Voltage Divider question - 6 from 12 Volts

Brit01 · 14th August 2009, 12:30 PM

Guys,

Can I use a simple voltage divider circuit to get 6 Volts out of a 12 volt transformer?
I have a secondary 12V at 4 Amps.

What would be suitable resistor values (and wattage) here to get 6 Volts at 2.5 amps min. from 12 volts? I want to supply a 6080 heater.

I found this great calculator:

http://www.educalc.net/876080.page

poynton · 14th August 2009, 01:34 PM

Big Resistor needed !!!!

To drop 6V at 2.5A requires 6 / 2.5 = 2.4ohms at 15watt rating

Get a 6v transformer - less heat and probably cheaper

Andy

wwenze · 14th August 2009, 01:43 PM

How about changing your circuit to two 6080s with the 12V feeding their heaters in series instead?

Brit01 · 14th August 2009, 01:44 PM

Thks Andy.

Thought it was going to take some heat.

Although I may be able to get some 20W resistors for about 2 USD here.

Iron is not cheap here. Let me find out.

Brit01 · 14th August 2009, 01:46 PM

Quote:

How about changing your circuit to two 6080s with the 12V feeding their heaters in series instead?

True. The other option I thought about.

If I've got 4 amps at 12V.

Then 2 x 2.5 amp heaters would be 5 amps.

But at 6 volts this would be ok yes?

Rafael L · 14th August 2009, 02:37 PM

with any value of resistor, you make a divisor EX 0.5 ohms + 0.5 ohms...
More the correct you use a Zener diode (1N5340)

Brit01 · 14th August 2009, 02:41 PM

Quote:

More the correct you use a Zener diode (1N5340)

sorry not sure what you mean.

A zener with each resistor? Or as a substitute to create the required resistance?

Rafael L · 14th August 2009, 03:06 PM

Quote:

Originally posted by Brit01

sorry not sure what you mean.

A zener with each resistor? Or as a substitute to create the required resistance?

You need not resitores, only one Zener diode, above 6 v leads, so does the voltage not exceed 6 v, look fig.
-his source is not symmetric, will need only one Zener diode....

pjp · 14th August 2009, 03:14 PM

Rafael.luc I hope you know what you're talking about... 1N5340 is a 5W part which can pass approx. 800mA ...

Brit01 · 14th August 2009, 03:22 PM

Quote:

1N5340 is a 5W part which can pass approx. 800mA .

yep. I need something they will be capable of handling 5 amps at least.

14th August 2009, 12:30 PM	#1
Brit01 diyAudio Member Join Date: Jul 2008	Voltage Divider question - 6 from 12 Volts Guys, Can I use a simple voltage divider circuit to get 6 Volts out of a 12 volt transformer? I have a secondary 12V at 4 Amps. What would be suitable resistor values (and wattage) here to get 6 Volts at 2.5 amps min. from 12 volts? I want to supply a 6080 heater. I found this great calculator: http://www.educalc.net/876080.page

14th August 2009, 01:34 PM	#2
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	Big Resistor needed !!!! To drop 6V at 2.5A requires 6 / 2.5 = 2.4ohms at 15watt rating Get a 6v transformer - less heat and probably cheaper Andy __________________ If it ain't broke, break it !! Then fix it again. It's called DIY !

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14th August 2009, 01:43 PM	#3
wwenze diyAudio Member Join Date: Mar 2008	How about changing your circuit to two 6080s with the 12V feeding their heaters in series instead?

14th August 2009, 01:44 PM	#4
Brit01 diyAudio Member Join Date: Jul 2008	Thks Andy. Thought it was going to take some heat. Although I may be able to get some 20W resistors for about 2 USD here. Iron is not cheap here. Let me find out.

14th August 2009, 02:37 PM	#6
Rafael L diyAudio Member Join Date: Nov 2008 Location: Brazil	with any value of resistor, you make a divisor EX 0.5 ohms + 0.5 ohms... More the correct you use a Zener diode (1N5340)

14th August 2009, 03:14 PM	#9
pjp diyAudio Member Join Date: Nov 2006 Location: under the rainclouds	Rafael.luc I hope you know what you're talking about... 1N5340 is a 5W part which can pass approx. 800mA ...

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