Building a radio controlled (electric) traction engine

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tom_tom_go
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Re: Building a radio controlled (electric) traction engine

Post by tom_tom_go » Thu Apr 26, 2018 7:40 am

A traction engine popping wheelies, very cool.

I like it Greg, the speed changes have improved it's running.

Can you not fit a speaker in the roof of the cab?

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Re: Building a radio controlled (electric) traction engine

Post by gregh » Thu Apr 26, 2018 7:45 am

FWLR wrote:
Thu Apr 26, 2018 7:36 am
Loved the video Greg, it was a bit steep that hill…. :)
Think the wheels need a pivot of some kind to keep them both on the ground on uneven surfaces don’t you think. In the full scale ones they have them don’t they.. :thumbright:
It was working fine before I added the chains.
I've loosened off the pivot screw and will see tomorrow if that helps or whether I need to loosen the chains as well. I did try today with both chains loose and I was surprised that it ran straight BUT everytime it hit a small bump, the steering wobbled around and then came back straight - a very unprototypical look, so I tightened them again.
Maybe if I loosen just one side.

As to the hill - the wheel was slipping on the axle which may have contributed to the 'fail to proceed'.
Greg from downunder.
The Sandstone & Termite's website: http://www.members.optusnet.com.au/satr/satr.htm

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Re: Building a radio controlled (electric) traction engine

Post by gregh » Thu Apr 26, 2018 7:58 am

tom_tom_go wrote:
Thu Apr 26, 2018 7:40 am
Can you not fit a speaker in the roof of the cab?
I have recorded that sound on the video onto a 20 sec sound recorder card. I only have a 25mm mylar speaker to test it, and it was just hopeless. I could fit two, 40mm mylar into the roof but I have used them before in a little diesel and the volume is so low that you have to be up close and personal to hear it.
I don't have the 'depth' under the roof to hide a 'real' speaker, although I suppose I could hide it in a box that stuck down.

And if I do put them in the roof, I have to get the wires up there somehow. The roof support tubes are hollow but I want the roof the pull off, so if I run any wires that will be difficult.

I need something to remind me that it is turned on too, but the sound card would only play while running so that won't help. I need a light.
Greg from downunder.
The Sandstone & Termite's website: http://www.members.optusnet.com.au/satr/satr.htm

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Re: Building a radio controlled (electric) traction engine

Post by FWLR » Thu Apr 26, 2018 8:00 am

And loosening the chains would help I’am sure Greg. They hang down on the full scale one’s on one side slightly so has to compensate for any rough roads. If you see one been driven, you will see the driver constantly adjusting the steering wheel to keep the engine running straight… :thumbright:
412In_Burrell_Traction_Engine_Green_7.jpg
Rod

Life is so easy when I run my trains. :thumbright:


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Re: Building a radio controlled (electric) traction engine

Post by philipy » Thu Apr 26, 2018 8:25 am

I think the reason why one side is slack on the real thing is that the steering chain is continuous and wraps several times round a horizontal rod/pulley, which rotates one way or the other to change direction, so its always tight on the side into which it is turning. Having both sides slack will always tend to create a self centring effect, assuming they are both the same length, since the weight trying to drop down on both sides will be the same.

Having said all that, the actual run is very impressive, but won't leave much brain power spare to run trains as well!

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Re: Building a radio controlled (electric) traction engine

Post by Lonsdaler » Thu Apr 26, 2018 9:52 am

You could try and pick up a laptop speaker - generally compact, but of better quality than the mylar 'tranny' types.
https://www.ebay.co.uk/i/231573236571?c ... 342&crdt=0
Phil

I am not young enough to know everything anymore...

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Re: Building a radio controlled (electric) traction engine

Post by gregh » Thu Apr 26, 2018 11:00 am

Lonsdaler wrote:
Thu Apr 26, 2018 9:52 am
You could try and pick up a laptop speaker - generally compact, but of better quality than the mylar 'tranny' types.
https://www.ebay.co.uk/i/231573236571?c ... 342&crdt=0
Thanks for that idea. I had never thought about laptop speakers being small.
I've ordered some similar ones already.
Greg from downunder.
The Sandstone & Termite's website: http://www.members.optusnet.com.au/satr/satr.htm

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Re: Building a radio controlled (electric) traction engine

