# Topic: Found: Inexpensive and Capable Radio Control Unit



## dbodnar (Jan 2, 2008)

Good day! I recently began looking into inexpensive (less than $20) radio control units that can be used with our large scale trains. (thanks to RoyKirk for the motivation to explore!)

I have found a transmitter / receiver pair that can be had for as little as $6.00 (delivered!). This unit is designed for use with LEDs but, with the addition of a single diode, can be used with our trains.

The unit can turn the locomotive on and off and can adjust speed from stopped to full speed in gradual steps with a 3 button key chain remote. Input voltage can be from 12 to 24 volts.

The only deficiency is the lack of a reverse function as you don't reverse LEDs! 

I mulled this over for a time and have designed a simple circuit composed of a relay and microcontroller that adds reverse to the system without modifying the receiver.

I am very pleased with the results I have been able to achieve and wish to share this information with the large scale community. 

My notes and observations are on my web page here:

Article on Remote Control


Please let me know if you have any questions.

dave


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## GaryR (Feb 6, 2010)

Thank you so much. ordering several. 

GaryR


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## Stan Cedarleaf (Jan 2, 2008)

Shades of the old, long gone, defunct RRRemote......







Although I know where 2 of them are still running..









Looks like a fun one, Dave... There's always something out there for us to "play" with..... 

I just gotta try it... 

Thanks so much for the great review....


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## Greg Elmassian (Jan 3, 2008)

how much do the "reversing parts" cost? 

Greg


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## RIrail (May 5, 2008)

Hi Dave thanks for the tip. Any idea what frequency it operates @?

Thanks Steve


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## dbodnar (Jan 2, 2008)

Posted By Greg Elmassian on 19 Jun 2013 08:18 PM 
how much do the "reversing parts" cost? 

Greg 
Greg - the parts for the reverser shown in the article come to less than $10.00 - I can supply a programmed PIC processor for $3 or $4 - the relay is just a 5 volt DPDT. A 2N2222 is all that is needed to drive the relay. Unfortunately I only have a few of the circuit boards on hand so I am thinking about making up another version of the unit with either a piece of perf-board or another circuit board - If there is sufficient interest I can design and manufacture a custom board but it only becomes economically practical when you get 100 or more made.

I also plan on experimenting with adding a relay and the PIC right to the receiver board. That will require some soldering but is not a big deal. If time permits I'll give that a shot soon. I would also like to move to a less expensive PIC as I only need 8 pins, not the 14 pin device I used in the prototype.


There is no reason that you couldn't use a PICAXE in place of the PIC that I used - the programming is trivial and it would allow folks to do their own programming without the overhead of working with a PIC chip.

dave


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## dbodnar (Jan 2, 2008)

Posted By RIrail on 19 Jun 2013 08:24 PM 
Hi Dave thanks for the tip. Any idea what frequency it operates @?

Thanks Steve


Steve - the two units that I have operate at 433 MHz - it is possible that others may use a different frequency.

This is a license free part of the spectrum: Wikipedia Article

dave


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## thumper (Jan 31, 2009)

How about a real 6 channel 2.4 GHZ transmitter and receiver for $26.88! Spend a minute or so on the link below and you will be offered an extra discount. Extra receivers are $9.10. I don't know whether a 10% discount is available here too.

You get everything and know your models won't suffer from interference from others while running.

On recommendation from a friend in the UK, I bought a TX/RX package and then 6 separate receivers for less than $80. They control a sailboat, live steam tug, a couple locomotives [including one live steamer]! One thing to note is that although there is no battery terminal on the receivers, you can connect batteries to any empty channel for power. If you want to control lights, the retracts channel makes that easy.

You get everything, throttle, forward/reverse, whistles, lights, etc. for one low price.

Here's the link to the radio package: 

http://hobbyking.com/hobbyking/stor...de_2_.html

Good luck,

Will.


