peterab

Be very careful for a while on your new bike. Changing bikes can be a significant risk factor. Each design will have it's own characteristics, and you being a relatively new rider will be accustomed to your first one. You might unconsciously expect your new one to handle the same way and get into trouble. If you are going on a long trip that might give you a good chance to get used to the new bike, but be wary of trying to keep up with anybody, since riding at the edge of your skill level on a new bike is also not good. Pre-plan places to meet up if you get separated instead so you know you don't need to hurry. Oh and have fun :-) Just in case he runs into someone intent on stealing a bucket??

Target have a toy section and they stock our favorite toy ... just saying :-)

I'm a bit surprised by this. My newer 9V wheel sets roll as well, if not better than my PF ones. They do tend to wear with use and roll less freely, but I'd imagine the PF wheels will wear out eventually too. Anybody else have any observations on if 9V and PF wheel sets differ?

Price per part, the modulars are hard to beat. The creator houses come pretty close though. Bricklink is a great source for bricks too, and since you can order individual parts better than whole sets unless most of the set is useful to you.

The difference is the 9V axle goes all the way through the plastic wheel, and has a pointed end, whereas the RC axle sits in the wheel, the pointed end being a part of the wheel. No real visible difference.

The problem is they are connected internally in the 9V motor. Without the modification power from the rails will power the motor, meaning you can't control it independently via the PF gear. The modification in effect separates the motor from the pickup circuit.

I'd add to that that TLG see the US as an extremely important market for future growth. Their biggest market is Germany, but it is in their opinion saturated. If I remember the figures correctly they were about 12% of the toy market in Germany. The US is a bigger market and TLG has a much smaller slice. They don't have the same strong tradition there as in Germany, where practically every child has some LEGO sets, and has had since the late sixties. The US is currently only third or fourth largest market each year, by keeping the prices low enough to build the brand support, TLG probably hopes to develop the same sort of brand recognition and market share in the US as Germany. Distance doesn't account for all the difference, especially since the Mexico factory doesn't make the full range of parts, so stuff gets shipped in all directions around the globe between China, the Czech Republic and the other factories. I can buy at US retail prices and ship here cheaper than buy domestically, despite the fact that bulk shipping for TLG would be much cheaper. RRP is the manufacturers recommendation, though I've seen different stores claiming different RRPs for the same product so I'm a bit confused by that. It acts as a guide to stores to let them know vaguely what they should initially set their price at to avoid a price cutting war which hurts retailers and the manufacturer. There are very strong rules against requiring a store to sell at a particular price, ie the manufacturer is not allowed to discourage discounting, or different retailers are not allowed to fix prices together. The only real limit is the wholesale price that is charged, and retailers can obviously check each others prices.

My train town consists mostly of a turntable and roundhouse. each is four straights long with a single straight track between, but as you'll understand once I add a couple of ovals of track around it there is little room for much else. It gets taken to train shows as part of a club layout and other members do more of the town scenery. I'd like to do a multi level layout, including a passenger station, and European town center, perhaps including a medieval portion. That will have to wait until I've finished renovating our house and have an extra room available to expand into.

Congrats Dr Rod on your announcement. I'll be trying to get to the first Brick Show. It's nice to see how friendly we all are, thanks for sticking up for Brickvention. Of course I guess we all like to attend each others exhibitions. I'm looking forward to BrickExpo and to The Sydney Brick Show, partly because I will be able to enjoy them without the work involved in running the event, but mostly because I'm on a crusade to have a stupidly unwieldy brick name badge.

I'm really looking forward to my first BrickExpo. Excellent speakers.

TLG rarely comment on this, but in the past they have said the RRP is set with consideration of the costs of a range of items in each region. They also have stressed that they view LEGO sets as a luxury item and price them accordingly. A few years ago at the beginning of the US financial crises they indicated that because they considered their future growth depended on the US market, that they would hold prices there artificially lower. I think there is a thread on pricing in the ambassadors forum that has a link to this. I've had discussions with one of the LEGO designers (I was ranting about Aussie prices :-) and he assures me the wholesale cost of sets to retailers is the same in almost all regions of the world, and the RRP is negotiated with the major local retailers in each region. The only places where the wholesale prices differ is where TLG are trying to grow the market. These two bits of information suggest a couple of things; It's probably not likely we will get equivalent pricing to the US unless the US prices get raised. Our local retailers are at least partly to blame if our prices don't compare to other regions of the world. If you can manage to get sets from overseas cheaper that's probably worthwhile. If this is just a trend amongst the AFOL community it won't make much difference, but if the wider community start doing it retailers will need to lower their prices to compete. Perhaps the local retailers have noticed that people only buy stuff on sale, so they have negotiated for higher RRP so their margins don't suffer when most of the stock gets sold at 20% off. That could work for them unless the 20% price is also unattractive.

I'm pretty sure hoeij has measured the 9V motor running with a 9V controller, still room for error due to the motor not being purely an ideal resistor but better than the situation above.

From a pure energy perspective I can't see that there would be any difference over an extended time period as long as the resistors have identical properties.

