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Old Jun 05, 2011, 03:59 AM
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Idea
Drive a Brushed motor without ESC

Greetings,
I have couple of toy planes which has brushed motors. I also has a Dx7. Here is an idea I am working on..

using the AUX channel to On/Off the brushed motor using a servo connected to a toggle switch and a battery. This will be not proportional. Thats ok for me. I can change the altitude using the elevator.

Any advice for me?
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Old Jun 05, 2011, 07:03 AM
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Staffs, UK
Joined Nov 2003
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Well it will work, though a microswitch would make more sense than a toggle switch.

But isn't it easier and probably lighter just to use a small ESC ? There must be thousands of old brushed ESCs lying around that no-one uses any more.

Steve
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Old Jun 05, 2011, 07:32 AM
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Good idea.

I don't have a single brushed ESC with me. Thats why I thought of this idea
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Old Jun 05, 2011, 12:56 PM
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Joined Jul 2005
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Precedent used to make a glider that had a micro switch operated by a servo. I think the servo had a circular servo arm with a notch cut out , the switch would sit in the notch when it was off but when adjusted the switch would jump out of the notch and pushed on by the servo arm. I think thats how it worked anyway, it was a good flyer years ago.

Another option is to buy or make a simple electronic on/off switch plugged into a spare channel.

just checked it was the precedent electra-fly
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Old Jun 05, 2011, 01:40 PM
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Mem Martins, PORTUGAL
Joined Jan 2002
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Hi
Quote:
Originally Posted by mrexcel View Post
Greetings,
I have couple of toy planes which has brushed motors. I also has a Dx7. Here is an idea I am working on..

using the AUX channel to On/Off the brushed motor using a servo connected to a toggle switch and a battery. This will be not proportional. Thats ok for me. I can change the altitude using the elevator.

Any advice for me?
Why not use the electronics of the servo to drive a FET to control the motor?
Is lighter and probably cheaper:
http://www.rc-airplane-advisor.com/e...ontroller.html
http://trebor69.tripod.com/speedcnt.html

Chispas
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Old Jun 05, 2011, 07:57 PM
It's a spiderweb of knit lines
Souderton Pa. USA
Joined Mar 2002
2,638 Posts
If it's a small motor you can drive it right from the servo electronics, no fet needed. Won't be on-off like a switch, it will have a couple speeds. Lighter than a servo and switch because you don't need the case or gears. We used to do it all the time, before micro esc's were available.
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Old Jun 05, 2011, 08:31 PM
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Joined Sep 2006
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As mcross said Its easy enough to use the PC board from any servo, most can drive up to 500 mA, you can replace the 5K pot with a smaller trimmer or even use two resistors and get a bi-directional esc. Used a lot in micro boats or cars. That will drive a pager or M-20/N-20 no problem, boards from a bigger servo can drive a 280/300 size motor too. Today's micro servos have a very small and light pc board
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Old Jun 05, 2011, 09:44 PM
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wow wow wow. This is great. I just want to drive a 7mm coreless motor and I have a broken 3.7g servo.
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Old Jun 06, 2011, 04:11 AM
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Dear Peers,
I got an extra servo..
http://www.hobbyking.com/hobbyking/s...idProduct=7562

Just $3.79.

I got this setup to run my GPS-7 HK brushed gearbox. It works like a charm. I am hoping to build a model with AUW of 25-30g using a 2.5g servo to control the rudder.

Weight breakdown..

1. Airframe = 8g
2. Motor/Gear = 5g
3. Orange Rx = 4g
4. 100mah Lipo = 5g
5. Servo board and wires = 2g
6. landing gear = 2g
7. Rudder Servo = 3g

Total = 29g

This motor and gearbox has helped me to fly even 35g model. So I think I may be able to add a 200mah battery depending on the final actual AUW.

Once again, thank you a lot
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