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  • Regulating Car's Voltage to 12 Volts

    Ok, I've tried twice to come with a circuit that will regulate a cars voltage to 12 volts. Reason being, I bought one of the cheaper 200 watt unregulated power supplies and an ITPS and am now in a bad position. As far as I can tell nobody offers circuits for this task that cost less than $70 so I am asking for help. If you have any idea on how to build a regulator circuit that can handle between 10 and 20 amps I'd appreciate your input. I have looked into both Linear and Switching Regulators and from what I see both of them would require that I first boost the voltage to around 20-25V DC and then scale it down. I am not looking for a unit that can survive cranking, however after I turn my car off, it has to be able to output 12 volts so that the computer won't crash instead of gracefully shutting down. The simpler and cheaper the circuit the better, but at this point I'll take just about anything I can get. Thanks.

  • #2
    It's probably not what you want to hear, but I suggest doing a cost/benefit analysis and determining whether or not it you might save by just buying an Opus. Remember, it's not just money, it's also time. If skipping the Opus means that 6 months from now you still won't have a reliable working system, the extra money up front might be worth it.
    Chrysler 300 - Fabricating
    http://hallert.net/

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    • #3
      Originally posted by Chairboy
      It's probably not what you want to hear, but I suggest doing a cost/benefit analysis and determining whether or not it you might save by just buying an Opus. Remember, it's not just money, it's also time. If skipping the Opus means that 6 months from now you still won't have a reliable working system, the extra money up front might be worth it.
      Yeah I know, if I hadn't already spent $90 I'd be all over the Opus, however unfortunately I have and I just can't imagine spending around $280 just to get the power working for my carputer. One idea that I have, that would take some work to get it properly working is to use an inverter and a regular atx power supply which would provide power to my ITPS and DC-DC powersupply. I realize this would run into a lot of problems as a result so it's my LAST option.

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      • #4
        I must be missing something. The ITPS is a regulator. If you put it in line before the 200 watt power supply, it should regulate the power to 12 volts.

        Not sure if it can handle 200 watts, but it handles my 120 watt supply okay - after I put a fan on the heat sink to keep it cool.
        Originally posted by ghettocruzer
        I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
        Want to:
        -Find out about the new iBug iPad install?
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        • #5
          the older itps' can only handle 60w of power, the newer ones i believe can handle a little more? either way its a waste using a 120w PSU with an itps, you arent reaching your power supplys full potential, but hey if it works, dont change it!
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          • #6
            ohh and putting a fan on the heatsink probably means it can also handle more too
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            • #7
              Triwav,

              One thing you may want to consider is taking another look at the CarNetix P1260 regulator. You could keep your "200 Watt" PSU and put the P1260 in place of the ITPS. It has similar functionality, but actually works! It will provide up to 60 watts of power to your PSU, but that's really all the regulated power your "200 Watt" psu can provide (see this artice on our website . The "200W" is vendor B).
              And, you'll get the added benefit if surviving crank, remote enable for your audio amps, and pulse-start from a remtoe wireless device.

              MP3Cars.com store will have these P1260s in stock soon...

              Let me know if you have any other questions. Or visit our support forum .

              Enjoy!
              MikeH

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              • #8
                Originally posted by MikeH
                Triwav,

                One thing you may want to consider is taking another look at the CarNetix P1260 regulator. You could keep your "200 Watt" PSU and put the P1260 in place of the ITPS. It has similar functionality, but actually works! It will provide up to 60 watts of power to your PSU, but that's really all the regulated power your "200 Watt" psu can provide (see this artice on our website . The "200W" is vendor B).
                And, you'll get the added benefit if surviving crank, remote enable for your audio amps, and pulse-start from a remtoe wireless device.

                MP3Cars.com store will have these P1260s in stock soon...

                Let me know if you have any other questions. Or visit our support forum .

