Power Functions 7745 Advice Request

[martyboy70]

Hi there Ive just joined the forum as I have recently rediscovered the joys of Lego and was wondering if I could trouble those of you with a lot more knowledge for a bit of information.

A bit of background first:

Having recently split up with my partner and lost my job I found myself in a new home with no toys and no money to buy them for when my son came to visit.

While talking about this with my mum she mentioned that she reckoned she still had all my old(80s)Lego sitting in a box in the loft(Why couldnt she have kept my Generation 1 Transformers and Star Wars stuff as well?)

Within a minute I had the ladders out and was scurrying up to the loft feeling like a kid at Christmas.

Memories came flooding back as I remembered the many years when I had built,modified,rebuilt and merged the bricks in this box into everything and anything my imagination could come up with.

Grand Prixs at the 6395 Racetrack, taking off for an exotic location from the 6392 Airport and filling up the many cars, vans and lorry sets I had at the 6378 Service Station all felt like yesterday rather than 20 odd years ago.

I spent a couple of nights scouring through the catalogues for the 80s to see which sets I had but didnt have instructions(most still did) and then downloading the instructions to build them all again and have been bitten by the Lego bug one more time.

My favourite set though was always my 7745 HST until I broke one of the wheels off the motor(I can still remember how bad I felt to this day) so that was the first set we built together and while my son loved helping with the build he was not so happy that it went round the track at a snails pace and then derailed after a lap and a half.

I looked into buying a new 12V motor from Ebay but they are very expensive, then I remembered seeing a big Lego trainset in Argos recently and got to wondering how these modern sets were powered and could the old fave be converted to run on this system.

So after a bit of research and some correspondence with a Youtube poster I have decided to convert the 7745 to Power Functions on as tight a budget as possible(I should be able to sell my transformer for nearly what the PF parts will cost) rather than spending more acquiring a 25 year old 12v motor.

This week I have got the IR box and Remote Control but my main questions are regarding battery power and motor choice.

1) I see there are 2 PF battery boxes-one for AA and one for AAA batteries-with the AAA box seemingly being smaller and designed for trains. The thing is I already have loads of rechargeable AAs and the AA box seems to go for about half the price of the AAA one so is it just too big and heavy to use in a train specifically a 7745?

2) The older Technic battery box can be picked up for pennies and supplies the 9V required by PF and looks small enough to fit. Obviously the terminals would be different but I can solder and once in the train it wont be coming out.So could this box be used with a bit of electrical "persuasion"?

3) I see there are 2 motors and one(8866) is not very well regarded.The better option is currently OOS at Lego UK but on the US site it has a date for resupply.

Does anyone know if it will be available from Lego UK again?

Thanks for reading and thanks in advance to anyone who offers some info.

[Sokratesz]

With some minor modifications you should be able to fit a large 6xAA technic batterybox into the engine of 7745. There is enough space inside for the 14-stud long batterybox.

The IR receiver should fit just in front of the driver seat if you remove the grey 'control panels' (assuming the signal will go through the windows)

- Sok.

Edited August 24, 2011 by Sokratesz

[AndyC]

1) The AA battery box is a bit bulkier, so a little harder to hide and being mainly for Technic creations it doesn't feature any studs unlike the AAA one. That said it'll certainly do the job, so you could always pick one up and use that.

2) No soldering required, you just need to put a PF extension cable between the IR reciever and the battery box, since it includes the necessary adapter to connect to older 9V connections.

3) Your best bet is to ring LEGO customer services and ask, they're super helpful with things like this. Alternatively you might be able to pick one up on Bricklink, though I don't know how comparable that is pricewise.

[Sokratesz]

nvm misread

Edited August 24, 2011 by Sokratesz

[roamingstop]

If your train models are not going to be running 24/7 (or even 1 hour continuously) another solution is the 9V PP3 battery box, which is the smallest one of the lot, and is a similar size to the current PF battery boxes. However the PP3 wont last so long in terms to charge.

. These boxes are not too expensive, but you still need the converter cable mentioned above.

There is one guy selling custom PP3 -> PF adapter on Bricklink for around 10 USD. I have a few of these and whilst not pure Lego, they can fit inside a 3x3x6 stud space... typically making the walls 5 studs apart; and I was able to update some older 9V models in a minimal way.

[pikappa79]

if you can help, a few days ago I posted this:

http://www.eurobricks.com/forum/index.php?showtopic=59054

[martyboy70]

First of all a big thank you to all of you who replied-it is much appreciated.

@ Sokratesz

Thats the one I was thinking of(5115 i think)as they are available for £2-3 delivered but as you say that would force the IR unit right up under the clear glass spoiling the look and charm of the drivers cabin with the little computers but I understand that I will have to make compromises.

BTW i was looking at your 12v era station and that is a great piece of work there.

@ AndyC

Would that be an 8886 I would need to get in order to hook it up to the Technic battery box.

