Whats this guy up to?
May 24, 2002 at 1:17 am #9000
Looks like his is putting a largish capacitor across the motor, is he trying to improve the 3.0 motor? (He mentions B3.0 in the introduction).
Seems like a lot of work if its just to get a fat wastepipe
May 24, 2002 at 1:23 am #14028
maybe it is simulating what a cap does for your subwoofers in the car. it keeps the bass from getting soggy, which could be the equivalent in bit char terms as keeping the torque up on the motor. on the 3.0 which is made for rpm, this might give it more low end to get it going. is the word i am looking for called voltage? b
May 24, 2002 at 1:29 am #14030
It is common to put a capcitor across motor terminals. Must admit I’m not sure why. I think the capcitor charges up when the motor brushes are shorted across two terminals. Anyone know for sure?
I assumed the bit had a capacitor on the circuit board. Perhaps it hasnt, or perhaps the 3.0 need a bigger one. Might have to dig through my boxe’s, see if I have a similar cap.
May 24, 2002 at 2:03 am #14031
May 24, 2002 at 2:33 am #14032
a cap across the motor terminals usually cuts out interference. but in this case, i don’t know. b
May 24, 2002 at 2:34 am #14033
ok since i’m japanese, i’ll try and translate some main points. only thing is, i don’t know a lotta the fancy part terms so u’ll have to excuse me if the meaning is off. lol
anyways, he’s complaing cause his friend’s 3.0 motor is flying, while his is slow. so therefore, he’s come up with a way to add a “condensor” (spell)without the need for a soldering thing (lol forgot what they’re called st00pid me).
he went to his local hobby shop with 100 yen, and bought a 6.3V 100 ?F electric condensor. he saids that as long as it doesn’t hit hte ground, u canalso use a 10V or even a 16V.
on hte minus end of the wires, he put a cover on it, maybe around the same length as the antenna on the bit char-g. take off hte rear shaft, heat sink, and motor and face the front end to you. if u look at the area where hte motor used to be, there’s a small part of the gear shaftthat u can see from the side. using a small nail or something, push it 1mm~2mm to the side where hte gears are. that makes a small gap.
that’s it for the preparations. now he’ll put the condensor into the underside of hte chassis.
turn the car over (like in hte pic), behind hte rear shaft is a small square hole. put hte 2 wires into there and pull the covered minus wire up so it doesn’t hit hte shaft, then pull it onto the small gap that u made before (lengthwise, it should be just barely long enough). as for the plus wire, stick it into a hole where the stomach of the motor would be touching. it’s the gold colored piece that connects to the motor, any leftover lenghs of the wire, cut it. as for the small gap that u opened before, close it lightly with a small pench (dunno what it’s called in american…. lol forgot).
insert the motor and the shaft back in, and test it but be careful it doesn’t short circuit or something. as for the condensor itself, it will be hanging from the bottom of the rear, so tape it up to the chassis.
on a normal skyline body, the condensor is fine and won’t hit, but on the s2000 it may be a problem, so trim the body accordingly. sometimes it’ll look like a mega-huge muffler lol. and the clearance should be fine as long as it’s run on a relatively flat floor.