I think you're getting somewhere now. Method 2 is correct. I'll try and illustrate why with a bit of a thought experiment. I'll idealize a whole bunch of things for the purpose of making the illustration of how the PF receiver is operating clear. Later I'll try and address some of the other issues people have brought up in the thread. A thought experiment to clarify PWM Consider running your train motor for some fixed time period with the 9V controller output at 4.5V, say one minute, and for arguments sake lets say it makes 16 rotations around your layout. Now consider using a PF battery box to run to motor for one minute instead. Since a battery box only outputs 9V, the train will run twice as fast so ideally it will make 32 rotations. That's not really equivalent so we next consider using the battery box to run the motor for 30s and turning off the battery for then next 30s. Now we have the same energy usage, the same distance traveled, and over the whole minute the same average speed for both the 9V and PF case. There is still a difference in how fast and when the train travels in each case. To make the PF case more like the 9V case, we might like to turn the battery box on and off more frequently, and thus spread its movement more evenly over time. As an example lets turn the battery on for half a second sixty times during the minute, once each second. We still have the same energy usage, and in the ideal situation where the train reaches the speed one would predict from the voltage instantly, the same distance traveled and the same average speed. BY now you're probably thinking that I've made a bunch of idealizations and the poor motor is going to be heating up and screaming and jerking around, and you're sort of correct. It's not a problem though if we consider what the DC motor will in fact do in response to a rapidly changing square wave input. If we think about the shape of the velocity over time graph ideally it would be a nice square wave output, but practically the motor will take a bit of time to get up to speed when the battery gets turned on, and inertia will carry it on after the battery is turned of. In reality it will look a bit more like a smoothed off square wave. In fact the higher the frequency with which we switch the battery the more smoothed off it will look. In fact it will start to look a lot like you would expect the output to look like if you averaged the input over time, ie had a constant 4.5V for the whole minute, maybe with a little noise at the frequency of switching overlaid on it (thats where the hum comes from in PWM systems, since the frequency used is in the audible range). Hopefully you now can see how a train motor could appear to be powered from 4.5V but in actual fact be getting 9V pulses. Duty Cycles and speed control So far we can see how to get a train to move at half speed, but for completeness I'll illustrate a few more cases. Zero speed is easy, just don't turn the battery on. Full speed is also easy, don't turn it off after turning it on. How about quarter speed? If we agree that the DC motor will tend to react the same way to high frequency inputs as it would to their time average, any square wave in which the power is high for 25% of the time will result in quarter speed. Its called a 25% duty cycle because the power is on 25% of the time. It could be done by having the width of the on pulse from the 50% case, or you could keep the same width of pulse but just skip ever second pulse, ie turn the power on, off, off, off, on, off, off, off. I suspect the Lego solution does the later because the frequency of the noise the motor emits gets higher with speed as you would expect in this case. For three quarters speed any square wave in which the power is high for 75% of the time will do. I suspect Lego do something like on,on,on,off,on,on,on,off. Toastie's Friction Considerations So far I've very carefully avoided any consideration of tourque or friction and also of any losses in either the PF receiver or 9V controller. What I've described is the voltages at the inputs to the train motor and its response. Toasties viewpoint at this point might be helpful. If we consider the two cases of PF at 50% duty cycle, and 9V controller outputting 4.5V, we can see that they consume the same energy over the same time period. Thus we would expect they would give pretty much the same distance traveled from Toastie's correct observation that pretty much all the energy available at the motor will be used overcoming friction (it doesn't really matter for this argument if friction depends on speed or not since both cases are at the same speed). This doesn't account for any losses in either the 9V controller or PF receiver. Comparison of 9V and PF losses I think we all agree that the voltage divider in the 9V controller will lose energy (dissipated as heat). If 4.5V is reaching the motor, another 4.5V is being dissipated. This will be of the same magnitude as the energy used powering the motor, since similar current is flowing in both. The loses in the PF receiver will be whatever is involved in running the IC's for the pulse generation typically much less energy than for running a motor. Switching transistors typically use orders of magnitude less current in the switching input than the power input. There has also been some discussion of the energy lost to the hum in the motor. Since this is a noise (in the signal sense) artifact it should be plain that it would be poor design of the electronics not to minimize it, so we can expect it also to be a fraction of the useful output. Since the PF receiver doesn't ever change the voltage of the battery pack, there is no equivalent to the 9V controllers voltage divider, so no equivalent energy loss. Their will also be some energy required in running the communication with the remote, but given the limited range it will also be a different order of magnitude than running the motor. We can see that the expected losses are different orders of magnitude for the 9V and PF electronics, hopefully illustrating why PWM was chosen rather than a voltage divider for the PF system where battery life is limited. Other Considerations I think LT is confusing PWM for control of motors with switched mode power supplies which do something similar as far as I remember to control the output voltage. I want to be really clear that, if I understand the way the PF system works correctly, the only voltages being output from the PF receiver are 9V (or whatever maximum voltage the battery supplies to its input) and 0V, the speed control is via changing the duty cycle not the voltage. There may be PWM being used to encode the signal from the remote but this is entirely separate from this discussion. I think the observed 3-4 hour life of the rechargeable battery pack fits pretty well with the theoretical analysis and expected loses discussed above.

