Q: Converting RC to PF (7897 Passenger Train)

[Luke_likes_Lego]

Hi all,

I've finally bought a 7897 Passenger Train, which I want to run alongside my PF setup.

I haven't received it yet, but I'm interested if it's possible to route the power from the included:

"white train chassis 6x30 with IR Receivers integrated battery (6xAA)" (see below pic from LEGO/toysperiod).

through to a PF IR receiver, then to either the included motor or a PF train motor (preferably without a (permanent) physical modification).

From what little I know about IR, the unit may have to be receiving an "ON" IR signal from the remote by 'line of sight', to work....so I guess my question is:

Is there a logical/natural/clear/obvious/sensible way to bypass this?

Thanks,

LLL

Edited May 13, 2013 by Luke_likes_Lego

[peterab]

What you know about IR is wrong. It works pretty much like PF except it has only 3 channels. They both use line of sight IR. They both have seven speed increments. They both keep operating if out of sight.

More than likely you will experience a bit of wheel slip from the IR motor. This will be mostly eliminated by replacing the rubber tires on the motor.

Unless you are going to add a few carriages you probably won't need a second motor. If you do need one you are probably better off just adding a second IR moltor and a 9V extension lead. You're other option is to buy two PF motors and appropriate conversion leads. Mixing motor types is likely to put strain on both motors, and eventually to burn one out.

Edited May 11, 2013 by peterab

[Locomotive Annie]

Not entirely sure what you mean by line of sight, but I've operated my RC loco sitting beside my layout board with the transmitter in my lap. I suppose there must've been enough signal reflection for the sensors to pick up the signal. Even though I have PF gear to hand I haven't felt tempted yet to try any conversion work as I'm quite happy with the standard RC setup.

What you know about IR is wrong. It works pretty much like PF except it has only 3 channels. The both use line of sight IR. They both have seven speed increments. They both keep operating if out of sight.

More than likely you will experience a bit of wheel slip from the IR motor. This will be mostly eliminated by replacing the rubber tires on the motor.

Unless you are going to add a few carriages you probably won't need a second motor. If you do need one you are probably better off just adding a second IR moltor and a 9V extension lead. You're other option is to buy two PF motors and appropriate conversion leads. Mixing motor types is likely to put strain on both motors, and eventually to burn one out.

Yes definite agreement from me about the traction tyres, I changed the standard ones for 'O' rings and what a difference it made.

[peterab]

Not entirely sure what you mean by line of sight, but I've operated my RC loco sitting beside my layout board with the transmitter in my lap. I suppose there must've been enough signal reflection for the sensors to pick up the signal.

There is quite a lot of reflection, particularly off ceilings, in domestic buildings. In large exhibition spaces both PF and IR need to be pointing directly at the receiver and have a limited range of about two or three meters. This is particularly so if you try and hide the receiver in a MOC.

[ritzcrackerman]

Have you gotten your answer? It doesn't look like it to me.

If I am reading it correctly, you want to:

Use the existing battery box on the white chassis (AA batteries)

Not use the included IR motor

Not use the integrated IR receiver

You want to use a PF receiver and PF motor so that you don't have to handle two different controllers?

(I'm a bit of a newb, so apologies if I am stating the obvious - it just doesn't seem like the question was answered and instead focus was given to the line of sight portion of your question)

As an aside - the 7897 has grown on me, I'm glad you found one. :) I really didn't like the bugger at first, and the giant nose pieces don't sit flush on the baseplate, but they nailed the look of the ICE. The train looks much cooler if you add in some extra matching passenger cars and extend it out a bit. I would also suggest you mod the leading engine and make it windowless to give it a better look.

[peterab]

From what little I know about IR, the unit may have to be receiving an "ON" IR signal from the remote by 'line of sight', to work....so I guess my question is:

Is there a logical/natural/clear/obvious/sensible way to bypass this?

Have you gotten your answer? It doesn't look like it to me.

If I am reading it correctly, you want to:

Use the existing battery box on the white chassis (AA batteries)

Not use the included IR motor

Not use the integrated IR receiver

You want to use a PF receiver and PF motor so that you don't have to handle two different controllers?

