More thoughts on Radio control

tramcar trev said:
Is this the correct section for this???
More thoughts on Radio control….
I really do have to take more Stillnox, I wake up in the middle of the night with these ideas. This one lets me use 1 transmitter to control 2 trams ( or if you could find a cheap 3 channel all proportional channel Tx then this would work with that as well)

What if I could get 27 MHz RC transmitters and receivers very very cheap? If say I could get a 2 channel brand new 27 MHz transmitter for $16 and a whole pile of receivers with crystals all round to match for $10 each and ESC’s for $8.61 ea…. And given that unless you’re Ross at best I can control 2 trams at once I could set up the receivers so that one of each channel could give me speed control over one tram? There would be a separate Rx on each tram and the ESC would be either on Ch1 or Ch 2.
With me so far? Also remember that all I am after is really control over speed, reversing is manual as is swinging the trolley pole…

So I could control 2 trams that corresponded to either of the 2 channels on the Tx. Each joystick on the TX would have underneath it written the numbers of the trams that channel could control. It would mean that trams would sit in the sidings and would not respond until the Rx was switched on.

Alternately I could at that price buy 6 Tx enough to control 12 trams at 1 per channel.
Now this all appears too simple for me so there must be some reason why it can’t be done. Remember each Rx would have a mating crystal for the Tx; each Rx would be switched on to activate the tram. And yes I would have to supply 6v for the Rx, easily enough via an L7806 regulator….

There is also an RxESC combo available but it’s not as cheap…
Why am I bothering you may ask, I have the keyfob thing running well…. I know I can control 2 trams at once with the key fobs, one in each hand but it’s the button pushing and response time that’s grinding me a bit, with a spring loaded joystick I have a dead man’s handle built in…. I'd use the Deltang unit but by the time I land it here its expensive and you also have to switch between the train your controlling.

But there must be some reason this can’t work because if it did everyone else would be doing it…..
Some of you will get the jist of what I'm blithering about and some of you will be able to answer the question "is this going to work?"
Click to expand...

Trev,

I am doing exactly what you want to do using cheap 2.4GHz Hobbyking TX/Rx combos.
In fact I can control 3 locos from one transmitter though 2 of them answer the throttle and direction at the same time so I rarely do that.
If I want an exciting session the 2 locos in opposite directions and use 2 passings sidings to avoid collisions.
If you want more info just give me a yell.
 
Tony Walsham said:
The big problem with taking the pots out of the case and putting them in a different box is that you will no longer have any spring loading on the sticks to make them self centering. Which, with your multiple locos being controlled, would be vital for an emergency stop.

BTW, I make an R/C switch with two .1 amp transistor outputs. I also make a DPDT relay that when connected to the switch does what you want. Max load is 1 amp but could be upped to 2 amps easily enough. Unfortunately I cannot make them as cheaply as the Chinese made stuff.
Click to expand...
Yes... I did say a dead man's handle would be desirable and with the pots that would not happen unless I could find auto self centring pots of the correct value..... But realistically (unless you're Ross or maybe a helio pilot) controlling more than 2 at anyone time is going to be frought with frought... I'm off to the bead shop to try and source some wooden beads to use as handles, If I go down the extending of the pots road I'd make up miniature brass tram controller handles with a wooden knob... The advantage of using the pots is that you can set one tram running and it doesn't stop when you let go of the knob.... Hopefully my Automatic signalling system can keep trams under control and if the Rx is kept "hot" by an onboard battery then it should work swimingly ( he says with both fingers X'd) It works now with the Key Fobs and the only reason I'm getting rid of the key fobs is their response time.

So give yourself a plug for the R/C switches. Basically I would like a switch that can handle 12V @ 1/2 amps (otherwise I have to use a switch and then run the output thru a miniature relay - which is not impossible) to control lights and on the steam tram the smoke.... What do yours cost Tony and the size etc. And before any one says I'm a Walsham stooge I swear I have no connection whatever apart from comments on the forum... But its good to buy off someone who has to abide by Australian Consumer laws and speaks English.

So can anyone tell me anything about the current draw of the receiver side of things? If I buy 1800mAh receiver battery packs (which would fit nicely under the tram floor) how long would they power up the receiver?
 
ROSS said:
Most RC switches for on/off lighting etc operate on a max of 6v because they operate from an RC receiver and uses its power. Receivers operate on 4.8v or 6v depending on make. The one shown below is about the size of a servo connector lead.