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## Cmorais (Mar 11, 2013)

Hi all 


I'm sure I'm making a mistake somewhere, but since I'm a civil engineer my electrical knowledge is quite limited, so I ask for your forgiveness in advance







. 
I imagine that the receiver outputs the negative pole of the battery on one of its outputs and varies the other output between +0 V and the maximum voltage of the battery.
If we assume a 24V battery, the motor will see between +0 and +24V on its positive pole, and will spin with varying speed, always in the same direction.

Now, if instead of 0V we supply the negative pole of the motor with a constant +12V, like in the picture, LED remote[/b] , as we vary the output on the positive pole of the receiver between 0 and 24V, the motor will see a negative difference over its poles until we reach 12V, and will rotate in one direction.
At 12 V, it will see no voltage difference across its terminals, and it will stop. 
At more than twelve volts it will see a positive difference and will rotate in the other direction.


I'm sure this cannot work, but why? 


José Morais
Headmaster of the CFLF


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## Semper Vaporo (Jan 2, 2008)

Just follow the flow of current out of the top (button end) of the upper battery in the drawing... it flows down to the top (button end) of the lower battery, and right back out and to the bottom of the upper battery... Oops! Dead short on the upper battery.


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## grsman (Apr 24, 2012)

Posted By Cmorais on 20 Jun 2013 06:51 AM 


Hi all 


I'm sure I'm making a mistake somewhere, but since I'm a civil engineer my electrical knowledge is quite limited, so I ask for your forgiveness in advance







. 
I imagine that the receiver outputs the negative pole of the battery on one of its outputs and varies the other output between +0 V and the maximum voltage of the battery.
If we assume a 24V battery, the motor will see between +0 and +24V on its positive pole, and will spin with varying speed, always in the same direction.

Now, if instead of 0V we supply the negative pole of the motor with a constant +12V, like in the picture, LED remote[/b] , as we vary the output on the positive pole of the receiver between 0 and 24V, the motor will see a negative difference over its poles until we reach 12V, and will rotate in one direction.
At 12 V, it will see no voltage difference across its terminals, and it will stop. 
At more than twelve volts it will see a positive difference and will rotate in the other direction.


I'm sure this cannot work, but why? 


José Morais
Headmaster of the CFLF 

If you are referring to the schematic in Dave's article:
The +12v and ground connections to the relay contacts should be connected to the + and - output terminals of the receiver. These terminals will vary between 0v and +v of the battery (12v to 24v) you have connected to the input of the receiver.
The +12v and ground connections of the voltage regulator should also be connected to + and - output terminals of the receiver of the receiver.
With the relay in the nc position, the output to the motor will vary from 0 to bat+. When the relay is in the no position, the output to the motor will vary from 0 to bat+, but is reversed.
Tom


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## SteveC (Jan 2, 2008)

Tom

You missed the hyperlink (i.e. LED remote) in José's reply, third paragraph.


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## grsman (Apr 24, 2012)

Posted By SteveC on 20 Jun 2013 12:07 PM 
Tom

You missed the hyperlink (i.e. LED remote) in José's reply, third paragraph.










SteveCYou are correct. I did miss that. I don't know where that drawing came from, but it makes no sense at all.
Tom


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## Batsco (Mar 30, 2011)

Posted By thumper on 20 Jun 2013 06:12 AM 
How about a real 6 channel 2.4 GHZ transmitter and receiver for $26.88! Spend a minute or so on the link below and you will be offered an extra discount. Extra receivers are $9.10. I don't know whether a 10% discount is available here too.

You get everything and know your models won't suffer from interference from others while running.

On recommendation from a friend in the UK, I bought a TX/RX package and then 6 separate receivers for less than $80. They control a sailboat, live steam tug, a couple locomotives [including one live steamer]! One thing to note is that although there is no battery terminal on the receivers, you can connect batteries to any empty channel for power. If you want to control lights, the retracts channel makes that easy.

You get everything, throttle, forward/reverse, whistles, lights, etc. for one low price.

Here's the link to the radio package: 

http://hobbyking.com/hobbyking/stor...de_2_.html

Good luck,

Will.