I took your advice and phoned Lego-as you mentioned very helpful and what they told me was the parts to make the PF motor are in short supply and the 1st batch have been allocated to the US in late October with Europe being restocked in the New Year which is too late for me as I want to get the 7745 rolling again for my sons birthday in December.

She did suggest getting it sent to a US address but the postage would put the price way up.

My options look like buying one at a premium price from Ebay or getting the other motor which I really dont want to do as it gets terrible reviews and people say to avoid it like the plague so decisions to be made on that one.

@ roamingstudio

Thats another good option space wise and I actually have a couple of rechargeable pp3 batteries sitting about doing nothing but worry about the lack of lifespan-would it be a lot less than 6 AAs?

Hes only at mine 2-3 nights a week but I wouldnt want it slowing to a halt after 15 mins.

@ pikappa79

Thanks for the link its given me a good guide as to what I will need to move or remove once I decide on the final parts line up.

One question-who drives the train:)

Thanks for the answers-I have remembered another question i had.

It regards the lighting-will it light up enough on 9v and will I be able to splice the grey 12v cables onto the PF power feed?

We have the technology to rebuild this train:

[AndyC]

Yep the 8886 cable will allow you to connect PF parts to older 9V equipment. As far as the motor goes, whilst the old one isn't great it should suffice for pulling a small train like 7745. The one issue you might encounter is that you'd need another 8886 cable and on some train designs you can run into issues with the cable getting caught on the train baseplate when connected to an 8866 motor (since it's slightly taller than an old style 9V plug) - maybe someone else with 7745 can advise better on that one.

[roamingstop]

I remember reading somewhere about the PP3 that if should give about 1 hour of continuous play under a single charge with a EN + 4 carriages. I have one at home and could set up an equivalent circuit at the weekend to check for you. It is a cheap option.

[Sokratesz]

AA's are easier and cheaper to get though, and rechargable AA's are cheap too, so I would go with the large technic battery box option.

I'm not sure about the exact dimensions of the IR unit but I'm sure you can work it away in the drivers cabin nicely - I could even try it for you back at home this weekend if you want.

- Sok.

[pikappa79]

@ pikappa79

Thanks for the link its given me a good guide as to what I will need to move or remove once I decide on the final parts line up.

One question-who drives the train:)

the minifig in the other car!

[martyboy70]

Again thanks for the (quick) replies.

If an engine and 4 carriages is an hour and you count the 7745 as an engine and 2 carriages you might reasonably expect to get an hour and a half or thereabouts and this would be ample I think.

As far as batteries go I have enough rechargeables for either option so the main concerns become price and size.

Looking at Ebay there are plenty of both available for around the same price so thats not really a factor.

As far as size goes the PP3 one would certainly be a lot better from a "stealth" point of view as with the AA one the IR box would be shoved right up to the window of the cab and be very noticeable-would it work reversed with the IR box at the rear of the engine and the battery box at the front- so I may go the way of the PP3 but then would have a bit more modification to fit connectors.

I read some reviews about the 8866 motor regarding what you said about fouling and causing derailment issues so I think it is definitely out.

Will my 12v track be OK with a PF motor?-I know its the same gauge.

Thanks for the offers to check for me guys but I cant ask you to spend your precious weekend time doing this.

I have a busy weekend ahead of me sorting out this lot:

[roamingstop]

Here is the original post about the PP3 -> PF adapter.

It seems his store does not list them anymore; but basically the + and - pins are connected directly to the + - of the 9V -> PF cable; the two C1 / C2 lines are floating. Therefore it cannot power a motor directly - but it does power the IR receiver which in turn generates the PWM output for the C1 / C2 lines.

The 9V battery box is a nicer looking solution.

Edited August 25, 2011 by roamingstudio

[martyboy70]

I was swaying towards the pp3 option until I had a look at my batteries.

My rechargeable AAs were quite expensive and have a capacity of 2500 mah and the 9v ones are only 170 mah which is about 7% of the capacity of the AAs plus I would need to adapt the cabling so Im now looking at the 6xAAs either old school Technic big or the newer one if I can find one at a good price.

But you are so right about the pp3 option being far better looking and Id imagine easier to "build in" to a train

Edited August 25, 2011 by martyboy70

[roamingstop]

Or if you go along the adapt cabling path... make your own long thin set. But this weekend I will set up a 4512 + load of carriages; and a new PF motor and see how long it lasts at speed 7 on a flat circle... with a new Duracell PP3. (I dont have rechargable ones).

[martyboy70]

That would be great as it would give me an idea of how long a pp3 would last as I can have both charged and use one and keep the other on standby(might not bother with the lights after all)

[peterab]

If an engine and 4 carriages is an hour and you count the 7745 as an engine and 2 carriages you might reasonably expect to get an hour and a half or thereabouts and this would be ample I think.

You are comparing apples and oranges here. The emerald night carriages have newer 9V wheelsets which have far less friction. I wouldn't count on getting more than an hour with your 12V wheels. If you can fit the 6 AAs in, that's what I'd use.

