transformer for 110v to DC 24v 1.3A

Discussion in 'The Projects Forum' started by salty joe, Dec 14, 2010.

  1. salty joe

    Thread Starter New Member

    Dec 14, 2010
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    I am looking for an economical transformer to run a DC water pump. If fairly simple, I'd love to assemble it.

    I need to buy a book for beginner electronics. I am only interested in DC stuff at this point.

    I suppose I better get a soldering iron too. This is for a hobby so I don't need the very best-but I don't want to waste money on junk. Any other specialty tools?

    Any reccomendations on these three points would be very much appreciated.

    Thanks,
    Joe
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Try Radio shack for the transformer,

    Get Basic Electronics by Bernard Grob.

    Get a 40W Soldering iron off ebay and some screw drivers, pliers, cutters, strippers, oscilloscope, pattern generator, flux core solders, hot gun, and some experience.

    Any thing else?
     
  3. tyblu

    Member

    Nov 29, 2010
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    you should be able to find many guides on winding your own transformer. Toroids look interesting to wind. I've heard that the Hakko temperature controlled soldering irons are decent. I'd recommend 80W, with a silicon cord (it won't melt when you put your iron down on itself... which will happen).
     
  4. wayneh

    Expert

    Sep 9, 2010
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    I bought one of these not long ago - along with some extra tips - and have been very pleased with it. Good bang for the buck. Also be sure to get yourself a good supply of good solder.

    http://www.parts-express.com/pe/showdetl.cfm?Partnumber=374-100

    I also have a fast heating gun-style soldering gun that's handy for when you need a lot more heat, like pulling a component out of a circuit board or soldering large wires. For normal stuff, the smaller iron is much better.
     
  5. #12

    Expert

    Nov 30, 2010
    16,284
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    I use a Weller 35 watt pencil iron for circuit boards and "air" wiring little test circuits, then a Weller dual speed 250 watt for, like he said, big wires and sometimes getting a ground wire off of sheet metal.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    Getting back to your pump, you might look at a pet water fountain system. Wall wart transformer plus long life water pump. Or an aquarium bubbler.

    Transformers for 24v are a bit rare for most consumer electronics these days but I believe it's still standard for home HVAC applications, ie. thermostats. Maybe doorbell buzzers too. Any hardware store might have them at a better price than a specialized electronics shop.
     
  7. salty joe

    Thread Starter New Member

    Dec 14, 2010
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    [QUOTE I'd recommend 80W, with a silicon cord (it won't melt when you put your iron down on itself... which will happen).[/QUOTE]

    Yeah, it would not take long either, for me anyway. Thanks for that tip.

    Thanks everyone for all replies.

    I searched a few times for tranformer & found nothing but pricy stuff. Today I searched adapter & think I found what I was looking for.

    The pump I'm looking at has an adapter input 220v, output 24v 1500ma. The sticker on the pump has DC 24v, 1.3a, 30w max.

    The adapter I'm looking at has AC input 100-250v, 1.0A, 47-63hz, output DC 24v, 1.3a, 30w max.

    I want to use this pump with 110v, should this adapter do the trick?
     
  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    It will work, but you are running right up at the edge of what the transformer can handle. The power supply may overheat if it is run continually.

    On the other hand, if the 30W rating of the pump is the peak draw, such as at startup, and only draws 20W after that, it should be fine.

    Something like a Kill-A-Watt meter will let you know what the draw is cheaply and easily.

    If you will be getting a manufactured wall wart, I'd suggest getting a switch mode. They are much smaller and lighter than the linear type that use a 50/60Hz transformer. Switch Mode supplies (SMPS) regulate the current at a very high frequency, resulting in a small transformer for isolation.

    It is very easy to tell the difference between a linear and a SMPS wall wart, if it weighs over 5 oz for 1 amp output, it is linear, the switch mode weigh around 1-2 oz with very high current output, and are very efficient, which means a lower power bill and not much waste heat. The EPA passed a ruling a while back that all "wall warts" need to be switch mode by 2012 or something like that, as an idle/no load linear wall wart still draws 1-2W, whereas a SMPS draws almost nothing.
     
  9. salty joe

    Thread Starter New Member

    Dec 14, 2010
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    Thanks for the heads up. I can use an adapter with a higher amperage as long as it is DC 24v and it is less likely to overheat, is that right? Would DC 24v 5a likely fry this pump?

    The literature for the pump says it draws 25w max.
    The pumps will be run in one of two ways-either with supplied controller-10 seconds at 6.5w, 10 seconds at 12.5w, 10 seconds at 25w for variable flow 24/7 or rapid on/off cycles in the range of 1-2 seconds at 25w 24/7.
     
  10. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    A 5A 24V power supply wouldn't "force" 5A into the device connected to it, but is capable of 5A if the device has a low enough resistance to need 5A.

    A light bulb designed for 500mA @12V will use 500mA when connected to a 12V 500mA supply, or a 12V 200A supply. The Current rating is a "max capability". The voltage of a wall wart needs to be exact, the current needs to be "equal or greater than" device needs.
     
  11. salty joe

    Thread Starter New Member

    Dec 14, 2010
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    Thanks for that straightforward explanation.
     
  12. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Harbor Freight (depending on your location) has very inexpensive water pumps that run directly off 110V or include a wall transformer. I have a couple that I use for cooling grinding wheels.

    John
     
  13. salty joe

    Thread Starter New Member

    Dec 14, 2010
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    Thanks, but I need a specialized pump & the two brands that run on 110 are crazy expensive. I found a reasonably priced one, (with good reviews even!) but it is 220. Although the current to the pump is only 24v (25w max), I am not real comfortable with 220 any where near a reef tank.

    I guess I could run a 220 line but I think an adapter for 110 is safer.
     
  14. salty joe

    Thread Starter New Member

    Dec 14, 2010
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    The pumps I like are DC 24v and draw 25 watts. Could I splice four of these pumps to a single adapter with output of DC 24v 5a?

    "The EPA passed a ruling a while back that all "wall warts" need to be switch mode by 2012 or something like that, as an idle/no load linear wall wart still draws 1-2W, whereas a SMPS draws almost nothing."

    Is a SMPS more efficient under load? Are they as dependable as linear? I ask because these pumps need to run nonstop. If they are not running, they wont be plugged in.

    Now that I think about it, I don't want to put four pumps on one adapter because I'll lose redundancy. Still curious if it's doable though.
     
  15. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Good switch mode supplies tend to last as long or longer compared to a line transformer/linear regulator supply of the same capacity. The reason is there is very little heat dissipated by the SMPS.

    Heat kills electronics. Example of this is Compact Florescent bulbs. They use a small/cheap switching supply to run the voltage for bulb ballast/startup and run. When these bulbs mounted in an enclosure, such as upside down in a "can light", the power supply dies long before the actual bulb life, but they are sealed and nothing really to do about repairing them.

    You could put all 4 on one, for redundancy, you could use 2 power supplies, each running two pumps. Then you would be running the supplies at less than 50% of their rated power, keeping everything cool running and happy.
     
  16. salty joe

    Thread Starter New Member

    Dec 14, 2010
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    Thanks for that good information!
     
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