter Active Member

Apr 6, 2008
42
0
my circuit is using a 12 Volt input and the amp is below then 500mA

8. ### Audioguru New Member

Dec 20, 2007
9,411
896
If you make a voltage converter circuit that is 85% efficient and need 400mA at 12V then then 9V battery must supply 640mA.

A 9V alkaline battery's voltage drops quickly with such a heavy load. I have graphs from energizer.com and the highest current calculated is "only" 400mA.

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