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Toeffelholm
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Hi,

I have two of Davids small Tx2 2,4Ghz transmitter modules, which enable you to design your own small one hand control. Either for Davids tiny combined Rx/esc boards or for ordinary Spektrum DSM2 receivers as well.



(figure 1:24)

So beside my bigger transmitter that is made from an Dx5e, I wanted to build a second smaller one.






First I needed a case and, as some may know my design preference, I looked for something special. The case in the picture I bought years before on a christmas market, just because I liked it, but I never used it since then. It may be originally thought for snuff tobacco.

I got a 10kOhm pot with center-click from David, that he uses for his Tx21/Tx23 and purchased a nice poti-knob from the electric-guitar parts need. I want to install 3 switches, one for on/off, one for loco selection and maybe one for light. I had a few in the Rc-parts chest.







For connecting the pot to the Tx2 I used a common Servo plug with wires. The red and brown +/- wires are soldered to the outer connections, the orange "signal" wire to the middle pickup of the pot.

The Plug has 3 jacks, that would fit to the 3 pins of the Tx2. But the middle wire of the plug may not be connected to the supply voltage of the Tx that is to be given to the Tx's middle pin row. The voltage of the analog input devices need to be 1,55V. There is a reference voltage ( Vref=3.1V), that can be picked up at solder pads on the Rx. With an additional resistor of 10kOhm, serially connected to the pot, I get a voltage divider that provides the half reference voltage of 1.55V between the outer connections of the pot.







For the supply voltage I use a 9V battery for now. For connection to the Tx serves a 2-pole plug, that can be found as "BEC-connector" and that matches the pin-distance of the Tx2.

As the switch for binding is rarely used and the case is easy to open, I decided to install a micro slide switch inside the case. Binding is activated when the upper pin 5 is connected to 0V at the lower pin row. I used the "bind plug", that comes with the Tx2, for building the bind switch.







I placed these first parts into the case for testing and it works fine. I will change the 9V battery to a single LiFePo or Li-Ion roundcell to make place for the other switches. Also the status LED has still to be build in.







My antenna solution for now is just a piece of isolated wire going through the case. I think I will add a piece of brass coloured plastic tube there.



To be continued

Juergen

Last edited on Mon Apr 1st, 2013 10:51 am by Toeffelholm

DavidT
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Very nice. Sticking out is fine but you could also wrap the aerial round the outside of the case (flat against the brass).
Regards, David.

Giles
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Love it!

Toeffelholm
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Thank you David and Giles.

David, yes that's a good Idea, thank you.

Juergen

Bernd
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Juergen,

For some reason the pictures are not loading into the forum over here. At least I can't see them.

Bernd

bobquincy
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I love it!  I wonder if a miniature knife switch exists, kind of like those used in Young Frankenstein?  That would add a real steampunk look to the switch!

Herb Kephart
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And a small tazer--so that you could have sparks going up a "Jacobs ladder".


Herb

Toeffelholm
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Hi,

Do others also have problems seeing the pictures?

@Bernd, the pictures are stored on a German server, on a " .de " domain.

Any restrictions in your system?

Juergen

Bernd
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I tried just going to the domain and I couldn't see the pictures there either. It's looking like I'm the only one that can't see them. In any of the other sections I have no problems. The other thing I noticed was that "spell checker" isn't working either.

Running Windows 7 Proffesional and Explorer 9. I seem to be OK on other forums though.

Could be something on my computer changed from the last update. I hate when that happens. I'll have to check things out.

Do you have any other pictures else were on this forum I can try?

Funny part is I can go to your web site and see everything. Just having trouble see those pictures you osted here. Interesting.

Bernd



Last edited on Wed Apr 3rd, 2013 01:28 am by Bernd

Toeffelholm
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bobquincy wrote:
I wonder if a miniature knife switch exists, kind of like those used in Young Frankenstein?  That would add a real steampunk look to the switch!


Bob, thank you for mentioning this. I searched for this kind of switch longer before but didn't know the right term.


Juergen

Toeffelholm
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Next steps

The DelTang Rx60 and Rx61 receivers provide the dedicated selection of up to 12 locos with a appropriated multi position switch in your Tx.
For this you convert the switch in a kind of potentiometer, but with fixed resistor values. On Davids website you find schematic examples (pdf) e.g. for a 6 way switch .

I want to use a common 3 pos toggle switch for the selection of three locos. The switching states of this switch are " on - off -on " and so this kind of switch can not be wired like a "normal" multi position switch, where each position has its own connection.

The wiring diagram for this switch you find here (for 100% throws)

And this is the way my prepared switch looks like. I use channel 2 for loco selection, red wire is the positive side and is connected to Vref = 3.1V again
(lustre terminal in the picture).








A third switch I want to use for the headlights. This is an 2 position switch, for front and rear lamp.






