Questions

David Catton
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Joined: Fri Mar 13, 2009 7:23 pm

Questions

Postby David Catton » Fri Dec 13, 2019 11:15 am

Hi,

I've been wondering about a couple of things so decided to start a topic where ignoramuses, such as me, can ask for advice:

If the Deltang Tx22 can control 12 locos, how do you control a 13th loco? Do the 13th and subsequent locos require another transmitter? And the 25th and beyond yet another?

Is double-heading possible - if so, how can this be done with Deltang kit?

Apologies if the answers are obvious or there is another forum where these questions are already answered.

David C

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JackBlack
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Re: Questions

Postby JackBlack » Fri Dec 13, 2019 11:57 am

Hi David,

I've not tried this, but I think Ted can confirm, you can bind multiple receivers to the same slot on the TX, but I don't know what happens if more than one are switched on at the same time.

So you could have a set of 12 locos bound to the 12 slots on a TX, and then another set of 12 locos bound to the same 12 slots, and then another set of 12 and so forth.

You can also set one loco running, then switch to another and control that one while the first one will continue to run. Presumably you could do that with all 12 slots but you'd need to be pretty dexterous when switching between them all...

I guess there's a point where it becomes practical to have two transmitters and obviously if you have more than one person operating trains, they'll need one each. The one limitation is that an RX can only be bound to one TX. However it's pretty simple to rebind an RX.

Double-heading is possible, I've seen Ted doing it with two diesels. I can't remember if they were both on the same TX or on separate ones.

Cheers, Nick

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zebedeesknees
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Re: Questions

Postby zebedeesknees » Fri Dec 13, 2019 5:52 pm

Quick answers.
A Tx22 can control as many receivers as have been bound to it, each responding to being selected when they are active/powered. Any number of Rxs can be bound to a specific selection, but only those that are powered will respond. So Nick is correct in that you could have as many sets of 12 as you wish.

If two receivers are bound at the same time, they will both respond to the Tx at the same time and in the same way. One caveat, the locos need to be wired in the same way as each other, or if nose to nose like two Cl.20s, the opposite way.

------------------------------------------------
Longer ones.
My two 20s were on the same Tx selection, I used another trick to demo independence, because both locos rely on track power only. One feature of the Deltang system is that if an Rx is powered up and the Tx that is selected to it is driving another loco, then the newly powered Rx will not respond until the speed control knob on the Tx is set to zero. So I could set one loco of a consist moving towards a siding where the second one was parked, and then power the second loco, in this case by setting the point with conditional link wiring. The second loco waits until the first stops to couple. After that, they both move together.

The Tx22 has a 12 position switch referred to as 'selecta' for choosing which loco to control, each position dependent on a receiver in a loco having been initiated to that position by a process called binding. Once an Rx has been bound to a selection on a Tx, it and the Tx remember that, even when either or both are switched off.
If the Rx is later bound - in that same process - to a different switch position, both the Tx and the Rx will 'forget' the previous binding, that linkage having been over-written by the new bind process.

The Process.
If an Rx is powered, and the Tx is not, an LED on the Rx will flash once every few seconds. The Tx needs to be off for approximately 22 seconds, after which the LED on the Rx will commence to flash rapidly. At that point, the 'bind' button on the Tx is held down, and the Tx switched on. Provided communication is established between the two, the LED on the Rx and that in the on/off button of the Tx will flash together in sync for a couple of seconds, then both will stay on. The Rx is then bound to the Tx at that position of the selecta switch.

If the Rx and Tx remain powered and the selecta switch position is changed to drive a different loco, the LED on the Rx will double flash at the same frequency as the earlier single flashes. This indicates that the Rx recognises the signal from a Tx to which it has been bound, but the selecta is not in the same position as it was at the time. The Rx will not respond to the Tx in this situation. If that loco is in motion, it will continue. When the correct position is selected, the Rx LED will come on steady again.

If the Tx is switched off, the Rx will revert to single flash mode but will not go into rapid flash later if it has previously detected the presence of a Tx signal.

This is general, true of the receivers Rx61,62, and 63. I have no experience of the other types.

If you think that this is complicated, the c.v. lists are a lot worse! They differ from each other, and there are different firmware versions over time. This is an indication of what these (Rx61d) receivers can do, if it doesn't put you off! http://www.deltang.co.uk/rx61d-v611-p.htm

Ted.

