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Simple Question - 12VDC to 9VDC

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SoCalMacDude

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I have a 12VDC supply, need to power a 9VDC device.

Can I just use a couple of resistors to split the voltage?

If so, what values, if not, how can I achieve this?

Thanks!
 

you can use resistors but it's very not recommanded becuase the ouput voltage will be function of the current that your device require.

it's depend what is your application.

the best way is to use regolator.

you should first know how much current your device consume.

the output voltage of the regulator is fixed even if the 12V will not be fixed and if the current will not be fixed too.

you can find good regolators on Linear Systems site:

for 300mA: https://www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1040,C1055,P1378

for 3A: https://www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1040,C1055,P1820

for all others:
https://www.linear.com/pc/categoryP...40,C1055&action=sort&sortColumn=2&sortOrder=0

if you need any more help let me know

please pressed the "Helped" button
 

It is to power a small cheap audio amplifier to amplify some DTMF tones for decoding. I have 12V readily available, and the device normally uses a 9V battery, so current is low, and accuracy and stability is flexible. I would rather not get too fancy with it, just quick & dirty should do! Plus, I need 9V, not 3.3! :)
 

use a lm317 variable regulator....by changing the value of pot u can vary it from 3v to 9v
www.fairchildsemi.com/ds/LM/LM317.pdf

check the pins it is not the same as 7809 or 7805

or u can use a simple resistor and a 9v zener diode.....
or use two resistor divider
 

using resistors will just be a waste of energy........ur battery will drain faster........best solution is to use d 7809 ic as described above by carrier
 

Is it possible that the device already has a regulator on it since it's using a battery, and that the regulator may be able to handle 12 volts as well?
 

One other option is to connect 3 general purpose silicone diodes in series .. they will drop ≈2.5V ..
This solution should work fine .. simple and reliable ..

Regards,
IanP
 

good idea ianp this will definetly work,

I am using same technique, it is working.

--babesh
 

Now THAT's an innovative idea! I love it!!
. . . and I have diodes!
 

nice but it also acts like resistor and dissipates energy.....not so energy efficient at high current.....
 

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