I use HobbyKing products to control all my locos I use their brushed motor Electronic Speed Control (ESC) (which supplies the 5V for the receiver) for the throttle and a miniature DPDT switch glued to and operated by a servo for direction control.

For pictures and advice on how to use this inexpensive way have a look at "Sandstone & Termite" website it's a cost effective way to get into R/C operations.


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## Greg Elmassian (Jan 3, 2008)

The drawing referenced uses the yellow wires to put a dead short on the upper battery. After the upper battery either overheats and/or explodes, the circuitry left still makes no sense. If the controller has a connection through the right side upper and lower connections, that should short out or drain the other battery. In any case, it somewhat reminds me of a perpetual motion machine... 

Greg


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## dbodnar (Jan 2, 2008)

Good day - I continue to experiment with the small RC units. I ran my Shay with six cars the other day and the unit worked flawlessly. 

I redesigned the reversing unit and the software that controls it to make it more reliable and simpler. 

I also constructed the reverser right on the back of the RC receiver circuit board using only 7 components. 

My notes are here: 

[URL=http://trainelectronics.com/Articles/RadioControl-LED-8Amp/#Dead_Bug_Reverse_Circuit_Installation]New Reverser Notes [/url]

The link takes you to the new reverser portion of the web page. 

dave


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## artgibson (Jan 2, 2008)

Posted By Batsco on 22 Jun 2013 04:24 PM 
Posted By thumper on 20 Jun 2013 06:12 AM 
How about a real 6 channel 2.4 GHZ transmitter and receiver for $26.88! Spend a minute or so on the link below and you will be offered an extra discount. Extra receivers are $9.10. I don't know whether a 10% discount is available here too.

You get everything and know your models won't suffer from interference from others while running.

On recommendation from a friend in the UK, I bought a TX/RX package and then 6 separate receivers for less than $80. They control a sailboat, live steam tug, a couple locomotives [including one live steamer]! One thing to note is that although there is no battery terminal on the receivers, you can connect batteries to any empty channel for power. If you want to control lights, the retracts channel makes that easy.

You get everything, throttle, forward/reverse, whistles, lights, etc. for one low price.

Here's the link to the radio package: 

http://hobbyking.com/hobbyking/stor...de_2_.html

Good luck,

Will.


I use HobbyKing products to control all my locos I use their brushed motor Electronic Speed Control (ESC) (which supplies the 5V for the receiver) for the throttle and a miniature DPDT switch glued to and operated by a servo for direction control.

For pictures and advice on how to use this inexpensive way have a look at "Sandstone & Termite" website it's a cost effective way to get into R/C operations.

You did not mentioned the shipping costs that rangefrom 25.00 to 50.00 .Increasec cost a bunch.


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## Martan (Feb 4, 2012)

I live on the East Coast US. I got my hobby king radio for $41 with shipping. Not bad for 6 channel tx/rx.


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## Budd (Mar 22, 2008)

Hello Dave, I expect a pair of the LED controllers to arrive at any time, so I suppose I can find out myself, but do you know if you can solder across an extra set of matching frequency tags? in a transmitter so one transmitter will control to seperate recievers? I hope you get my description. Basically, I have 2 eggliners for the grand kids, the plan is that they will have one TX/RX each, but could I rig a 3rd TX to control both RX's so I can run 2 together, knowing that TX 1 and TX 2 would have to be turned off. 

Wayne


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## dbodnar (Jan 2, 2008)

Posted By Budd on 07 Aug 2013 09:11 PM 
Hello Dave, I expect a pair of the LED controllers to arrive at any time, so I suppose I can find out myself, but do you know if you can solder across an extra set of matching frequency tags? in a transmitter so one transmitter will control to seperate recievers? I hope you get my description. Basically, I have 2 eggliners for the grand kids, the plan is that they will have one TX/RX each, but could I rig a 3rd TX to control both RX's so I can run 2 together, knowing that TX 1 and TX 2 would have to be turned off. 

Wayne 
Wayne - depending on the units you receive it should be doable - note that some of the transmitter / receiver pairs I have received are significantly different - if yours have code ID tags on them it should work - if not they may be on the same frequency.