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zebedeesknees
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Re: Questions

Postby zebedeesknees » Sat Dec 14, 2019 4:42 pm

Double heading.
The simplest way is as described earlier, to have both receivers bound to the same selection on the Tx, but that means that both locos do the same thing at the same time, if they are both powered. If already coupled together, no problem, they will drive as one unit.

Or, with one loco powered, it will move independently and can couple to the train. If the Rx in that loco is then switched off, the second loco can be powered up and that will be able to move independently to couple to the first. The receiver in the first loco now needs to be switched on, and they will drive as one unit.

Switching receivers on and off in this situation requires convenience; here the Rx62 can be helpful, in that it comes with a reed switch and two connections on the pcb which require a short pulse to turn the Rx on, and a longer one to turn it off. It can also be turned off by a long press on the bind button on the Tx, but there is no radio way to turn it on. The reed requires only the proximity of a magnet to switch it, or it can be replaced by a push button.

Alternatively, the two can be bound to different selecta slots, thus being independently controlled; it is handy if these slots are next to each other. The first loco is selected, and backed onto the train, and the second likewise. Here it is important that 'forward' is the same direction on both. Now one can be selected and slowly accelerated until the couplings tighten and then without moving the speed control, the second loco is selected and it will be powered according to the position of the speed knob. Each loco will continue at the last instructed speed when deselected, and respond only when reselected. This double header can continue while a third loco can be selected and driven but if the speed control knob has passed through the zero position then a loco that has been left running is likely to stop when reselected. I don't have a roundy-round to check this last point.

This is a bit trickier than driving with two Txs, but most satisfying when successful.

I use Txs with the 'centre off' option; it might be safer operating the above with the 'low off' option, which gives finer control and a direction switch, a matter of personal preference.

There are other sources of info on line, putting Deltang into a search engine produces a number, including several in RMweb. Some of them relate to earlier versions of both transmitters and receivers, so may not be totally relevant or current.

Ted.

David Catton
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Joined: Fri Mar 13, 2009 7:23 pm

Re: Questions

Postby David Catton » Mon Dec 16, 2019 8:57 am

More questions – and answers. This was ignorant me asking two better informed and experienced practitioners for advice but we decided to show off my ignorance and provide answers to questions that others might have, attempting to attract more to give RC a try:

Q (Me): I assume the booster (if fitted) is inserted between the battery and the receiver and not between the receiver and the motor?

A (zebedeesknees): The motor output from the receiver is bi-directional. You could find a new way to fry both with the booster between the Rx and the motor!

A (JackBlack): The booster goes between your battery/charging/switch arrangement and the Rx. You need to put the switch in the + between the battery and the booster otherwise the booster will gradually drain the battery.

Also if your booster is adjustable make sure you test the output before connecting the Rx. I mentioned on one post, it's very easy to fry these receivers, and I've done it to two of them. It's the most frustrating thing because it's stops your project dead, plus, it's instantly flushing £32 down the toilet!

You also have to be very careful to connect everything correctly and the right way round. Including the boosters. I have in the past broken one by connecting it incorrectly, and then spent ages trying to work out why nothing was working, and it turned out the booster was outputting power, but just not boosted.

Q (Me): At my age, having to maintain wiring under baseboards is a not a prospect I relish. So will it be possible to operate pointwork and signals cheaply using RC products? I see receivers for servos on the Micron website but at £25+ a pop that seems a tad rich. Any thoughts?

A (zebedeesknees): With points and signals, there are two distinct issues - power and control. We need to decide what kind of power we are going to use to move things and how it is to be controlled. And how those two are to be integrated.

Starting with my later idea, electricity. However it is controlled, electricity needs to get to the mover. Battery? Where? Wires? Is there an advantage for battery power here? I am not convinced in any direction.

Whatever, - control. An Rx for each device won't be cheap, and the idea I was working at seems to have been scuppered by the apparent demise of the Plantraco company in Canada. I searched for their website recently, and it has gone, some forums asking if they are bust.

Shame, because some of their radio bits could be useful and economic. They used to sell an Rx with one high power unidirectional output for propeller which is of little use to us, but three bi-directional flight control outputs which could drive coreless motors comfortably. Each one could drive a signal or point motor, bi-directionally, but not with a high current need. They were something like $9 Canadian each. They do only work with an 868MHz Tx though.

JackBlack and I both bought some small linear screw motors that were on eBay, but no longer. These were, I believe, for steering mechs in toy cars, but three could be driven from one Plantraco Rx. They seem to have been replaced by a lot of the same sort of thing, but stepper motor driven.