[font="times new roman, serif"]This unit is (MAX SUPPLY 6V.)[/font]
[font="times new roman, serif"]This is a miniature DUAL RC switch for handling loads up to 2. 5A per switch.[/font]
[*]
[font="times new roman, serif"]The control of these switches are unique in that they only need a single channel to operate both switches. The state of each switch depends on the position of the stick (or the programmed lever position on the transmitter). When the switch is closed, the supply voltage (absolute max is 6.0V) appears across the positive and negative output pins. This is suitable for driving strobes, high-bright LEDs, lights, smoke systems, or 5V relays.[/font]​
[*]
[font="times new roman, serif"]Can be configured as a single RC switch if needed.[/font]​
[font="times new roman, serif"]Load rating 2. 5 amps max per switch (@ 5 V)[/font]​
[font="times new roman, serif"]Supply voltage 2.7v - 6. 0v DC (DO NOT exceed 6. 0v)[/font]​
[font="times new roman, serif"]Weight 4g with RC cable Size 1.0" x 1/4" x 7/16"[/font]​

images

Click to expand...

Ok, sounds good. Now the esc from HK also has a BEC function. For those not up with the jargon the the ESC supplies the power to run the receiver and switch form its supply i.e. the battery or the track power. Seems most ESC's have this capability this means in effect you don't need a separate 6V supply for the Receiver (I think). So where is this one available from and emma chisit?
 
Thanks for your reply Tony. I currently use battery (three trailing cars with TE Rx) but still maintain the possibility to fire up my Bachmann locos which are still track powered. A winter project to convert probably.
My power supply for track power is adjacent to my Ham radio transmitters (HF not VHF or above) and their respective power supplies but I must add that I either play trains OR radio: never both at the same time.
Did you tactfully avoid the "price part" of my post? ;)
 
ROSS said:
Every RX needs a power supply 4.8v or 6v battery and the switch gets its instructions and power via the RX as does any servo plugged into the receiver.
Click to expand...
Yes, of this I am aware what I was trying to say is that the ESC provides power for the RX viz;

Turnigy 20A BRUSHED ESC

Got an old brushed motor laying around and want to put it to good use?
The Turnigy brushed ESC is an excellent speed controller with a linear throttle curve, Lipoly/NiMh ready and programmable braking.

Features:
The break function can be turn on/off by the jumper
Battery type can be chosen by a jumper
For Lipo the threshold for each cell is 3.0v, less than the threshold ESC will gradually reduce the output power
PWM frequency is 2KHz
Over heat protection over 110C
Throttle signal loss for 1sec will gradually reduce the output power, after 2sec completely cut-off

THIS IS FOR BRUSHED MOTORS ONLY, WILL NOT WORK WITH BRUSHLESS MOTORS.

NO REVERSE FUNCTION.

Spec.
Cont Current: 20A
Burst Current: 25A
BEC Mode: 5v/1A
Lipo Cells: 2-3
NiMH : 4-10
Weight: 17g
Size: 45x21x8mm

Note the BEC mode, 5 V / 1 amp; BEC is battery elimination Circuit....
one catch with these ESC;'s though is that not all will take 12V and they are rated in the Number of Li-Po cells they can handle. this one can take 3 cells (around 12v)
 
The Devonian said:
Thanks for your reply Tony. I currently use battery (three trailing cars with TE Rx) but still maintain the possibility to fire up my Bachmann locos which are still track powered. A winter project to convert probably.
My power supply for track power is adjacent to my Ham radio transmitters (HF not VHF or above) and their respective power supplies but I must add that I either play trains OR radio: never both at the same time.
Did you tactfully avoid the "price part" of my post? ;)
Click to expand...
Hello Alan.
Having the R/C in a trail car makes a big difference to how well any 27 MHz systems works.
For a start you get better reception when the antenna is not tangled up in on board wiring. Running the antenna around the inside top edge of a box car say, greatly improves the range. Motors also radiate RFI so having the antenna away from them works wonders.
Secondly, even the length of wire between a box car and the loco will greatly aid controlling the back EMF spikes that can also disrupt AM Radio signal reception.
I used to get fantastic range with my RCS systems mounted trackside and very good range when used in trail cars. However, ultimately the all round superior performance and low cost of 2.4 GHz park flyer R/C equipment spelt out clearly the end of older AM and FM systems would happen sooner rather than later. So I changed over myself.
I am currently testing a prototype new Deltang DSM2 TX20 handpiece for use with my current RCS ESC's. So far so good. More info soon.

No I wasn't avoiding mentioning price. I can well understand dealers not wanting to sell off old stock cheaply.
I am referring to what old 27 MHz AM and 40 Mhz FM bring on the second hand market. They are hard to give away, let alone sell for $$$$$$
 
After due consideration I think I'll get the HK 6 channel setup with 6 Rx and 6 ESC's....
So I now think that knobs are better than joysticks they can be set in place and only need to be touched to control an individual tram when it needs "controlling" other wise it's just rumbling along at a sedate pace and the auto signalling controls the traffic generally.
Ok that means I'll have to take the Tx out of its box and put it in my own box I don't foresee any problems there trimming the joysticks is not a problem because all I need is speed control.... BUT what I want to know has anyone else done this? Especially considering the range of movement in the Joysticks is about 90 degrees.... But forward motion is limited to 45 degrees on the Joystick... I checked the net to see if I can "Bind" the Rx with the joystick fully to one side or the other as I only need control over one direction and if that's going to give me 90 degrees of throttle control. I don't know; a guy who thought he was going to sell me a $600 Tx told me that would work....
I've done quite a bit of reading on the net as per Ross' suggestion, Gregh's pages are handy especially for noobs. Nowhere has this issue been addressed i.e. making all joysticks full throw single direction throttles..... Mode 6????
It may also be a function of the PC programming available with the HK setups. Fortunately these only cost AU$29 so I guess I can afford to experiment....
Thoughts, Ideas from the floor?
Now if I can get this to work it would be brilliant on a large railway as you would not have to switch between locos on the control box as they each have their own knob....
 
