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Pickup Winder Question

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I'm making an electric pickup winder using the following parts from radio shack:

20 gauge hook up wire specs

25 ohm rheostat adjustable resistor specs

on/off rocker switchspecs

battery sanp on connectorspecs

1.5-3Volt motorspecs

9v battery

heres a diagram of how i wired it (from left to right: battery and connector, on/off switch, resistor, motor)


Whenever I first turned it on, it worked perfectly. Then I turned it off and started to mount it onto the fram I am working on. Then I turned it on again to show my dad how it worked and it didnt work. I ran some by checking to holding the battery directly againts the motor prongs, the resistor's prongs, and the switch prongs and none of them worked. I then let it alone for a while and about an hour later I checked it again and it worked for about 5 seconds and then slowed down and quit. My conclusion is the battery is run out. The battery was bran new so I either wired it wrong or it was a defective battery. All the connections seem nice and tight. If anyone notices anything wrong with the wiring or supplies I used I used let me know. Otherwise I'll just try a different battery. Just in case I do have a bad connection would a bad connection cause this problem?

Edited by silvertonessuckbutigotone
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To state the obvious...

1. If it worked at all, it MUST be right (it would not have worked otherwise).

2. If it is no working, power is not getting to all relative points.

If you are SURE that nothing has changed from the original setup, I would definately try a new battery (as you have said).

Please let us know how it goes.


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Well, my theory for the bad connection thing is if it has a bad connection and the initial amount of power the battery is putting out isnt enough because the connection is bad, then the battery is straining to send out more and in turn killing the battery very quickly. I tried a different battery and it worked, but again for a short period of time, but this test was useless, considering the battery was used. I will check the connections more thuroughly and get a new battery to check it again and see how it works, I might even post pics of my ghetto spinner.

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Your 25 ohm rheostat is wired directly across your battery 25 ohms across 9v will draw around 300mA current which will suck your battery flat pretty quick. Remove the negative from the rheostat so that the variable resistance is in series with the motor that way all the current is pulled through the motor. You will have to make sure of course that the current and voltage drop across the rheostat are within specs of it's power rating or you could overheat and burn it out.

I don't think your switch is wired correctly either. if it should be in series with your one of your lines (+ or -) the way you have it in your drawing looks like it puts a dead short across your battery in the "on" position this will stop the motor running but suck the battery flat very quickly!


Edited by KeithHowell
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I wouldn't connect the ground to the Rheostat. It will add a second load in parallel to it that draws about 360 mA; quite a lot from a 9v battery. In a series circuit, consider both the motor and the rheostat resistors. The higher resistance of the two will have more voltage going acrossed it, they will both have the same current. The voltages of the two (or more) will always sum up to 9V. As the resistance increases, the current drops. Obviously, with less voltage, comes less speed. If you want the lowest speed turned to the left and the highest speed turned to the right, wire it like this (shown from the back side, not the adjustment side):


As well as that, I recomend wiring in series with that, a resistor 2-5 times the value of the motor resistance (I hope you have a multimeter!) and is able to handle the wattage. This will keep the voltage and current down and keep you from causing a short with you motor and blowing up your battery and\or motor (I'm guessing it's less than 5 ohms). It's also common practice to wire a .1uF (104) cap in parallel with the motor. I highly recommend reading up on Ohm's Law if you haven't done so already. Do a search, there's plenty of sites that give you that info for free.

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