In regards to the RC motor, while it does get bad reviews, they mostly come from AFOLs who do train shows, they worked OK for most kids. I have a pair of them, and when combined with an RC base they make a very nice loco. The main disadvantages are the slightly higher connector which is not a problem if you use the RC train base (which has a battery box and RC receiver built in). Having two motors gives a lot more traction, and putting on the newer clear traction bands on the wheels helps a bit more. It probably wouldn't be my first choice, but given the availability problems of the PF train motor, I'd consider it depending on cost.

[roamingstop]

You are comparing apples and oranges here. The emerald night carriages have newer 9V wheelsets which have far less friction. I wouldn't count on getting more than an hour with your 12V wheels. If you can fit the 6 AAs in, that's what I'd use.

Good point. I have a couple of old 12V wheel sets from old container terminals; I can add some boat weights to up the load and friction.

[martyboy70]

You are comparing apples and oranges here. The emerald night carriages have newer 9V wheelsets which have far less friction. I wouldn't count on getting more than an hour with your 12V wheels. If you can fit the 6 AAs in, that's what I'd use.

In regards to the RC motor, while it does get bad reviews, they mostly come from AFOLs who do train shows, they worked OK for most kids. I have a pair of them, and when combined with an RC base they make a very nice loco. The main disadvantages are the slightly higher connector which is not a problem if you use the RC train base (which has a battery box and RC receiver built in). Having two motors gives a lot more traction, and putting on the newer clear traction bands on the wheels helps a bit more. It probably wouldn't be my first choice, but given the availability problems of the PF train motor, I'd consider it depending on cost.

Hi I'm trying to do this as cheaply as possible so buying new bases etc. is pretty much out.

I think I am definitely swaying towards the AA option as the rechargeables I have were pretty much top of the range and are high capacity so it seems silly not to use them.

Why are the 12v wheels so much worse friction wise than 9v ones?

[peterab]

Why are the 12v wheels so much worse friction wise than 9v ones?

Different design, the 12V ones are essentially an axle in a hole, the 9V ones have a needle bearing. The 12V ones end up having a much larger area which is subject to friction, so more friction.

Edited August 28, 2011 by peterab

[roamingstop]

As promised Ive started the Apples and Pears test, using some Oranges and Lemons. The reason for this test is to find a 'conservative' estimate of how well the 9V PP3 solution can work for a modest train; and be backwards applied to older non-PF models. Im not using 'maximum speed 7' as this is almost too fast on the extended O-Loop - and I believe most KFOL's will be happy at setting 5, starting and stopping (which will be done every 15 minutes).

The locomotive is a modified 4512 running a PP3 9V Durcell battery; PF receiver, 8866 motor, older (lower friction) dark bley o-bands on the wheels. It is directly pulling two 12V cars from the 7823 Cargo Centre (my only 12V bits) and 3x4512 coal carriers. Interestingly... you can hear the engine speeding up and slowing down as the cars enter and exit the corners. Update once the battery dies.

Edited August 28, 2011 by roamingstudio

[Sokratesz]

hehe :)

Don't forget that the carriages from 7745 have 4 axles and are much heavier than the ones from 7823.

[martyboy70]

As promised Ive started the Apples and Pears test, using some Oranges and Lemons. The reason for this test is to find a 'conservative' estimate of how well the 9V PP3 solution can work for a modest train; and be backwards applied to older non-PF models. Im not using 'maximum speed 7' as this is almost too fast on the extended O-Loop - and I believe most KFOL's will be happy at setting 5, starting and stopping (which will be done every 15 minutes).

The locomotive is a modified 4512 running a PP3 9V Durcell battery; PF receiver, 8866 motor, older (lower friction) dark bley o-bands on the wheels. It is directly pulling two 12V cars from the 7823 Cargo Centre (my only 12V bits) and 3x4512 coal carriers. Interestingly... you can hear the engine speeding up and slowing down as the cars enter and exit the corners. Update once the battery dies.

Thanks again for this I do really appreciate it but I may have some bad news.

Last night on Ebay I did items by distance rather than time and found someone a mile from me selling the newer 6xAA box cheap so with the saving on postage giving me more to use to bid on it Im really hopeful of getting it(everybody cross your fingers for me)

So its looking more and more likely that I will be going down the AA route.

On another note me and my son have spent all weekend building the pile of bricks in the photo into their respective sets and we have both had a great time.

I'll get some photos up later probably in a new thread.

[roamingstop]

hehe :)

Don't forget that the carriages from 7745 have 4 axles and are much heavier than the ones from 7823.

Agreed... but this can also be valid for non 12V ;-). The axles on the old 4512 coal wagons are quite stiff; and pushing around had some pretty obvious friction.

That said, the 9V battery stopped (even powering the Locomotive) at around 85 minutes. I will let it cool down, and see if I can persuade it to give more output, but in the meantime it would indicate about 1 hour's play time for a middle of the run Lego train set. Not too bad, but definitely not in the same league as the rechargeable battery solution!.

[Sokratesz]

Speaking of battery boxes, hwow good is the lego-offered rechargable one?