there you go. that took me over 20 minutes of my time. but it should be pretty much all correct. :smiley4:
May 24, 2002 at 2:58 am #14034
capacitors across motor terminalsactuall take electricity away from the motor (for a fraction of a second whenthat small)and store it to be used the next fraction of a second so the motor dosn’t take all the current at once.They call them startup capacitors. This way it evens the current flow out a little. Motors take double the current when starting thenwhile running which. And if a motor is held at a stop with electricy running throug it it will melt the windings. So the cap dosn’t allow it to do that on startup since the shaft is stoped for that short while. I tried a 100mf cap across my motor terminals of my 3.0 and it didn’t seem to make a difference so I thought exactly like b_drift and the car audio power Cap. Hooking it across the motor it won’t charge like a car one will. You’ll see the car ones are hooked right in parrellel with amps and are hooked up directly to battery at all times. The cap across the motor won’t do that since the motor is given power only when throttle is give. So I connected the top corner terminal on the PC Board abovewhere the motor wires go it. That’s also where the pos wire from the battery goes. Then I soldered the other wire to the emitter side of the transistor for the forward direction (third transistor down I think).I found the right transistor byjumping the transistor makes the wheels spin.Now the capacitor will charge at all times and dischargeto thetransistor when forward is pushed.This mod would help if themotor took more current then thecircutry could deliver on its own. (Just like the car where the amps take the current faster then it can get it from the batteryall the way back to the amp) But it didn’t make any difference. I have a feeling since the motor is so smallthat the circutry can deliver power just as fast as the motor can take it. You can’t make a motor take more current then it wants. You could hook up a hugebattery to the motor that was the same voltage and it wouldn’t spinn any faster and wouldn’t take any more current. A higher voltage would make it faster but then fry the motor.
Then I thought I’d hook the cap up to the terminals on the board where there’s already a cap thinking I’d add a little more capacity to that. But, again no difference.
Boy oh boy, I could ramble on about this stuff all day. I must be boring to listen to! Capacitor discharge, magnetic fields, motor current ratings … blahh blahh blahh. I sure hope someone is interested.
Anyway, I think I’ve hooked it up every which way I could think of and no change in performance.
Please tell me if any of you see different results.
May 24, 2002 at 3:10 am #14035
JP does it say anything about results? Maybe my car is fast like his friends and that’s why my cap mods didn’t work. I have a theory that these cars are made in different plants or something because my friends RX-7 is alwyas slower then my WRX when races with the same motors.
May 24, 2002 at 5:36 am #14047
wow….after reading all these posts, I really feel like digging out my Physics book I used last year to review all those electricity and magnetism concepts, cuz they seems very useful when it comes to enhancing the performance of my bit. Hey Peter, you are not boring to listen to, I learned alot from all your previous post, keep up the good work!
May 24, 2002 at 5:51 am #14050
nope i haven’t found anything about results yet…
May 24, 2002 at 6:16 am #14056
hey prabbit. so if your 3.0 is maxed and cannot take anymore juice. what about the 2.2 in the booster car when on boost. are they frying the motor since the booster runs a 2.2 faster than a normal bit char w/2.2? when on boost. my regular bit char’s performance actually gets “soggy” after a few minutes. my slow car w/ 1.0 runs decent for 3-4 minutes and then crappily for 2 more minutes. must be the battery being messed up. let me know. b
May 24, 2002 at 10:53 am #14077
Thanks for the translation. What about the other link, does that mention why they are doing this?
May 24, 2002 at 7:16 pm #14087
Couple of things this could “possibly” do. I’m in NO WAY suggesting that it does in fact do this.
1) reduce noise coming from the motor, this would allow the receiver to get a cleaner and more responsive signal from the remote
2) it might help with the stuttering problem that some 3.0 motors have.
3) It helps get rid of the initial spike from the motor starting up, giving you a longer run time
4) It could give a storage medium for when you let off the “gas” at which point the motor becomes a generator. This would effectively give you a slightly longer run time.
Feel free to dispute this and say it doesn’t work, as I have not tested any of it.
May 24, 2002 at 7:19 pm #14088
Well b_drift, here’s my theory on your question.
First of all, in the regular car the motors aren’t maxed out. The only take as much current as the need based on voltage. Ohms law is V=IR. R is the resistance or impeadence of the motor windings, V is the voltage applied to the motor and I is the current it will use.If the booster car adds more voltage, do the algebra, the motor takes more current. So, the motor’s aren’t necessarily maxed out, it’s just they won’t take any more amperage based on the voltage they are being given. So, if more voltage is given, more amprage will be drawn and more power made. Now, if too much voltage is applied, then the amperage will increas to where it will get hot and melt the brushes away. (Volts xAmps = Watts) and watts is directly proportional to heat. The more watts, the hotter. That’s right, do the calculation on a light bulb. 100 watt bulb at 110 volts means .9Amps is being drawn (of course it’s AC so a few other rules apply but close enough).A 100 watt headlight that’s 12 volts is 8 Amps.