Could go servo:- https://www.amazon.co.uk/Longruner-Heli ... NrPXRydWU=

There are a couple of Arduinos kicking around here that I haven't looked at for years. JackBlack might be good with C++, I'd have to learn it all over again...

I also found these while looking:- https://www.ebay.co.uk/itm/263849538095

They may have a use, the gears especially, I've ordered ten!

But we still don't have a radio link, and if we are going to use electricity for power, we need wires anyway, so what advantage would there be over simply wiring a motor directly?

My other idea was to use air. This is so old that I actually showed the sketches of it to Alan Gibson at his workshop! He studied them, nodded, handed them back and asked for dimensions..

The core was a 3mm i.d. cylinder that compressed a spring and returned. The mech I lifted from an HO Märklin AC powered loco that had a toggling reverser solenoid. The solenoid core had a roller at the end that ran on the inside of a crank that had a bulge in the centre round the pivot pin, that acted as a cam, so that when the spring returned the core outwards, the roller always landed on the other side of the cam to the one it came from, thus reversing the crank position.

My experiments using a compressor showed that 1 bar was plenty to compress the spring in a 3mm tube, and hardly any pressure was lost even if it was supplied through 100ft of 1mm bore flexible tubing. They also showed that only one tube was needed to go to each point motor, and there needed to be pressure in the pipe only for a few seconds during changeover, so little or no waste of compressed air.

For control, if compressed air was available, modified disposable cigarette lighters, the valves are perfect. With no compressor, a medical syringe would do the trick.

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JackBlack
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Re: Questions

Postby JackBlack » Mon Dec 16, 2019 6:17 pm

David Catton wrote:JackBlack might be good with C++


C#, please 8-)

This looks interesting: https://www.raspberrypi.org/forums/viewtopic.php?t=79090. I've been looking for any excuse to buy a Raspberry Pi...

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zebedeesknees
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Re: Questions

Postby zebedeesknees » Thu Mar 19, 2020 6:16 pm

Further to Nick's reply in another thread recently on this subject, some answers to questions anticipated, that haven't been asked yet.

On batteries there were some references on supplier websites that I found confusing, like 'C' and 'S'.

'S' stands for cell - (yes, obvious!). Each cell provides a nominal 3.7v DC, so a 3S battery is 3 cells providing a nominal 11.1v DC.
'Nominal' because each cell can be charged to a maximum of 4.2v - and usually is by most chargers - and discharged to around 3v before any protection circuit cuts in. If there isn't one and the battery continues to be used, it will fail, never to be charged again.

'C' stands for capacity - which is why it doesn't stand for cell. But it isn't quite as simple as that. For our purposes we just need to keep safe, so we don't need more than a battery rated at 1C. That means that a battery of 700mAh rated at 1C can safely provide 700mA continuously for 'up to' an hour.

A 3000mAh battery rated at 20C, the sort used by vapes and high powered electric race cars or drones can provide 3A x 20 - 60A for 3 minutes. This is not what we want or need, but the 3Ah is desirable. The protection strip in the link that Nick provided limits the output of such a battery to 3A, or 1C.

So we can use batteries with high capacity and high C rating safely if we control them with such a protection strip, even if they have an internal protection circuit that allows a much higher C output.

Another implication of the C rating is when charging. The second link that Nick offered recently showed a charger and batteries. The charger is rated at 600mA, the same as the nominal capacity of the batteries, but they are 5C, so though they can supply a full 3A for up to 12 minutes (5 x 0.6 = 3, 60/5 = 12) the charger will only charge each one at 1C, so could take up to an hour to fully recharge each one.

There are high C rated chargers available, and provided they are not rated higher than the battery will work fine and possibly reduce the charging time, but at the expense of a higher current running through the connections which could produce heating in undesirable places...

The ones I currently (sorry) prefer are these:-
https://www.ebay.co.uk/itm/TP4056-MINI- ... 3448430077

They plug into a male USB 'B' connector and show by LED when charging and charged. They work with bare cells and batteries with internal protection. The output can be fitted with cables to any connector suitable for your needs. I am intermittently working on a connector system that will use small magnets to make contact under the loco, having discovered the connectors to the protection strips mentioned above are 0.004" thick nickel coated ferrous.

This is assuming the use of a single cell. Multiple cells in series, as in 3S batteries, require more complicated charging circuits as they will not recharge properly in simple series. Better is to use a single cell and a booster such as Pololu. https://www.ebay.co.uk/itm/POLOLU-2096- ... 3249146567

For increased capacity at 1S, cells can be connected in parallel provided that they are in a very similar (± 0.1v) state of charge when connected.

Ted.


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