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Old Nov 26, 2010, 07:42 PM
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Discussion

Question about this motor I found


I have an old battery powered pump for an air mattress which I want to use as a second fan to inflate the skirt of a hovercraft.

The problem is that it takes 4 d batteries which are very heavy. Is there any way to make it so that it will take a smaller battery to power the motor?

I also had a pump which is powered by an AC adapter pluged into the wall, is there any way to make this motor work other then having it plugged into the wall?
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Old Nov 26, 2010, 08:00 PM
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4 d cell batteries is 1.5 volts x 4 = 6 volts. That looks like some sort of brushed motor so you could probably run it on a 2 cell lipo.

You can buy new brushed motor speed controls that have the correct low voltage cut-off for lipo batteries.
http://www.hobbyking.com/hobbyking/s...468&aff=102873
Old Nov 26, 2010, 08:27 PM
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I have a few brushed ESCs and a few 2s lipos, i will give it a try.
Old Nov 26, 2010, 08:37 PM
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What if I do not want to regulate the speed, i simply want it to power at full all the time, is an ESC needed or can i just hook the lipo straight to the motor with an on/off switch?
Old Nov 26, 2010, 10:21 PM
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I wouldn't if you are using lipo's as you risk over discharging it. You can still use an ESC but just assign it to a switch on your radio so you can control starting and stopping it. You can probably even use endpoint adjustment to regulate what power level it comes on to.
Old Nov 26, 2010, 10:28 PM
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Awesome suggestion, I will program it to a switch on my DX7.
Old Nov 27, 2010, 05:16 PM
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Ok so it worked on a 2s lipo with a 15a brushed ESC I have.

I plugged that into the Gear slot on my spektrum (clone) receiver and in my TX my servo travel trows are set to -100 and +100 for gear. Any ideas what I am doing wrong?

Also: I plugged the brushless ESC and motor for the hovercraft into the normal locations and then plugged the brushed ESC into the gear slot with the new brushed motor. When I hook up the 2s lipo the the brushless ESC no lights come on, this probably has to do with my question above though and the switch not working.
Last edited by airbagit13; Nov 27, 2010 at 05:24 PM.
Old Nov 27, 2010, 09:20 PM
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Whats not working? If the brushed esc is working when connected to the throttle channel but quits when connected to the gear channel it is probably due to the esc not seeing the proper signal range needed to arm.

The hovercraft will have to be powered up with the gear signal being at idle so that the ESC can arm and then switched on to power up the motor. Perhaps you need to check how the gear signal is setup (it should be the same as the throttle channel). You might also run into problems with the two BEC's since you have two ESC's supplying voltage (disconnect the red wire of one of the ESC's).
Old Nov 27, 2010, 09:42 PM
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Oh, sorry I was unclear. It works wine then I have it hooked into the throttle channel acting as my normal motor. If I have it hooked into the gear port and plug it in without the brushless ESC plugged in then the light on the ESC goes off and on when I push the gear switch up and down. The fan doesn't do anything but the light turns off and on. When I have the brushless ESC plugged into the throttle port then nothing happens to the brushed ESC when I flip the gear switch.

Which red wire do I cut?
Old Nov 27, 2010, 11:09 PM
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To be more clear the red wire would be the positive lead on the servo connection of one of the esc's (probably best to do this to the lift fan esc).

I suspect that the ESC is not arming correctly on the gear channel because the end points are adjusted beyond what the ESC expects to see.

Perhaps a good way to adjust the gear to use the same endpoints would be to plug a servo (not an esc) into the throttle port and move it from idle to wide open noting the servo arm position at each end. Then plug the same servo into the gear port and adjust the endpoints so that when the switch is moved the servo moves in the same way as it did on the throttle port.
Old Nov 28, 2010, 06:06 AM
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Hi
I suggest to use a "Servo tester" instead of the RC radio receiver to control the ESC
Louis
Old Nov 28, 2010, 11:37 AM
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I am going to try what Helno suggested but what is a servo tester?
Old Nov 28, 2010, 12:23 PM
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I plugged two servos into the channels and they are moving the correct way, my gear switch and my throttle were in sync the endpoints lines up perfectly.
Old Nov 28, 2010, 12:34 PM
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Quote:
Originally Posted by airbagit13 View Post
I am going to try what Helno suggested but what is a servo tester?
Hi
A servo tester is a ppm signal generator
Louis
Old Nov 28, 2010, 01:06 PM
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Think I am going to try to still do it without spending $15 on a servo testor or building my own.

I cut the red wire as you suggested and we have some progress. Now when I have the brushed ESC plugged into the gear slot and I hit the gear switch the speed control turns on and arms but the motor does not run, when I hit the switch the other way the ESC turns off.


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