the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
icon

12v converted to 6volts. how to do?


Post ReplyPost New Topic
< Prev Topic Next Topic >
dudek38 
Copper - Posts: 250
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: March 28, 2004
Location: United States
Posted: November 11, 2004 at 9:32 PM / IP Logged  
lets say we have a mobile electronic product that uses 6volts from a cig lighter plug that id like to hardwire. im sure there is a resistor in the cig plug. how do i put a resistor inline to drop the volts?
owner of
Motion Marine & Car Audio
the florida keys
drvnbysound 
Silver - Posts: 289
Silver spacespace
Joined: May 06, 2002
Location: United States
Posted: November 11, 2004 at 10:43 PM / IP Logged  
What kinda current draw is the load device going to be drawing? This will need to be determined before selecting a resistor because if you just pick a resistor you may end up burning it up by using it over its power rating.
Similar to the way speaker impedances work. If you have a 12V source, you will need a series resistor of the same value of the load (whatever you are powering).
When you have a series circuit, the voltage across each load will add up to the input voltage. Thus, if you have 3 resistors in series with a 12V source, they will drop a total of 12V. If you have 2 resistors, of the same value, each will drop equal voltage, thus 6V each. Therefore, if you select a resistor with the same impedance as your load, you will be able to drop 6V across your load.
WOW. ENOUGH SAID. I am working on a BS degree in Electrical Engineering. Actually working on designing a small 5-band EQ as a project for one of my classes this semister, how fun. Let me know if you have any other technical questions.
For quickest response, e-mail me @ drvnbysound@aol.com
russ lund 
Copper - Posts: 188
Copper spacespace
Joined: April 07, 2004
Location: United States
Posted: November 13, 2004 at 9:39 AM / IP Logged  
Let  us know the current your device will need.You might be able to use a resistor and a zenner diode for a regulator.Or use a NTE 962 or 1962 3 terminal regulator ic(simple).Russ
BigDog
dudek38 
Copper - Posts: 250
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: March 28, 2004
Location: United States
Posted: November 13, 2004 at 7:59 PM / IP Logged  
a mechanic friend of mine has a kit that will test the draw of the unit and determine the size resistor. i thought this subject would be fairly simple, but its very complex. i was thinking i could just solder a resistor inline with the power wire. i undestand i must use the right size resitor to make sure i have enough and no too much power. what does a simple resistor look like? where does one but them? blah blah blah...
owner of
Motion Marine & Car Audio
the florida keys
Mad Scientists 
Silver - Posts: 380
Silver spacespace
Joined: February 07, 2004
Location: United States
Posted: November 14, 2004 at 8:45 AM / IP Logged  

dudek38 wrote:
a mechanic friend of mine has a kit that will test the draw of the unit and determine the size resistor.

 Measure the draw of the unit with an ammeter then use Ohm's Law.

 Item draws 150ma.. needs 6 volts..

 Resistance = volts divided by amps

?=6/.150

R= 40 ohms

 To find wattage of the resistor, multiply amps times voltage..

Watts = 6 volts * .150 amps

Watts =  0.9 - use a 1 watt resistor.

 Personally, I'd just use an adjustable voltage regulator.. It depends on what the device is, but using a voltage divider circuit with resistors usually isn't the best way in terms of voltage regulation..

 For parts, I use Digikey, Jameco, JDR Microdevices, and when I need something right now, Radio Shack. Unfortunately, Rat Shack will be the most expensive, and the people behind the counter won't have a clue about electronic components.

 Regards,

 Jim

dragonrage 
Copper - Posts: 193
Copper spacespace
Joined: March 15, 2003
Location: United States
Posted: November 14, 2004 at 5:22 PM / IP Logged  
You can't use a voltage divider, because the resistance needed will change with the load hooked up. Use a regulator.
2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?
haemphyst 
Platinum - Posts: 5,054
Platinum spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: November 14, 2004 at 5:56 PM / IP Logged  
Yes, the regulator is the easiest way to do it. If you buy a three terminal fixed regulator, the most common being a 78xx with the xx being the desired fixed output voltage (and that's an industry standard number to cross reference) your installation is as simple and straight-forward as you can get. See the diagram below:
12v converted to 6volts. how to do? -- posted image.
You can order this device pretty much any place they sell electronics components - should run about 4 dollars. The best part of this type of installation, is you need to do NO figuring, no math, no construction... it is a simple point to point device, with regulation. This means that whether you car is running or off (14.4/2 = 7.7 volts or a 28.3% OVERVOLTAGE if you use a simple voltage divider - BAAAAAD) and no matter what the load is (up to the safe operating load of the device) you will ALWAYS get just exactly 6 volts...
I would have thought a BS in Electronics would have known about simple three terminal fixed regulators... (jab - poke - jab) 12v converted to 6volts. how to do? -- posted image.
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
dragonrage 
Copper - Posts: 193
Copper spacespace
Joined: March 15, 2003
Location: United States
Posted: November 14, 2004 at 6:20 PM / IP Logged  
Order from www.mouser.com btw, and if you need more than 1.5A, you can well, find a regulator that does support more, or you can put regs in parallel for (Current each will take) * (Amount of regulators)
2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?

Sorry, you can NOT post a reply.
This topic is closed.

  Printable version Printable version Post ReplyPost New Topic
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

  •  
Search the12volt.com
Follow the12volt.com Follow the12volt.com on Facebook
Friday, March 29, 2024 • Copyright © 1999-2024 the12volt.com, All Rights Reserved Privacy Policy & Use of Cookies
Disclaimer: *All information on this site ( the12volt.com ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information.

Secured by Sectigo
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
Support the12volt.com
Top
the12volt.com spacer
the12volt.com spacer