I think this is the key to your misunderstanding. The PF receiver doesn't do this, it simply controls the duty cycle, or percentage of the cycle the power is flowing. When current is flowing, the voltage is 9V, otherwise it's 0V. While the current is flowing it it being used to drive the motor, overcome friction etc, just like the 9V system. Consider a 9V motor running at 4.5V at 100mA, to achieve the same speed the PF receiver would need to power it at 9V at 100mA at a 50% duty cycle (ie for half the time). With the 9V controller the other 4.5V at 100mA is being dissipated as heat. There is no need for this with PF since there is no other large resistive load. Obviously this is an idealized description and there will be small losses in the receiver, some loss to the humming sound etc, but none of them are significant enough to be anywhere near the loss to heat in the 9V controller. The other components Brick Tamland mentions are required just to switch the 9V (or in fact whatever voltage the battery provides, ie 7.2V for rechargables etc) on and off, though as he correctly states the circuit will be designed to minimize losses. BTW I've studied physics, electromagnetic theory, calculus and scientific instrumentation and worked as a repair tech on an IBM motherboard assembly line.

Or perhaps I'll feel crap as you come here and show how much better you do it. Seriously though I find you planning and neat workspace quite alien, nothing like my piles of bricks on the carpet. I better explain at this point I'm 45 but have never gotten beyond building on the floor, I find it gives me more room to spread bits, which helps in the tactile way I build. Your Moc looks like it will be wonderful, and you should check out Holger Mathis' article on wide curves in Railbricks. I'm pretty sure you could use a variation with your 4.5V rails to at least test if you could make it run. I agree that the Maersk train from LEGO is one of their best, and if I'm not mistaken the designer was one of the AFOLs that worked previously on the hobby train set. I think TLG may be hiring AFOLs as a way to provide the sort of trains AFOLs like. Jamie of Emerald Night fame was also an AFOL before he became a TLG employee.

You sir, while being the least certain of your answer, are also the most correct. The PF receiver controls the speed of the motor via PWM, or pulse width modulation. The battery box provides a certain voltage (slightly different depending on type, ie 9V for 6 alkaline batteries, ~7.2 for the rechargeable etc.) and the receiver simply allows this through to the motor in different width pulses. The pulses are widest at full speed and narrower at lower speeds. The frequency of the pulses is high enough that the motor doesn't jerk but moves smoothly, though you may have noticed, there is a high pitched humming sound with PF trains due to the frequency of the pulses, the tone of which varies a bit with the speed of the train. If you power a 9V train motor with a PF receiver it will hum too, which shows it's the power delivery causing it rather than the motor. Since the current is in effect being turned on and off again there is no excess power to be dissipated like in the 9V controller. Modern DDC controllers for scale model railroads also use this method, partly to get away from heat dissipation problems.

I think this is a little unfair given the way most large retailers like K-mart work. Generally the staff don't know what definitely will or will not be coming until the truck unloads at their loading dock. They have very little storage area so try to minimise having any stock 'out the back'. They will sometimes tell you what they've been told to try and be helpful. Often what they've been told is unreliable. The lack of customer service is deliberate, but stems from the way the business operates rather than the attitude of the sales staff. It's one of the things that allow the large chains to sell cheaper than small toy shops.

If you want an affordable option for recolouring the carriage have a look for Dark Purple train windows on Bricklink. Purple and lime green are complimentary colours so while it might be a bit unusual it should look OK.

Paul, he's talking about the AAA battery box not the rechargeable one, he even gave the part number to be extra clear.

Well, the secret is in your own post, these were not post war (at least not the sub 40hp Kof I) they were a design from the 1930's. They were intended to perform light freight shunting duties at small stations, so probably a couple of cars at a time. The aim was to make them simple enough so they could be driven by normal station staff. They essentially freed up the engine of a mixed freight train from shunting at each station, thus cutting it's travel time. They are also quite small so they could be transported on flat cars between stations as their top speed was very low and would have created problems for other traffic if they had to be driven under their own power. That accounts for most of their odd looks. The later second series (which the prototype of this Moc was) had up to 130hp, and the third series up to 250hp. They were used extensively in post war West Germany as they were cheaper than the larger shunters to operate, mostly due to not requiring a fully trained driver.

Agreed, thats the 'more difficult' part I was referring to. Though Holger Mathis' BR80 proved it can be done well in even the smallest loco. I'm still struggling with powering my moc though

Well, I guess that puts me in the old bracket then, I'm 45. I was 28 before I got my bike license :-)

Another option is to use this battery box, which would allow you to build a more detailed tender. The real drawback of the 4.5V system is the small wheels which make your engine look more like a freight engine or shunter since steam passenger engines had larger driving wheels so they could reach higher speeds.

Australia is a special case since we have no LEGO stores. Making world wide generalizations based on what happens here is not far from misinformation.