Radio Control

[Frank]

Hi Brian,

I am guessing now as I cannot see your installation.

I think the way you had the battery connected before would have meant that the LED on the switch would have come on when you switch on the power irrespective of anything else, so having corrected that it will not just come on as it did before.

I think that the LED on the switch and the one on the board should do the same thing, so if the one on the board is flashing and the one on the switch is not, there must be a problem with the wiring to the LED on the switch.   This could be an open circuit or a short between the LED pins.   Another possibility, not likely if I understand correctly what you have done to fix the power supply connection, is that the LED is now wired the wrong way round.   This can only have happened if you have reversed the LED connection when fixing the power connection, which I do not think you have.

I have tried one of my TXs and found that it operates as follows:   With the receiver also switched on, the LEDs both light and stay on continuously.   I am assuming however that you do not yet have the receiver connected up.   With the receiver switched off, the LEDs again come on continuously.   The only time the LEDs flash about 13 times (it seemed like 13 but I would not swear to it) is if you go into the binding process.

Binding is linking a new loco to the transmitter.  To bind the loco you switch the loco on and watch the LED on the receiver board flash and at a certain point you switch the transmitter on whilst holding down the red "bind" button.   The transmitter searches for the new loco and binds to it.   Whilst it is searching the LEDs flash and when it has found the loco the LED changes to continuous.   If it has not found the loco after 13 or so flashes it gives up and the LED comes on continuously.  That sounds something like what you have described.

Based on the above I think the transmitter is entering the binding mode when switched on, which suggests there is a short to the 0v line on the connection to the bind switch.  If this is the case, none of the other controls will have any effect.

You say that pressing the bind button causes the LED to dim.  This again suggests that there is something wrong with the bind button wiring, it sounds like pressing the button shorts the 3.1v line to 0v but I can't see how this would happen.  I suggest you check the wiring around the bind button.  There must be something wrong there I think.

I think that is about as far as I can go with what you have described so far.   I suggest you check the points above and see if you can find anything.

Frank

[Frank]

Hi Brian,

I have been looking at you circuit diagram which of course is different from mine as it is a different TX.

Can you just check for me that you have R36, R38, R41 and R43 connected correctly please as it occurs to me that a problem with these might also have a similar effect to a short on the bind button wiring.

Thanks

Frank

[gtmspyder]

Thank you Frank, duly noted.

Further investigation will commence soon.

Regards,

BrianT.

[Frank]

Brian,

Can you check R37 and R42 as well please just for completeness.

Thanks

Frank

[gtmspyder]

Hello Frank. Right here we go then.

As you know, my controller has 4 potentiometers, numbered R30..R32..R34..R39 from left to right when viewing the circuit diagram.

I don't know whether there is a right or wrong way to connect them, but they are all connected the same way, when viewed from the rear of the case, with the three solder pins facing down, I have connected 0v to the left hand pin in each case.  I thought that the fixed element of resistance was the same from end to end, with the central connection to the wiper, so that provided they were all connected the same way, they would all give the same results, give or take there tolerances.

The fixed resistances are numbered R31-R33-R35-R36*-R37*-R38*-R39-R40-R41*-R42*-R43*-R44   The numbers with a star behind them are the ones you have asked me to check for wrong connection, as they are fixed resistors, I did not think they had any orientation????

Regards,

BrianT.

[Frank]

Hi Brian,

The way round that you wire the potentiometers determines the sense of the control ie whether you turn them to the left to increase or to the right.   I think that "off" should be with the slider to the 0v end but I'm not sure, I will check my TXs.

The point about the resistors you have starred is not that there is a right way or wrong way round, they are as you say just passive components.   The point is that I think a short to 0v or an open circuit somewhere round there would cause the symptoms you describe by taking the pin 5 to 0v, or the same for pin 7.  (I do not know what effect shorting pin 7 would have but it was worth checking I thought.) I was asking you to check if there was a short anywhere (or possibly a wrong connection by which I mean connecting them to the wrong line).   

For example, a short connecting the switch that is connected across R37 (I can't read its number on the photo of the diagram) directly to the 0v or 3.1v or with an open circuit in the R37 or R38 connection would I think cause the symptoms you describe.

One way you could check this is if you check the voltages at both ends of R37.   I can't read the component values but I'm sure you can work out what they should be, it's just a simple potentiometer, I would guess about 1.0 to 1.5v at the top of R37 and about 0.5v at the bottom.   If the top end is 3.1v or the bottom is 0v there is a problem.   Similarly you could check the voltages at the terminals of the red button.  One should be 0v and the other should be about 0.5 v or 1.5v depending on the setting of the direction switch.   If they are both 0v, or if one is 3.1 v, there is a problem.

