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Author Topic: Speed reducer - or EPA  (Read 1079 times)

barriew

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Speed reducer - or EPA
« on: December 22, 2016, 02:01:58 PM »

I have almost finished building one of Model Slipway's Rescue Boats which is going to my 6 year old Grandson for Christmas. It is currently powered by a 385 motor on 6 volts. I have a feeling that this may be too much for my Grandson, especially as we need to moderate the speed of fast boats to avoid upsetting the Angling organisation who control the lake. His transmitter does not have EPA so rather than buy a Servo Morph from Action, I decided to build my own Arduino version.
The first photo shows the development on the breadboard. The second two show the final version on an Arduino Nano and small piece of stripboard. As this is only required to limit maximum speed, the Sketch is quite simple. I have ordered an ATTiny 85 controller which should have enough capacity for this and is even smaller.


Barrie
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mudway

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Re: Speed reducer - or EPA
« Reply #1 on: December 23, 2016, 05:24:14 AM »

Would an alternative be to use an Electronize esc where you can actually reduce the maximum speed on the esc itself and turn the wick back up when you want to?
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barriew

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Re: Speed reducer - or EPA
« Reply #2 on: December 23, 2016, 07:59:37 AM »

Probably - but not as much fun %)  In fact I already had the ESC which is considerably smaller than Electronize models. The other option is to use a Tx with EPA, but again the one my Grandson users doesn't have this feature.


Barrie
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Netleyned

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Re: Speed reducer - or EPA
« Reply #3 on: December 23, 2016, 08:05:46 AM »

I would have thought a 385 on 6V
would be well within the scope of a
6 year old.
I built an MFA Pirahna for my 6 year old
Grandson with a 540/7.2V and he copes
with ease.
A restrictor on the throttle stick is another
easy way.


Ned
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Brian60

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Re: Speed reducer - or EPA
« Reply #4 on: December 23, 2016, 07:02:15 PM »

As you are using a piece of strip board Barrie, why not just get a bare arduino chip and socket? solder socket also to strip board. Program chip and then attach it to the socket, that would make for an even smaller setup. An ATmega 8 chipset should be sufficient for such a small application.

malcolmfrary

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Re: Speed reducer - or EPA
« Reply #5 on: December 24, 2016, 09:37:29 AM »

Simplest limiter, a 2 ohm 7 watt resistor in series with the motor for junior, a switch to short out the resistor for grandad until junior figures it out.
And stick some bits of thick rubber band to the pointy end for everybody.  That also helps if the boat is being used to push another back in.
Later, replacing the 385 with a 380 and fitting a smaller prop will help it go properly.
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