                Enjoy!
                I'm afraid 60 watts will not be enough, I guess I should of explained my setup. I'm using a duron 700 with a microatx board um. 256 Ram 3.5" 5400 RPM system hard drive and will have either a 60GB or 80GB external 2.5" drive for all my mp3's. I will eventually be using an all in wonder card in order to receive fm radio. I'm also going to have a full size dvd drive along with several USB devices. When I did my calculations, I came out to around 123 watts which is obviously just an estimate but well over 60 watts. What I am really looking for here is somebody who has succesfully designed a circuit specifically for regulating the cars voltage to 12 volts AND can provide between 10 and 20 amps. Oh yeah, one more thing. I'm pretty sure they shouldn't draw a lot of power but I am also going be using the power supplies 5V channel to run REM for my two amps JBL BP1200.1 for my subs and a cheaper four channel JBL amp for my component speakers. I will also have to run one to the powered antenna so it will go up and down when I turn the computer on and off. Thanks for all your help people.

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                • #9
                  triwav,

                  You're right. With that type of power requirement you'll certainly be over the 60 watt limit. In fact your "200W" psu will also choke since it's regulated output is only 60 watts. Here's the spec of its rails. Sorry the 2 figures don't line up...
                  Attached Files
                  MikeH

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                  • #10
                    Originally posted by MikeH
                    triwav,

                    You're right. With that type of power requirement you'll certainly be over the 60 watt limit. In fact your "200W" psu will also choke since it's regulated output is only 60 watts. Here's the spec of its rails. Sorry the 2 figures don't line up...
                    That is true, that is why I need a regulator so that I can make use of the other 140 or so watts of power coming out of the 12 volt rail. I know that it will work properly because I have used the system without the ITPS in my house with a AC-DC ATX powersupply running my DC-DC 200 watt power supply off the 12 volt rail of the ATX power supply. So it does provide 200 watts, it's just not 200 watts regulated.

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                    • #11
                      Ok, I've been thinking. I've decided that the Inverter-AC Power Supply thing just wouldn't work. What I am thinking now is one of two things. First, I was thinking of possibly just buying a second ITPS giving me at least 120 watts, if not more which "should" be able to handle the load I'm putting on it. My other option is this. I just some free samples from national.com for these http://www.national.com/ds/LM/LM1577.pdf they are step-up regulators which means they theoretically should be able to withstand an engine start. Any ideas on whether these would work well for my situation. I don't see why not. They don't have the high input voltage requirement that the linear and regular switching regulators required but I don't know this stuff too well. Also I obviously would need use multiple units, I ordered 5. With Linear I know that you have use resistors on the regulated positive outputs to prevent them from overloading. Is that the case with these as well thanks.

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                      • #12
                        I do not think they will work because the input is tied to the ouput through an inductor and diode. As the input approches +12.6 volts, the output will start tracking the input. You would have to have a buck converter in front of this chip that will cut the input to a lower voltage than the ouput. Just my opinion though.

                        Walt
                        Walts DC DC ATX Power Supply

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                        • #13
                          Originally posted by waltsongs
                          I do not think they will work because the input is tied to the ouput through an inductor and diode. As the input approches +12.6 volts, the output will start tracking the input. You would have to have a buck converter in front of this chip that will cut the input to a lower voltage than the ouput. Just my opinion though.

                          Walt
                          Ok thanks for your help, so it looks like it's down to either buying another ITPS or other regulating unit and hooking them up in parallel. This should work right? Thanks.

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                          • #14
                            Connecting several switching regulators in parrallel may or may not work. I've never tried it. I found out recently that you can not parrallel an NTE1954 (low drop-out 12 volt regulator) with an LM7812 (standard linear regulator). The 7812 overheats and burns up. Not sure why, but it does not work. As long as both regulators are the same, it may be okay.

                            Best of luck
                            Walt
                            Walts DC DC ATX Power Supply

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                            • #15
                              Originally posted by waltsongs
                              Connecting several switching regulators in parrallel may or may not work. I've never tried it. I found out recently that you can not parrallel an NTE1954 (low drop-out 12 volt regulator) with an LM7812 (standard linear regulator). The 7812 overheats and burns up. Not sure why, but it does not work. As long as both regulators are the same, it may be okay.

                              Best of luck
                              Walt
                              I am assuming that is because of different resistance (the electrons took the easiest path) that's what I'm wondering in this case. Whether they will have the same resistance or if it even matters. If it does matter, what resistors should I use. Links would be nice. thanks

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