Here is my proposed wiring diagram. No need for a separate Rx power supply, the ESC supplies power via its own BEC circuit. In fact you can't run a battery Rx supply while the BEC circuit is working. I have renomenclatured the channels to car numbers. So Car 1 will be on Rx1, Ch1, car 2 on Rx2, Ch2 and so on. Reversing will be by way of the DPDT centre off switch; everything will be live while the pole is on the wire but power to the motor is controlled by the centre off switch. A simple resistor supplies power to the lighting and a 3 amp diode prevents the anti flicker Capacitors discharging back into the overhead wire... So what have I forgotten?
Cost to control 6 tramcars? AU$ 139.87 + postage.

4faa62430ef14b19b00269b9813159f4.jpg
Now all I have to do is pay for this stuff....​
 
With regard to the Tx potentiometers, I haven't done the replacement thingy, but this is how I thought it might work....

Assuming the pot in the transmitter is linear, and that centre stick is half way round, and that you get 360 degrees of movement then the stick movement would require a resistance range from (Tx pot R) X .375 to (Tx pot R) X .625. So if the Tx had say, a 1000 ohm pot we would ideally like a full travel pot between 375 ohm and 625 ohm. In fact we would actually want a 0-250 ohm pot and a 750 ohm resistor on the common leg of the pot.
Zo :nerd: ze final version is much simpler : for full travel of the joystick you need a pot a quarter the value of the Tx pot with the remaining three quarters as a resistor in series with the pot.

Now I freely expect this rambling to be complete bollocks, but I offer it as a starter for 10.
 
Ok, sounds good.... Having done a bit of a check most pots have 270 degrees rotation but for reasons unknown logarithmic ones have 300 degrees.... But I feel you are on the right track. I'll try as follows by practical measurement.
1) measure the resistance of the pot
2) measure the swept resistance from "off" to "full on" ( remember I want all the channels to be full stroke throttles except maybe one which may have a reversing ESC which would need centre off) and use a pot with that value ACAP.
3) Deduct one from the other and add that amount via a fixed resistor on the replacement pots.
It may be even easier as ch5/6 have knobs and I'll have a look how they are wired up and the values and see if that will work on all channels.....
All very interesting....
If it all goes pear shaped I'll revert to your idea~!! And if that doesn't work I'll spit the dummy and sit in the corner and sulk....
 
Hyacinth has told me I can buy this stuff when I get my tax refund.... In about 10 days....
 
Just happened by, thought I would chime in- I'm doing some of this stuff (rewire the tx with rotary pots, etc) and it works well for me. One thing, if you spend a bit more money on a motor controller you don't need the reverse switch. The pololu 18v7 ($30US) will do bi-directional. Knob in the middle stop, full left, reverse, full right, forward. I have a standard 5K linear pot wired to my channel 1 and it does great. Now, that said, I prefer a reverse switch so seeing as how you can configure the pololu via it's USB port, I just changed it to only go one way and I have the second channel throw a relay in my Aristo RS3. I think I like that better but if you were going to do a bunch of locos on one tx, getting rid of the extra chan for the relay is probably good. Anyhow, here is an early version of my tx box. Note this is an old airplane 72mhz radio, I have a hobbyking hk6 but have not chopped it up yet (although I have looked inside) Also, I only have the one loco and I have not put the reverse switch on in this pic. I routed out a place for my tablet since I'm also doing some 802.11 stuff to throw turnouts. The buttons sound horns...

txhack.png
 
Thanks for posting Martin. I think I've been following your blog for a while - inspirational stuff.
 
Martan, Thanks for the input. I'm reasonably confident that extending the wiring to pots on the front panel of a box is going to work. Did you have any trouble getting suitable pots or did you use the originals? The ones I have seen inside Tx don't seem to have a spindle and nut to secure them. I'm bidding on some reversible ESC's on eBay hopefully I can get them for around AU$20. In my case as I run single pole trams I have to swing the pole to reverse so a switch is a good safeguard to prevent backpoling which I have discovered is very dangerous.... The beauty of the HK RC gear is that each Tx costs the same as a reversing ESC so If I don't get it right first go its not much of a loss, the PCB inside is about 100mm x 50mm....
 
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