The 3pole plugs I used here are from these header sockets, that can be broken in needed length. Together with the pin header you can also make very small pluggable connector






Everything placed into the case looks like this. Voltage supply comes fron a 3.6 V LiIon battery (non rechargeble, 2.6 Ah) with AA size, so that it fits into a standard AA battery tray.
Perhaps this will be replaced with a Lipo of suitable geometry later on. But this was my quickest find and with a current demand of the wired Tx2 of about 40-50mA this battery will last for quite a while.






More wires, more chaos, so quickly closed the lid.





Juergen


Next, my settings for Tx2[img][/img]

Last edited on Sat Apr 13th, 2013 07:06 pm by Toeffelholm

Toeffelholm
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I have corrected my last post. I had a fallacy in using the simple 3pos toggle switch with the resistor arrangement for multi position switches.

The switching states of this switch are " on - off -on " and so this kind of switch can not be wired like a "normal" multi position switch.

I found a solution to use this switch with a modified resistor arrangement. David continued this Idea and drew a new wiring Diagram for this. Link in the post above.


Juergen

DavidT
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Juergen, master of simple 3-position switches! I had not noticed the blue light before, looks really nice.
dt.

Bernd
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Juergen,

For some reason I can see the pictures now. Must have been something with the computer.

Nice job on that transmitter. Reminds me I need to finish mine one of these days.

Bernd

Toeffelholm
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My settings



If you use Tx2 in mode 1, as default, you may only change trimming of the throttle pot. I do not need the inertia feature so I switched my Tx2 to mode 2, without inertia. Also I wanted to have throw options to 100% for all channels.

This setting procedure for this two settings is activated by connecting the solder pads "pin 8" and "Vref=+3.1V". In addition to this bind switch has to be "off" in case of mode choice and "on" in case of throttle options choice. You can read the detailed instructions for the setting procedure here.


As I want to make more than one Tx2 and for playing around with the setting possibilities, I made a little auxiliary tool with a kind of claw from a 2 pole piece of the pin header and a toggle switch. The bind switch you see on the right inner side of the case.








For throttle I use a pot with center click indication in the middle position. When I switched on loco and transmitter the first time, the motor was buzzing in center position of the throttle knob. That's an indication for that the center click position is not exactly enough at the middle resitor value. In this case you just have to do some trimming of the throttle channel (normally channel1).

Turning the throttle knob a slight way to the left or to the right will make the motor to fall silent. That is the direction you have to keep in mind for the trimming, in my case to the right.


For actvating the trim mode of any channel I need to connect "pin7" at Tx2 to 0V. I soldered a simple plug and switch tool for this as well. The throttle pot is plugged to the channel that has to be trimmed.





After pulling pin7 to 0V with the switch the LED on Tx2 goes off and I turn the poti to the right end position. The LED starts flashing, whereby each flash indicates four steps of the 512 you have in each direction. I wait for about 5-10 flashes, don't remember the exact number now, and then loose connection of pin7 to 0V with the switch. Turning the throttle to center again and switching on the loco gave the wished result. Maybe you don't hit the correct trim at the first time, so you have to give some flashes more or have to go some flashes back in the other direction. Detailed instructions for this again here.


You may also need trimming if you use a servo e.g. for uncoupling.



Juergen

Last edited on Sun Apr 21st, 2013 09:42 am by Toeffelholm

DavidT
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Nice. Do I see a slightly non-standard aerial connection?
dt.

Toeffelholm
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Hi David,

I used a single pole pin header and socket for connecting to the piece of wire going through the brass case. Works good so far.

Juergen

Toeffelholm
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Steampunk Transmitter the third.

A DelTang transmitter I have built for my friend KEG.
Brass box is made by a mutual friend of us.

Here I used Davids 12 position switch for loco selection (DelTang Selecta function)





Juergen

Last edited on Mon Sep 16th, 2013 05:28 am by Toeffelholm

Si.
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Wonderfull electronics implementation Juergen !

& great tutorial !

If I need to know (& I might, soon) this is where I'll go.

Thanks for sharing your work.

Love the steam-punk look.

I like your friend KEG's models as well.

All the best

Cheers

Si.

DavidT
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I agree, stunning!
dt.

Helmut
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@toeffelholm
Here is a miniature knife switch you might like. Was the smallest I could find so far.

W C Greene
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Wow, that makes me think of the doctor throwing the switch and saying "IT's ALIVE!". Looks to be a suitable on/off device for the transmitter or punk locomotive. Maybe a whole bank of them to control layout lighting...Hmmmm...

Woodie

fanai
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Yes love the feel of these - thanks for the tutorial, will pass on to a friend who is interested in RC
Ian

Toeffelholm
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Many thanks for your interest guys.

W C Greene wrote:
... Maybe a whole bank of them to control layout lighting...Hmmmm...


At the time I use several chinese LED dimmer to control several lightings of my friends and mine layout boxes.



But I want to build them into a nice precious timber chest, with nicer knobs, amperemeter, voltmeter ...
And such a knife switch will be the perfect main switch.


Juergen


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