Hope this makes sense.

Frank

[Frank]

Brian,

As an alternative, you could check if there is a problem with the controls attached to pin 5 by simply unplugging the three way plug which connects to pin 5 and seeing if the LED on the board still flashes when you turn the power on, or if it comes on normally.

Frank

[gtmspyder]

Hello Frank.

The on/off switch LED is kaput, so that sorts that problem, so I am going to replace the LED element of the switch, with a separate 3mm LED, which I will mount in a more viewable position in the case.

While I'm on with this change, the LED as supplied in the packet, is supplied with dropping resisters to put in series, I can't say what resistance they are, but I am assuming that the resistance is sufficient to allow the LED to be sufficient for mains use, therefore, as I am fitting it to a 3v supply, can I discard the supplied resistor in this application?  And if that is the case, will the 220 ohm resister still be required in the circuit?

I am rewiring the right corner of the circuit box, ( as viewed from my pictures ) this is where the on/off switch wiring and several resistors are clustered together, so to test the switch, I had to disconnect the wires,  and I removed the switch to make things even easier.  I was going to discard the switch altogether, then thought about the LED's I had in stock, and decided I would just replace the LED and take the opportunity to reposition it.  I will also take this opportunity to spread the components a little to open the wiring, if only for fault finding  ::)  Whilst I could find no apparent faults there during disassembly, but it was very difficult to check with the crowding.

One last thing, Frank wrote:-  The way round that you wire the potentiometers determines the sense of the control ie whether you turn them to the left to increase or to the right.   I think that "off" should be with the slider to the 0v end but I'm not sure, I will check my TXs.

From this, I take it that the 0v should go to the end of the resister nearest to the anticlockwise position of the slider to give the usual "Turn clock wise to increase whatever action"? If this is so, then I think my connecting the 0v black where I have done was correct.

Unfortunately Frank, I had started to dismantle the circuit before your last two posts arrived, sorry.  So the voltage tests I cannot do, hopefully, reassembly will deliver the correct operation if my interpretation of the pot connections is correct.

I await the answers to my query regarding my use of a different LED and it's associated resister, and whether I have connected the potentiometers correctly?

Regards,

BrianT.

[Frank]

Hi Brian,

You are spot on with the potentiometers.

LEDs often seem odd.  They are basically diodes.   They light up when conducting so when forward biased.  They do not light when reverse biased but generally have low reverse voltage limits so reverse bias is generally best avoided.   When conducting they need a voltage of a couple of volts or so (depends on the type and colour) to turn on then the voltage will not rise much as the current goes up.   They need a resistor to limit the current to the value needed to generate enough light.  If you omit the resistor the current will be too high for the LED to tolerate.

For an indicator LED like this, the current is usually about 5 mA.    So you need a resistor that will drop a  couple of volts less than the supply voltage when passing about 5 mA.  If you do not include the resistor the LED will likely blow due to the high current.

The LED you are talking about here has a supply of 3.1 v I think and so you need to drop about 3.1 v - 2v = 1v.   A 220 ohm resistor at 5 mA drops 1 v so this will drop the required voltage.  Sounds OK.

LEDs are not used in mains circuits but you may have been supplied with a resistor of about 1k which would do for a typical battery supply voltage of 6-12 v.  If so it will be too high for this application but you do need to include the 220 ohm resistor.


I suggest you press on with the rewiring then test it again.

Frank

[gtmspyder]

Bless you my son, your place in heaven is surely assured. ;D ;D ;D

I will start the reassembly tomorrow morning probably, you did say you were in all day Sunday didn't you. ::)

A very very big thank you for your time and trouble Frank, I'll bet you wished you had talked about something else at Kegworth ;D

Regards,

BrianT.

[Frank]

Hi Brian,

I am just very pleased with the response to Kegworth, there are several people having a go now and I have other similar discussions running elsewhere so you are not alone.

I think radio control has a lot of potential and so I want people to try it as this is the only way to understand why it is different.   I have no commercial interest in this, I am retired now and happy with that, but I do have a bit of an evangelical streak when I come across a good idea.

So I am happy to provide help and encouragement where I can.

