Marxpek

@LXF I oversaw something here... your battery is protected itself... it has probably the same protection built it... and that might kick in here and still provide enough power for the lights, still not prooving anything, all those damn safety-precautions ;D maybe attach a other motor which you do not stall in stead of the lights? that should draw alot more power then the lights (as far as i know the thermistor never really full breaks the circuit just raises the resistance a lot, but correct me if im wrong)

This is creative, but but I do not agree, you are placing a part somewhere that was never intended to have any parts, even worse, you are blocking a safety measure, especially designed for that purpose, so i do not consider that 100% Lego (solutions), since TLG will never approve this.

It doesn't not need a lot of current to burn your fingers ;) can you attach a wheel or something to the output? when you can trip the thermistor inside the buggy motor that would mean the battery delivers enough power. (but you will need a shunted box, but since you suggested it, you probably have one) These 2 do not really combine ;D

@TechnicSummse and of course removing thermistors is cheating, but i still do not believe 9v batteries can power a buggy motor..

What is the discharge rate on these? they say "high drain" but how high is that? Compared to a normal 9V battery anything over 200mA discharge I consider highh, but a 1000mA is not nearly high enough for a buggy motor. But when i look at the "normal charging time" on the battery that is pretty slow, and this normally correlates to the discharge rates. does it give a fast charging time for it and a C-rating? can it trip a thermal resistor when stalling a motor? Of course you are still only getting 8.4 volts from them, lowering the speed on the motor and also lowering the current being drawn. @LXF and somewhere you are being scammed with the info they provide, there is no way in hell this battery can contain 2000Mah @ 8.4v, most (trusted) battery brands have a value of 150mah up to a maximum of 500mah, my guess is they did some fancy numberwork here and you actually have a 285mAh battery at 8.4v. They went creative with numbers and most likely did something like this: 7 cells @ 1.2v each with 285mah = (7x285mah) 2000mah.. Did you ever do some measurements on these? it is highly unlikely that they will contain the same energy as a battery box filled with rechargeable AA batteries of the same quality..it is just a size thing..

this is not how a thermistor works, it has a certain setting, lets say a 1 amp thermistor will pass through any current up to 1 amp, if you go over that it will kick in within a second or so, but if you pass 500mA it will never kick in, a thermistor should always kick in within a few seconds of overload to prevent melting wires and shorting/burning wires. The previous best (tested) batterybox can pass 800mA, will trip the thermistor within a few seconds when attaching a buggy motor with some load, there are small differences in the thermistors production making some go to 900 mA and others to 700mA. The newer AA batterybox with the brighter green led, has a higher setting then 800mA, but this has not been tested for exact data yet (as far as i know), but from my own experience: one new batterybox can still not fully power a buggy motor, there are reasons the buggy motor was discontinued, this is one..

Hey @TechnicSummse welcome here ;) this box has one of the worst thermal protectors around (kicks in very fast), this has a older version of the thermal protection, a plate that bends when hot, breaking contact. Since i already know what you want to do here: i will say it again, buggy motors can ONLY be powered fully by the rc-unit, nothing else can bring out their full potential (unless you cheat with the thermal protectors) not even the battery boxes that came with the buggy motor expansion pack or the yellow batterybox (like on 8421) can handle the current needed. Besides that: 9 volt batteries that can deliver that kind of current are rare, since they are moslty made for low power consumption.

My first word upon opening this topic: "Whaaat!?" my second word: "Wow!" Welcome here, that is one hell of an introduction ;D

It really doesn't, keep in mind that the action cam is low to the ground so it looks a lot faster, with the action cam on it it becomes unstable, so i never went over 25km/h with it attached, it takes about 150-170 meter before it reaches top speed with the gps computer on. it is a bit over-engineered to prevent destruction with every crash so it is a bit on the heavy side. Sometimes it already gives me troubles with the thermistors in the motors, needing them to cool down. what exactly do you mean by this? how fast the wheel could spin in theory? (Philo's info again) fast output= 1700 rpm geared up 2,5x= 4250 rpm without load. 107mm diameter wheel: theorectial speed: 84,7 km/h... But with 35km/h it should be something like 1740 rpm that was actually reached. Hmm, i doubt i reached the roof on this, i went about this the raw power way. the next build will be more about finesse and lightweight construction, risking total destruction upon the inevitable crashes.. Gotta keep pushing further ;) first with more finesse, or maybe later ill just add more motors :D.

Well here is the final result: Not much besides some weight reduction has changed, but my camera setup has been expanded with an action cam giving some nice footage here. The video does the talking, i'll shut up...

Since we are discussing this: does the boost system has to be on the car? i mean can we build a static launch system at the start line?

I wouldn't mind if you got a late entry, but looking at the letsbuilds post from 2 juni: i guess not..

