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110 to 12v converter?

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  • 110 to 12v converter?

    Hi all,
    Made a setup to power the table on my mill using a 12v automotive wiper motor. I'm now running it through a motorcycle battery with a battery tender (charger). Would like a more permanent/neater solution. Been looking at converters and would like at least 20amp rating. The speed controller is 20a and the motor is rated for 15a. Any suggestions?

  • #2
    Lots of stuff available - like this : http://www.ebay.com/itm/110V-120V-22...item563ab5328f

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    • #3
      Hey lidz .. what kind of controller ?
      John Titor, when are you.

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      • #4
        Originally posted by mikeamick View Post
        Hey lidz .. what kind of controller ?
        Cheap Chinese one. Ebay.

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        • #5
          Electrolytic caps will age and lose value, but this happens quicker and will have worse results in a switching power supply vs a 'brute force' transformer/rectifier/filter. Largely for this reason I stay with the traditional approach when I build a power supply that I want to last. The capacity value needs to be much larger at 60 hz than at some high switching frequency, but the cost isn't really much greater. The transformer based 60 hz power supply will be heavier and larger, but what would that matter- and dc motors don't much care if there's some ripple on the output voltage. As well, they are capable of delivering a higher than normal current for short periods, and don't have any mysterious shut-down characteristics that a switching power supply might have.

          Any controller you find will likely be a pulse width modulator of some sort, and will work fine with this.

          12V power supplies are made for car audio displays, and come in various current ratings. Something capable of 20 amps would be a relative lightweight. The newest ones are likely to be switching power supplies, but you might be able to find an older one for cheap. They are likely to be regulated as well, which might serve you well in some future applications, if not now. I don't think you really need regulation if you're working through a controller anyway.

          You might even find a basic battery charger that would serve, though for the most part these days they have mini-brains which might prevent them from outputting if they don't see a voltage to start with. You can bypass this, but you'll need some electronic knowledge to get the job done. If you find a charger that works, is heavy, and has the current capability, you can use that as the start of your power supply project. For the most part you'd only have to add an electrolytic filter cap.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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          • #6
            Most old junk campers have pretty nice converters in them to run the 12v lighting and water pump when on shore power, they can often be had for about nothing. I have one that runs a bunch of stuff in my shop, mine even has a built in battery charger that comes in handy.
            Anybody that thinks they know it all doesn’t even know enough to understand they know nothing!
            Andy

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            • #7
              You can find a junk desktop computer and remove to ATX power supply and build you a power unit cheap.
              I have some instructions on how to do it but cant attach them here. You can send me your e-mail if you like i will send them to you. Yes you can buy them on e-bay butdon'tt forget to look at the shipping cost
              Can you post a pic of your power feed
              Last edited by GEP; 01-03-2014, 07:28 AM.

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              • #8
                this is half the price, but they still are expensive, i mean thats only 360 watts.

                http://www.ebay.com/itm/110-220V-to-...ht_9651wt_1187

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                • #9
                  Did the same on my mill, and simply got a 12V transformer, bridge rectifier and some filter caps. Makes a nice 12V power supply with fairly steady DC. Then bought a PWM from China (about $4.00) as a speed control .... works great.

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                  • #10
                    Originally posted by Stern View Post
                    Did the same on my mill, and simply got a 12V transformer, bridge rectifier and some filter caps. Makes a nice 12V power supply with fairly steady DC.
                    12V through a bridge would be about 16V, yes?
                    Milton

                    "Accuracy is the sum total of your compensating mistakes."

                    "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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                    • #11
                      Originally posted by darryl View Post
                      Electrolytic caps will age and lose value, but this happens quicker and will have worse results in a switching power supply vs a 'brute force' transformer/rectifier/filter.
                      That depends largely on the design and component choice. A high quality switched mode power supply can last for decades. A cheap Chinese one might last a couple of years if you don't tax it too hard.



                      Ripple current and heat are what kills aluminum electrolytic capacitors. In switched mode power supplies, the ripple currents can be very large. With a "brute force" design, the ripple current tends to be much lower.

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                      • #12
                        Originally posted by GEP View Post
                        You can find a junk desktop computer and remove to ATX power supply and build you a power unit cheap.
                        I have some instructions on how to do it but cant attach them here. You can send me your e-mail if you like i will send them to you. Yes you can buy them on e-bay butdon'tt forget to look at the shipping cost
                        Can you post a pic of your power feed
                        Here's all the info from my blog-
                        http://www.blogger.com/blogger.g?blo...0;src=postname
                        Last edited by tricklidz; 01-03-2014, 01:26 PM.

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                        • #13
                          Originally posted by DICKEYBIRD View Post
                          12V through a bridge would be about 16V, yes?
                          A 12 volt peak input would result in an output that is 12V - 2*Vf where Vf is the forward voltage drop of the diodes. Typically values range from 0.7V to 1.5 volts per diode. If you measure RMS voltage, than you can convert that to Vp by multiplying by ~1.4 (or the square root of 2).

                          So, 12 Vrms = ~ 16.9 Vp. You then subtract the two diode drops. Lets assume a Vf of 1.2 volts. Then the output would be ~14.5 VDC.

                          Couple the 14.5V with a PWM controller meant for 12V and you'll never know the difference.

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                          • #14
                            Originally posted by tricklidz View Post
                            Updated blog with video
                            http://tricklidz.blogspot.com

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                            • #15
                              http://www.instructables.com/id/ATX-...op-Power-Supp/
                              Here is a ATX power supply conversion

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