My cars with upgraded motors did the same thing, soggy. When I put the NiMH battery in they lasted a LOT longer before getting soggy. I’m sure it’s the battery that’s to blame for this. However, running your stock battery down is necessary if you want top performance out of your battery but with NiMH you can regharge at any time without the battery developing a memory.
OK, so, I believe there are three stages of the battery power. Peak, Normal and Soggy. With regular NiCad and 2 charges back to back my 2.2 was aprox. 30seconds peak, 4 minutes regular and (depending on warm or cold) 1-3 minutes soggy. With NiMH and 4 charges back to back my 2.2 was 2minutes peak, 20 minutes regular and 5-8 minutes soggy. Now, I know you’re thinking, so what, longer run time. That’s not what’s so good here. I’ts the Peak Time that kicks butt.
I belive Peak time is simmilar to the boost button. Yes I’m sure the Boost button applies more voltage to the motor but I’m sure it’s within specifications of the motor. I think peak time right after a good charge on a regular bitapplies the same voltage as the boost button on a booster car. Also, the AC charger that I made peaks the battery a little better since it’s .5 volts higher then the remote. The booster cars probably have two transistors for the motor and one of them applies a higher voltage to the motor when the boost is pushed. This should be OK since the boost button is pushed once the car is moving. I’d be willing to bet the motor wouldn’t last as long if the booster cars appliedthe highest voltage at startup.
Have you ever given your bit throttle while on the charger? Have you heard how much faster it sounds? Well, that’s what a well peaked battery will sound like for the first 10% of it’s life if well peaked. I don’t think the remote chargers are very good at peaking the battery.
To prove it I made a jump that my normally charged battery couldn’t quite make it up. I’d give it a good running start and it would just about make it to the top. This was with a battery that was fresh but not at peak. The car ran like this for 20 minutes with the same performance so I knew it was in the normal power range of the battery. Then I put it on my AC charger for 2 minutes so it would get a good peak and tried it on the same jump. It went right over, no problem! It kept going over the jump for 2 minutes untill it went back to normal. Then it wouldn’t make it over for the next 20 minutes. NiCad batteries are the same only they have less capacity meaning all these times are cut in 1/3. Peak is only 45 sec and normal is only 6 minutes (assuming you charge well). Give this test a try. tell me what you think. Make a jump or hill that your car barely makes it over after trivnig your car for at least a minute. Then charge it back to back 3 times and dirve it over the hill right away. I’m sure it will go over! No imagine you had that kind of power for 2 minutes.
I don’t know how much faster a booster is then a bit. I don’t know how much voltage is applied. I don’t have one. Sorry. All I know is my bit (modified with NiMH, Blue gears, bullet motor andgear)is so fast it’s hard to stay in my track that’s only and oval on a 4X8 pool table and it goes over jumps that it usually can’t land because it gets so high and far the car bounces all over when it lands. I’ts too fast to race on a tight corse but great for drag racing.
May 24, 2002 at 9:49 pm #14096
Just one comment. I fairley sure that the voltage applied to the booster car motor is the same whther or not the booster button is pressed. The slower speed is created by using pulse modulation, power is applied to the motor in short bursts (every 100th of a sec or so), this gives the power of all the voltage, but with a slower speed. With the booster pressed, the voltage is constant.
Pulse Modulation is the stanrd way of reducing the speed of a motor without reducing the power. The reason the bit is loader without the boost, is because thats when the motor is being turned off and on very fast.