(I'm a bit of a newb, so apologies if I am stating the obvious - it just doesn't seem like the question was answered and instead focus was given to the line of sight portion of your question)

The reason he want to avoid the IR receiver and motor appears to be because of his misunderstanding of the line of sight issue. Without that there is no logical/natural/clear/obvious/sensible reason to want to bypass the IR receiver, which is his question.

[JopieK]

PF line of sight is not so direct as one would think b.t.w., even reflection from walls etc. will let the IR signal reach the receiver is my observation.

"From what little I know about IR, the unit may have to be receiving an "ON" IR signal from the remote by 'line of sight'" at least using the PF there are two modes... the small PF remote sends momentary signals (that are not persistent), the train PF remote sends a kind of signal that is persistent. The receiver is the one that decides whether the signal is interpreted as persistent however!

[zephyr1934]

If you are likely to have a lot of PF/RC trains running, using the RC channels will actually help you avoid conflicts since they are different the PF (4 channels from PF and 3 from RC). The controls are similar for RC and PF, but you will need a separate RC controller (that came with the train).

[ritzcrackerman]

The reason he want to avoid the IR receiver and motor appears to be because of his misunderstanding of the line of sight issue. Without that there is no logical/natural/clear/obvious/sensible reason to want to bypass the IR receiver, which is his question.

Well, let's agree to let the OP confirm one way or another. There are some valid reasons to sticking to one remote, and having more flexibility where the IR receiver is placed in an exclusively PF setup.

[F0NIX]

Ok, no one has explained this the technical way, so here I go:

An IR control system has an IR-transmitter and a IR-Receiver. The IR-transmitter has a infrared light emitter diode (IR-LED). The light has an wavelength just out of the range for what an human eye can see. If you try to point the IR-transmitter towards an digital camera, like on a smart phone, you can see the light pulses on the screen when you activate the sender (does work on iPhone 4 but the light is very dim, show up much brighter on other phones or cameras). The pulses has a frequency. The pulses make a string of 1 and 0, like in a binary code. The 1 can be light on and 0 is the light off (or the other way around). Each IR control system operates in different frequencies and set of codes. That is why the TV-remote does not affect the PF-trains. The code has to be exact for the receiver to accept it as a command to do something.

And because the IR-transmitter is a light source, the receiver have to "see" that light from the transmitter to understand the code. Thus it would work if the light bounces back from a wall or an object. The light is pretty weak so it has only a short range. The range can be extended with some tweaking of the IR LED driver. I have not tried that on a LEGO controller, but have manage to do it on a TV-remote.

Both the old 7897/7898 trains and the newer PF-trains uses IR controllers. But it seems that they operates on different codes or frequencies and are not compatible. I don't have the right equipment right now to record the codes to see what the differences are, but I may do that in the future (if not someone else already has done it?).

And back to the first question: can the power from the 7897 box be used to power an PF receiver. The answer is sadly: NO.

I have both types of train and I have opened mine (completely) and I can't see any way to transfer the power without any physical modifications. Well, you can just squeeze in some leads between the battery poles at the top of the original battery box and attach them to the PF receiver power plug. But then you have to modify a PF wire.

I have just tried to connect the PF receiver to the motor connector on the old 7897/7898 receiver box with a PF-9V extender cable, and then turn on the old receiver and put it on full speed. But it does not work. I tried "driving" the old controller at full speed both ways. I can see there is power out of the old receiver since the light is turning on and off on the 9V light. The PF receiver does not work with an old 9V battery box either (trough an PF-9v cable). So it seems the PF Receiver has to get power on other pairs of wires than the PF-9V extender cables gives out on the 9V side.

So some modifications to the cable or other components has to be done to get this working.

The motor on the old 7897/7898 trains can be used together with PF systems. You just need to have the PF-9V extender cable between the motor and PF-receiver to get it to work.

Hope this was understandable, with my poor English gibberish :)

[Luke_likes_Lego]

Breaker, breaker...this here's the OP

Hi again all - and thanks for taking an interest and offering assistance .