I thought you said this was just a concept? i do not think the rules should be adjusted to concepts that were made ahead of the rules, especially when you are warned for this... (I do not want to sound harsh but this was the risk you took when building too soon)

Great to see this! looks well thought trough. 2 questions: what is excluded here? I am not familiar with the term classical steering. Inner radius i suppose?

My guess is that @letsbuild is waiting for the voting system to be fixed.

I love this design. Nice work!

I will take out the rc steering and use bigger wheels, maybe i will try suspension, but my guess is this will only amplify the effects of vibration. And i will try to make a decent bracket for my phone. would be nice to get it working, but it already works ok with the action cam. I will have to check if i have a new version available.

Thanks for that idea, i had the same, but i am not happy with it. i used a similar solution for my phone in this video, but the problem remains, the lens is off-centered or the turntable is unbalanced, that does not matter when you are just using it as a dolly, but when panning the lens is off centered. I did not use any rubber bands yet since i am not happy with the position of the lens in the bracket yet, this has to be fixed first before fixing smaller issues.

Hey everyone, in my quest to get better video shots without investing money, i decided to make a motorized dolly from pieces of Lego i have and rarely use, as you can see, i do not care for its looks, just the function. it can just drive as a dolly, pan at 3 different speeds while driving, or just pan when you set it on 2 bricks. The dolly works good on a smooth surface and has about 240 degrees of unobstructed view while panning, even with the most basic Lego mount on top of the turntable my phone did a decent shot. (phone wedged between the green lift arm attachment shown in the video) it is still a bit shaky but a better mount might fix that, it was made for a action cam in mind, which is lighter and more centered on the turntable, giving better results. The rc car unit is not needed but it comes in handy since it will allow for speed control with the built in IR-receiver, it could also be made with a frame and a single motor. The rc car unit has a hard time steering this weight, but it can be done, for even more movement in a shot, the shots in this video are in a straight line while panning. i know bigger wheels would give a more stable ride, but then it wont be able to steer with this unit, but i will probably give it bigger wheels anyway. If anyone has tips on how to mount a phone on a turntable, i would love to hear. My biggest issue is that the lens on phones is at the top, or to one side when you hold it sideways while filming. If you want the lens above the turntable (for true panning) the whole thing becomes very unbalanced, giving shaky images during panning, since the turntable is causing more friction. Of course any other tip is welcomed as well.

@zuxLooking into the gps data on the 32,71 run, that went slightly uphill, 1% gradient. so i'd be better of riding the other way ;)

@zuxI have only done 3 runs yet, on a flat (like the most of Holland) asphalt road here : https://www.google.nl/maps/@52.497985,6.1206633,20.25z?hl=en 2x in one direction and 1x in the other, 28,9km/h , 30,9km/h and the last 32,71km/h, so the answer to your question at the moment is 30,9 km/h. But i will try to push it further and i will do that in both directions while filming it from my bike, i will also include the full gps data from the bryton gps computer, which will show speed-data, the track, elevation of the track and much more, but i am waiting for some spare time on a day without rain, which rare here at the moment.. I will update the topic soon with some more detailed pictures of the car, i did some weight reduction, its not pretty, but that's not my goal.

Good example with my record racers: - 28,47 km/h with 2 buggy motors and geared up 1:1,667, versus - 32,71 km/h with 4 buggy motors geared up 1:2,5 (for now, it is a WIP), but in this case i had to add a lot of weight in the form a 2nd rc-unit (battery box) Not by far linear results. Consider that the axles will spin at insane speeds within its brackets, causing a lot of friction, grinding parts down or even melting them, especially when using smaller tires (they need more RPM for the same speed) Please let me know how this works out with the new battery boxes, but (i took this from Philo's page on motor specs) a stalled L-motor can draw 1,3A, that is probably more then 1 box can handle, old boxes could handle around 800ma, i do not know what the new ones can take. Surely you will not stall the motors, but without load they already draw 120mA, and gearing them up will draw a lot higher current from the boxes, multiply that by 3 in your case.

like i mentioned, the process is fun and it might work anyway, but i like to know all details before i design, so i can design it the right way from the ground up based upon the set rules, The type of track is most important for me here, for example: what if you design a low body car and then there is a speed bump added to the track, just to make it more challenging? or maybe the car has to do a hairpin turn on a 40 cm wide track, maybe that track is 60cm wide and doesn't have a hairpin, many more variables, influencing (my) design. I'm not saying you should not build and design, far from it, if you enjoy it, do it! Only saying that I will wait for the rules, until then i will be working on another project (inspired by this)

I really do not understand why so many people are already designing and building, we have no idea if and when this contest will start, let alone what the rules will be, you could be building something that is not allowed in the contest later on... (still a fun process of course) I see people are eager to participate here, but patience might be best until the rules are set?

@Aventador2004 thanks for that info. @Zero (Zblj) that means that wheel would "only" be 65% bigger in circumference, meaning it would still need gears to reach similar speeds, not to mention the increase of the frame and weight. i think i will pass, fun idea though! ;)