Post by Lonsdaler » Fri Apr 27, 2018 9:59 am

gregh wrote:
Thu Apr 26, 2018 11:00 am
Lonsdaler wrote:
Thu Apr 26, 2018 9:52 am
You could try and pick up a laptop speaker - generally compact, but of better quality than the mylar 'tranny' types.
https://www.ebay.co.uk/i/231573236571?c ... 342&crdt=0
Thanks for that idea. I had never thought about laptop speakers being small.
I've ordered some similar ones already.
Not really my idea, but you're welcome. I think it is 'Chuffed to Bits' who supplies his sound cards with a laptop speaker as standard. :)
Phil

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Re: Building a radio controlled (electric) traction engine

Post by tom_tom_go » Fri Apr 27, 2018 11:06 am

I use Peter Spoerer for laptop speakers. You need to be careful with buying small speakers on eBay due to quality and if it comes with a well made back box for reverb:

http://www.peterspoerermodelengineers.c ... fo.php?p=4

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Re: Building a radio controlled (electric) traction engine

Post by gregh » Sat Apr 28, 2018 1:14 am

tom_tom_go wrote:
Fri Apr 27, 2018 11:06 am
I use Peter Spoerer for laptop speakers. You need to be careful with buying small speakers on eBay due to quality and if it comes with a well made back box for reverb:

http://www.peterspoerermodelengineers.c ... fo.php?p=4
Well I've ordered some cheapies, so I'll report how they perform when they finally arrive. I'm not concerned if I've wasted a couple of dollars with free postage from China. AS I've said above, I doubt I'll waste any more time on the traction engine getting sound in it anyhow.
Greg from downunder.
The Sandstone & Termite's website: http://www.members.optusnet.com.au/satr/satr.htm

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Re: Building a radio controlled (electric) traction engine

Post by steamer68 » Sat Apr 28, 2018 3:02 pm

Greg a fantastic job on your radio controlled traction engine and I really like the sounds. :thumbright:
Regards
Kevin

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Re: Building a radio controlled (electric) traction engine

Post by gregh » Mon Apr 30, 2018 12:54 am

As soon as I started testing I noticed an intermittent control problem. I'm using a picaxe to control the motor speed, direction and steering. But there is some interference which causes the picaxe to stop and restart its program.
I am sure this is what is happening as if it’s in reverse at the time, when I restart it is in forward. This can only happen in the startup part of the program. The engine restarts when the throttle is returned to stop.
It happens mainly at full throttle (which is only about 55% of battery volts), but can happen at anytime, any direction and on straight or curves.
It doesn’t seem to do it on the bench, even when I put pressure (load) on the wheels.

After much investigation using my oscilloscope, I have managed to overcome the problem (I hope - who knows with intermittents?). But I don't understand why.
It seemed to have something to do with 400mV dips on the 5V caused by the steering servo which seems to take spikes of 1 amp when it's moving. I won't go into all the things I tried, I ended up feeding the 5V to the picaxe and Rx via a diode and then a 47,000uF capacitor. I only had a 'normal' diode so that's a 0.7V drop to the picaxe, but I'll get a Schottky type later.

Just for info, this is the voltage trace before I 'fixed' it. The fuzzy line is a 100mV peak-peak exponential type wave caused by the RX (why? who knows?). The dips are 400mV due to servo current. With the diode and supercap, these are both halved.
cro4 servo interference.png
And this is the circuit:
TE circuit.jpg
Greg from downunder.
The Sandstone & Termite's website: http://www.members.optusnet.com.au/satr/satr.htm

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Re: Building a radio controlled (electric) traction engine

Post by FWLR » Mon Apr 30, 2018 7:00 am

All well beyond me Greg, but I’am glad you have it sorted. :thumbright:
Rod

Life is so easy when I run my trains. :thumbright:


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Re: Building a radio controlled (electric) traction engine

Post by ge_rik » Mon Apr 30, 2018 7:06 am

I admire your tenacity, Greg. I must admit that I'd have assumed there was a dodgy connection if it was happening in the field but not on the bench, but the oscilloscope trace suggests something else is going on. Presumably, as the difference between this program and your usual one is the addition of the steering routine and circuitry, then it makes sense that this is where the glitch is happening. But as to why ....... ?

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Re: Building a radio controlled (electric) traction engine

Post by tom_tom_go » Mon Apr 30, 2018 9:35 am

Surely there is a faulty component causing this?

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