My question was in no way intended to be a discussion about IR, or the physics inherent in its use. Sorry to confuse .

Couple of clarifications will help.

1. I guess I have misinterpreted something I read about 'pre-PF' infra-red remote trains (ie 7897 and 7898 only) years ago
   ie. I incorrectly thought that you actually had to be holding the remote button down to make it go (ie like an accelerator/gas pedal, as opposed to a 'throttle' style. ("They both keep operating if out of sight." Thanks peterab))
   
2. Aim is to use one (PF) remote (happy to include IR motor in the setup)
   

So, from learning (1), here are two alternatives as I interpret things:

Chassis 6x30 + 8886 Extension Wire + 8884 PF IR Receiver + 8886 Extension Wire + Electric, Train Motor 9V RC Train

or

Chassis 6x30 + 8886 Extension Wire + 8884 PF IR Receiver + 88002 PF Motor

Would be interested to hear if anyone sees any problem with either of above....or if I'm missing a better way to do it (for a 'single remote' solution).

Thanks,

LLL

[1974]

The output from the chassis is controlled by the remote, it's NOT a pure 9V box! the Chassis is a batterybox AND a IR reciever built into ONE unit

You need to use BOTH remotes to make that scheme work. Very convolutted, me thinks

If you want to PF that train, buy a new white trainbase and put a PF battery box inside. Peice of cake

I've got several trains with the old IR system and I quite like it. That system does NOT use the same freqs as the new PF IR so that means I got 3 + 2 x 4 channels to run at once (I got several multifunction PF IR cranes etc) ..

[Luke_likes_Lego]

Ahhh, thanks 1974,

I think I understand why I misinterpreted the IR/RC system now......ie. to get power out of that white box, you need to point the RC remote control at it (at least once)

So, that brings it nicely back to the first question:

"Is there a logical/natural/clear/obvious/sensible way to bypass this? [preferably, but not necessarily, without a mod] ?"

Cheers,

LLL

Edited May 12, 2013 by Luke_likes_Lego

[JopieK]

Not without a mod, you could use arduino to convert the RC stuff to PF, it requires some skills though so you might ask some technical person help you out with that. The protocol is the problem. Even when the hardware of the RC and PF systems would be exactly the same, the protocol (the 0's and 1's that form the bit train that has some meaning for the system (eg stop, increase speed, etc)) still remains an issue, so you need a microcontroller (built in in the PF receiver, but one can use like an arduino replacement)

[1974]

It's fairly easy to bypass the IR electronics and use the chassis as a pure batterybox. You'd need a soldering iron though

But why would you? Just buy a standard white trainbase and a PF batterybox and you're in business

[ritzcrackerman]

It's fairly easy to bypass the IR electronics and use the chassis as a pure batterybox. You'd need a soldering iron though

But why would you? Just buy a standard white trainbase and a PF batterybox and you're in business

And not only that, but the IR remote makes a cool train horn noise. Much cooler than the PF remote...

The output from the chassis is controlled by the remote, it's NOT a pure 9V box! the Chassis is a batterybox AND a IR reciever built into ONE unit

You need to use BOTH remotes to make that scheme work. Very convolutted, me thinks

If you want to PF that train, buy a new white trainbase and put a PF battery box inside. Peice of cake

I've got several trains with the old IR system and I quite like it. That system does NOT use the same freqs as the new PF IR so that means I got 3 + 2 x 4 channels to run at once (I got several multifunction PF IR cranes etc) ..

The IR system is not bad. Like previous commenters have said, you can run more trains as you won't have a signal occupied on your PF remote for the IR trains. Plus, the IR remote makes a cool train horn noise, so that's a plus. :)

[Luke_likes_Lego]

Thanks again all,

But why would you?

You might if it's logical/natural/clear/obvious/sensible

But....now that I am wiser .....swapping out the base, or bringing the non-PF remote into the mix seems the way to go.

...and as a bonus I just might get a horn

Cheers,

LLL