Building a power inverter
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=68809
Printed Date: May 02, 2024 at 2:39 AM
Topic: Building a power inverter
Posted By: j_darling2007
Subject: Building a power inverter
Date Posted: December 20, 2005 at 2:40 PM
Does anyone have a schematic for a 12vdc to 120vac power inverter. I would like to build one, but don't know how. How much money would I save, and is it worth it to you all to go through all the trouble to build one.
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There are 3 kinds of people in the world, those who can count and those who can't
Replies:
Posted By: haemphyst
Date Posted: December 20, 2005 at 3:26 PM
j_darling2007 wrote:
Does anyone have a schematic for a 12vdc to 120vac power inverter.
How big an inverter do you need?
j_darling2007 wrote:
I would like to build one, but don't know how.
This statement makes me think it might be worth your time running to Kragen and picking one up off the shelf...
j_darling2007 wrote:
How much money would I save, and is it worth it to you all to go through all the trouble to build one.
Probably none, unless you were building a HUGE one - several thousand watts or better. Manufacturers got us ALL beat when it comes to buying up the parts for cheap... Considering you can buy a 300 or so watter for less than 50 bucks now, it is probably not worth your time... Now, if you were looking for a good project, buy the one you want, and figure a way to integrate 120v throughout your car, so passengers can just "plug in"... ------------- 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."
Posted By: j_darling2007
Date Posted: December 20, 2005 at 3:49 PM
Let me clarify myself. I know how to solder a circuit board, etc, I just don't know how to build a power inverter. I want to run my PS2 on the inverter, so I don't know how much watts for sure. I'll check when I get home. And I was thinking. To run say, 5 amps at 120vac, I would need to supply 50 amps at 12vdc, right. I know it works like this for dc to dc, but is it the same from dc to ac. That would be an awesome project, though, I might try to do something like that eventually. Thanks alot for the help. Schematic, anyone??? ------------- There are 3 kinds of people in the world, those who can count and those who can't
Posted By: haemphyst
Date Posted: December 20, 2005 at 4:06 PM
https://www.aaroncake.net/circuits/inverter.htm
https://www.technology.niagarac.on.ca/people/mcsele/i2k.htm
https://www.interq.or.jp/japan/se-inoue/e_ckt8.htm
https://www.interq.or.jp/japan/se-inoue/e_ckt30.htm
https://www.discovercircuits.com/C/co-dctoac.htm
https://www.repairfaq.org/sam/samschem.htm
I appreciate the fact that you want to do it yourself, but I think you are going to find it will not be worth your time...
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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."
Posted By: mobile1
Date Posted: December 20, 2005 at 4:07 PM
for a ps2, you can just use a 300 watt inverter and it would cost around 30 - 50 bucks. WAAYYYYY cheaper that building your own.
Posted By: j_darling2007
Date Posted: December 20, 2005 at 4:58 PM
Thanks for the links and help. I kind of want to build one just for the sake of doing it. Depends on how much it costs and how hard it is. j_darling2007 wrote:
To run say, 5 amps at 120vac, I would need to supply 50 amps at 12vdc, right. I know it works like this for dc to dc, but is it the same from dc to ac.
Is this right?? ------------- There are 3 kinds of people in the world, those who can count and those who can't
Posted By: haemphyst
Date Posted: December 20, 2005 at 5:57 PM
50A plus heat wasted to inefficiencies. A typical inverter runs aroun 80% eficient, (theoretical maximum efficiency os 92%) so add an additional 12.5A to be blown off in heat...
And actually, 120v is around 180v pk-pk, so you could get around 3.5A RMS from 50A in...
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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."
Posted By: menace2sobriety
Date Posted: December 20, 2005 at 9:16 PM
ps2 is 9volts dc so all you would have to do is drop the power down, but that will mean having to wire it after the transformer which means opening the unit up.
Posted By: Slammed_Am
Date Posted: December 21, 2005 at 10:52 AM
the PS2 actually opperate off 12V at least the older ones do, not sure about the slim ones.
With the older ones you haveto dismantle it thus voiding its warranty, butall you have to do is solder 2 wires(+ and -) to the board hook it up like any other 12v accessory and voila.
Posted By: Jay T
Date Posted: December 21, 2005 at 9:35 PM
Quick question..... do the inverters we buy for our vehicles use Pulse Width Modulation for the DC to AC? or is the circuitry dependent on the quality / cost
Posted By: j_darling2007
Date Posted: December 21, 2005 at 9:44 PM
Yeah, its the old school PS2. But even if it ran at 9 volt, I would just have to add a resistor to the circuit, how many ohm would the resistor have to be to drop the voltage to 9 volts.
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There are 3 kinds of people in the world, those who can count and those who can't
Posted By: geepherder
Date Posted: December 22, 2005 at 8:01 AM
It's not that simple since the load on the ps2 would be constantly changing. Check to see if it runs on 12 volts as suggested before.
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My ex once told me I have a perfect face for radio.
Posted By: haemphyst
Date Posted: December 22, 2005 at 12:53 PM
Jay T] wrote:
Quick question.....
do the inverters we buy for our vehicles use Pulse Width Modulation for the DC to AC? or is the circuitry dependent on the quality / cost
Yes. Nearly all inverters run usimg the PWM method of conversion. I say nearly all, because if I say "all", someone will call me, and I can't say for CERTAIN that they do all run this way... The frequency of the pulses varies in more expensive units, and as you move closer to a true sine-wave inverter (the most expensive ones), your pulse frequency will be higest of all the types. Nearly all of the inexpensive inverters you will buy today are either square wave or modified-sine wave inverters, and can VERY EASILY contribute noise to an AC powered system running in a 12VDC environment, especially if interconnected to the 12 volt accessories.
j_darling2007 wrote:
Yeah, its the old school PS2. But even if it ran at 9 volt, I would just have to add a resistor to the circuit, how many ohm would the resistor have to be to drop the voltage to 9 volts.
WRONG. A simple resistor would work, but it would be a bad idea. If you know the CONTINUOUS current requirements of the device, you can pick a fixed-value resistor. While geepherder (below) is correct, it is not going to change THAT much. A fixed resistor will give one voltage at engine-off battery voltages, and another (higher) at engine-running battery voltage. A much better solution would be a three-terminal fixed voltage Voltage regulator. Do a search on the 'net for "7909 voltage regulator". Put 4 in parallel on a circuit board, and be done with it. 4 of them will give you 4A of continuous output current, regardless of the input voltage from 9 to 37 VDC - seems MADE for automotive applications, doesn't it?. If you were to add heatsinks, you could have as much as 6A of current. If your game machine runs from 12 VDC, search for a 7912 three-terminal voltage regulator.
geepherder wrote:
It's not that simple since the load on the ps2 would be constantly changing. Check to see if it runs on 12 volts as suggested before.
(see above) ------------- 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."
Posted By: Ween
Date Posted: December 22, 2005 at 3:02 PM
hi, might a LM338 (5A) or LM350 (3A) with a few resistors be just as easy...one part, no parallelling needed. and you'd need to dissipate about 20 watts of heat, worse case. are the part numbers 79xx or 78xx, negative or positive ? mark
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