May 24, 2002 at 11:07 pm #14097
hey thanks prabbit. so is it the voltage or current that drops causing the soggy time? (it was 8 years ago when i was into stereos so i can’t remember) and what did the cap for the subwoofers keep constant for no soggy times?
so about the original topic, can we assume that the cap was not to cut out noise because they used a big cap when they could’ve used the tiny plate types?
so that leaves helping get a good charge or keeping up running performance or ??????
May 24, 2002 at 11:13 pm #14099
okay. since the cap is going from the bell to the housing, it cannot be for charging, so that leaves performance or ???? (looking for a cap to try this with)
May 25, 2002 at 12:21 am #14112
You can get this cap at Radio shack 100 mf.
Thanks Steveg. You’re probably right. I just assumed it was voltage regulated since the cheapest DC motor control that uses pulses that I’ve seen is $80. Of course those are for 1/16 hp motors too. But you’re right, pulses to control DC motors is the best way to go. Lower RPM with same torque ratings. I would have to hook up my o-scope to determine if those pulses were there since the voltmeter will probably show a lower RMS voltage instead of pulses.
b_drift. Current is directly proportional to voltage. When voltage drops, amprage drops. Completely linear equation V=IR (Voltage = Current X Resistance) The cap in cars keeps the voltage up, which any size cap would do but they use large capacities like 1 farad (in my car) to keep the voltage up longer when current is drawn. A.1 farad would keep the voltage up but as soon as the amp took a lot of current (bass note) the cap would give it all the current it had which would only be a fraction of a seconds worth. Then the voltage would decrease since the cap has no more stored energy until the bass note is gone and it can recharge. The 1 farad cap is large and keeps the voltage up throughout the entire bass note and then recharges when there’s no base. It’s just kind of a buffer.
May 25, 2002 at 1:21 am #14119
cool. so it should be acting as a buffer,so maybe with your ac charger giving you such a good charge, that may be why you saw no difference. i guess, i gotta give an opinion with a normal charger on a nicad batt. b
May 25, 2002 at 2:31 am #14128
Steveg is right! xsracer hooked a LED up to his motor terminals and it pulses on normal driving and is constant when boosted.
Good call Steveg!
May 25, 2002 at 2:46 am #14130
jmauldI agree with all 4 of your suggestions. It could do all of those! I didn’t notice any changes on mine but it could make slight changes that I wasn’t noticing.
But, anyway, great theories!
May 25, 2002 at 2:51 am #14131
all i could find was that the 6.3V 100?F condensor was put in front of the motor and on top of hte thing. anyways, it seems that the whole car’s setting was for drifting. sorry. but i believe it’s just an addition to hte electric input into the motor….
May 25, 2002 at 3:36 am #14134
If you would like to learn more about startup capacitor theory you can go to yahoo and type in: “starting capacitor” theory. be sure to include the quote marks as you will get a more definate search. Most of them are about AC motors but most of the theory applies to DC motors. The main difference isthe cap is placed in parallel instead of searies (I think).
Please, if anyone disagerees with anything I say, please post something. Some of my information is fact, some is educated guess. Please don’t take ALL my words as fact.
May 25, 2002 at 5:41 am #14144
I have a micro rs4 and browse through the HPIforum quite a bit and they are adding capacitors to thier esc’s (elecrtonic speed control) to get a “punch” when racing. They say it gives them a boost in acceleration. The idea is to have the ‘cap’ charge up and give off all the stored electricity very fast. So imagine you are coming into the turn and you let off the throttle and coast through. But while you were coasting through your cap charged up and when you hit the throttle you will get a pulse of electricity that is of a higher voltage. Many people have had good results with this on thier micro rs4’s. And if you think about it it makes sense. ie: you charge up a huge cap (size of a tin can) then touch both contacts to to a screw driver (or any other conductive object) and you have arc welded a cap to your scewdriver. Just a word of CAUTION using the wrong cap has FRIED electronics so be carefull. If you want a different explination you can D.A.S. in themicro rs4forum section at http://www.hpiracing.com/
Please take this info with a grain of salt (i could be (probably) wrong)
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