# Greetings all newbie needed guide :)

Discussion in 'General Electronics Chat' started by pudhiyavan, Nov 25, 2008.

1. ### pudhiyavan Thread Starter New Member

Nov 25, 2008
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0
Distributor (D) Needs to distribute 18W into two as 6W and 12W using the resistors. ref. http://www.allaboutcircuits.com/vol_6/chpt_3/5.html

Here i guess between the Source (S) and Battery (B) i need to have a charge controller so that the current cannot flow back to source. (still reading about Charge Controllers) can any one guide me please?

From B to L i need to controll the current, so can i use again resistors?

in all the above with a slight modification if i can go ahead can anyone tell me the K size's of resistors?

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2. ### beenthere Retired Moderator

Apr 20, 2004
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You can't really view it as distributing power. You supply the correct voltage to each load. Each load will take however much current it needs. A power dividing network is not called for.

The application of 12 volts to the fan is pretty simple, assuming it is a 12 volt fan. 12 watts is 12 volts and one amp, or 5 volts and 2.4 amps. That is not clear from the power requirement. Should the fan need 5 volts, you will have to use an active regulator to supply the correct voltage.

The other branch would be simple if it were only the LED's. A current limiting resistor might be all that was necessary. But a battery generally needs a charger and a source greater than its own voltage to force a charge on it. Batteries in like that one are usually for backup and isolated from the system with a diode so they only feed current to the circuit after a power failure.

3. ### pudhiyavan Thread Starter New Member

Nov 25, 2008
8
0
thanks beenthere..

"The application of 12 volts to the fan is pretty simple, assuming it is a 12 volt fan. 12 watts is 12 volts and one amp, or 5 volts and 2.4 amps. That is not clear from the power requirement. Should the fan need 5 volts, you will have to use an active regulator to supply the correct voltage"

here is the data copied from the fan's data sheet
VDC-VDC---------Amp--- Watt
12---4.0 to 13.2-- 0.95---11.40

"A current limiting resistor might be all that was necessary."

what could be the value of kohms is required? at the max the LED's will use 6w (around 140 LEDs)

"But a battery generally needs a charger and a source greater than its own voltage to force a charge on it
"

does it mean that 12x9 amps = 108Watt solar panel to be used? i guess i am writing a dumb query here, but still seeking your help to understand how it goes thru.

will start reading about diodes (if you can share some good documents for usage of diodes that will be help ful

4. ### beenthere Retired Moderator

Apr 20, 2004
15,808
295
A load takes the power it needs without forcing us to do more than supply the voltage it wants to operate with. So giving you fan 12 volts will make it happy. It will draw 950 ma with no further concern from us.