Frank

[gtmspyder]

Hello Frank, it's a relief to hear I am not alone requiring help ::) ;D

Here we go with another update:-

1st.  The Lipo 3.7 batteries I purchased are wired to the TSB plug, which is fixed to the batteries, the wrong way round to the TSB socket supplied with the pre-wire leads and extra socket from Hobbytronics,  the red lead iS neg, and the black lead is pos, which is probably why I fried the 1st charger.  I am still awaiting an exchange for this which I have returned to Hobbytronics, although to be fair to them, it was clearly not a faulty unit as I thought.  Coincidently, while I was waiting a descision from Hobbytronics, I purchased a second charger, and some more pre-made leads and the additional plug, so that I could be getting on with things,  

Today, I connected the Lipo battery to the receiver and train to test the newly assembled transmitter, when the receiver LED did not light, I wondered if the new batteries had insufficient charge in them, so I connected my new charger to the battery, and I may have fried the second charger now.  This is when I decided to check the polarity, and discovered that if there is a correct way round to connect the TSB plugs, then either Hobbytronics are not doing it correctly, or the battery manufacturer, which ever, one of them is wrong. >:(

Any way, with the battery leads now reversed from what they were, I have a green receiver LED lit for ten flashes one second on and off  , and then the green LED flashes very quickly on and off.

Now to the transmitter:-

Upon switch on, the PCB board and the new 3mm case mounted LED flash in unison, well that's a first for me. :D  Thirteen quick flashes, a slight stutter and the a slightly slower flash rate forever it seems, and no knob twiddling, switch switching or bind button pressing has any effect.

At first, things seemed to be moving along in the right direction, but I could get no response from the loco.  I had disconnected one sides wheel pickups and soldered one of the receiver leads to the motor terminals, when there was no response again, I removed the other side wheel pickups, and soldered the other receiver lead to the other motor terminal, and that seems to have altered things again, but not for the better.

I really am getting very fed up with this whole exercise.

It struck me tonight, that I can't see how you designate which of the three separate control pots you can choose to bind to,  there are three what appear to be, forward/ reverse toggle switches, yet the pots have a definite centre detent in there travel as though they are for forward and reverse on the pots anyway, so, all in all, I am in a muddle, I don't really know what I am doing, and despite Franks sterling efforts to fill in the whole I am digging, the last bloke I spoke to, doffed his cork dangling trilby and said Gday Pommy ::)

I think I'll just chuck the whole lot into the bin, and stick to what I know.

I'm sorry to all those who have been following my rambling on radio control, in the hope that what I write will somehow help them, but I have to admit, I'm defeated, or I purchase a ready built controller.

Regards from a very frustrated bunny,

BrianT.

[Frank]

Hi Brian,

Very surprising about the battery being wired the wrong way!   At least you have found out now.   Very odd though, as you said you would expect something like that to be consistent, these are intended for people to just plug in to their equipment not have to check first.  Maybe it was intended for a piece of equipment that was itself wired the other way round.

The receiver sounds to be working OK.   The slow flash is the receiver looking for the transmitter it last was connected to.   After a period it changes to scanning for any available transmitter and that is when it changes to rapid flashing.   So far so good.  It is when it changes to the rapid flash that you can initiate the binding process with the transmitter.

With the transmitter, you seem to have sorted out the LEDs which is good.  However it sounds as if it is still entering the "bind" process when you switch it on which suggests a short somewhere around the red "bind" pushbutton.  Normally, when switched on it should just come on steady not flashing.

I suggest you check the voltage either at pin 5 or the equivalent contact on the red pushbutton, whichever is easier.   Without the red button pressed it should have a positive value, with the button pushed it should be zero.  The positive value will depend on S33 the middle direction switch.  One way it should be about 1.5 v, the other way it should be about 0.15v but not quite zero.   Depending on how sensitive your meter is, the best way to check might be to see if the voltage changes from 1.5v to a small value as you change the direction switch.  If it does not move above zero then there is a short to 0v somewhere.

Frank

[gtmspyder]

Hello Frank, smee again. ::)

After another careful look over the circuitry, whilst I drew what I had actually done, rather than the circuit diagram's theoretical circuitry, I have now got to this stage.

Switching on the transmitter gives me 13 flashes of the transmitter PCB LED, and the case mounted LED, then both LED's are off.

Plug in the receiver PCB, and the receiver PCB LED does several quick flashes and then stays lit.

So, all seems as it should be, but no matter how much knob or switch twiddling, there is no response from the motor.

I began to doubt the motor itself, because it is brand new, so I did a straight connection from Lipo battery to motor terminals, and the motor runs.

So I am nor further forward than before.

And I still do not know how to designate which motor pot to which motor, so I just turn them all, I know the inertia pot can mean the motor has a delay when turned in one direction or the other before it starts to turn, but again adjusting the inertia pot from one end to the other has no response from the motor.
So once again, I am stuck.

Regards,

BrianT.

[Hugh Norwood]

Brian - I sent you a PM