If you change the transmitter solder pads (seen below) you should be able to change which transmitter controls which receiver.

dave


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## Budd (Mar 22, 2008)

Well my 2 arrived, I was excited as the exterior was identical to yours with different codes printed on each box, but the board was totally different to any that you had photographed  go figure, who can work out chinese production.
I haven't had a chance to have a real close look at the boards yet, that will happen this weekend, I have an engine that will be set up as test mule to see how well this controller works, then into the Eggliners they go, the kids will love them.
I'm into H0 as well and am building a double deck layout, I am going to use LED strip lighting over the bottom level and was worried that it might too bright, one of these should fix that problem nicely.

Wayne


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## dbodnar (Jan 2, 2008)

Posted By Budd on 08 Aug 2013 02:43 PM 
Well my 2 arrived, I was excited as the exterior was identical to yours with different codes printed on each box, but the board was totally different to any that you had photographed  go figure, who can work out chinese production.
I haven't had a chance to have a real close look at the boards yet, that will happen this weekend, I have an engine that will be set up as test mule to see how well this controller works, then into the Eggliners they go, the kids will love them.
I'm into H0 as well and am building a double deck layout, I am going to use LED strip lighting over the bottom level and was worried that it might too bright, one of these should fix that problem nicely.

Wayne

Wayne - have a look inside of the transmitter - that is where you will need to change the coding.


dave


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## Budd (Mar 22, 2008)

Ok Dave, I hadn't opened up the TX yet, only the RX. The size of the RX box intially surprised me but having opened it up I see the RX board is a lot smaller so that will make fitting it in a lot easier.

Wayne


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## Batsco (Mar 30, 2011)

Dave,

Have you made any improvements to this controller?

This looks like an inexpensive way to get remote control.

have you experienced any 'Glitching' with using 433MHz as opposed to 2.4GHz?


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## JackM (Jul 29, 2008)

I just picked up on this thread for the first time but I had an uneasy feeling about using the 433 portion of the UHF band. I've been inactive in amateur radio a number of years so I'm not sure I remember correctly where 433 stands with the FCC. 

In the Wiki page Dave refers to up near the beginning of this thread (June 2013), I noticed this line: 

"In ITU region 2 (the Americas), the frequencies that LPD433 uses are within a band allocated to amateur radio. In the United States LPD433 radios can only be used under FCC amateur regulations by properly licenced amateur radio operators. The conflicting allocations have been something of a nuisance to US amateur operators due to use of the equipment by European tourists in the U.S.[citation needed]" 

I realize these devices are low power, but I wonder if there could be a conflict with acceptable use in the U.S. in some circumstances. 

?? 

JackM


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## dbodnar (Jan 2, 2008)

Posted By JackM on 01 Oct 2013 06:07 AM 
I just picked up on this thread for the first time but I had an uneasy feeling about using the 433 portion of the UHF band. I've been inactive in amateur radio a number of years so I'm not sure I remember correctly where 433 stands with the FCC. 

In the Wiki page Dave refers to up near the beginning of this thread (June 2013), I noticed this line: 

"In ITU region 2 (the Americas), the frequencies that LPD433 uses are within a band allocated to amateur radio. In the United States LPD433 radios can only be used under FCC amateur regulations by properly licenced amateur radio operators. The conflicting allocations have been something of a nuisance to US amateur operators due to use of the equipment by European tourists in the U.S.[citation needed]" 

I realize these devices are low power, but I wonder if there could be a conflict with acceptable use in the U.S. in some circumstances. 

?? 

JackM 


Jack - your concern is valid as there is no FCC certification on the transmitter so it is likely in a foggy area for use in the US - the power is so low that it is not likely to be an issue with anyone (hams included) -- if in doubt don't use it!

I am a licensed ham (N3ENM) so either way my use should be A-OK!

dave


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## JackM (Jul 29, 2008)

Agreed, Dave. Just wanted to raise the point so no one got in trouble for going "experimental".

73,
JackM


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