Streets Car with Electronic Flywheel Runs Very Smoothly (Long - pics, video)

Lee; I'm sure that if anyone can solve this problem it will be you.

Looks like a great idea.  I might try that on some of my tiny motorized stuff for standard track.

For directional control, I'd probably just use two supercaps with diodes to protect the unused one against reverse polarity.

Lee - I will have to share your results with another train friend/engineer that has an excellent SuperStreets layout.

Art

That's what I was just thinking{though I'm electricly challenged, but I get brave hanging around John}...I'd liken it to a reverse lighting set up per given track polarity- the diodes would only allow working in that direction- now for the way to charge them even though they'd be off, for use when you need them{no 5 sec pre-charge}...John...any ideas?

Getting brave here- John, could both directional packs be simultaneously charged when ran in either direction, but only be used for a given direction via diodes...maybe a bridge rec somewhere in there....

Lee- YOU ROCK WITH THIS IDEA!

JOHN - Ok, jumbled mess in my head that it is- is there a way, per given track polarity, to use one pack and charge the opposite polarity pack, but, not use that 2nd pack unless the polarity changes...then they'd switch roles-use vs. charging - Is there a micro component that can sense polarity to do this?  I'm thinking "other direction" voltage pack would be piggybacking off of the "use" pack, but flipped voltage input to chrage it - then flip when the track polarity changes...can the packs be wired or switched in one end and be used out the other...?{can you tell why I'm not an electrical engineer}

You're over-thinking the idea.  Since you'd typically be running for a period of time in one direction, just let them charge when you're in the proper polarity.   Hopefully, you won't have to use them the instant you start up!  You might need a small (10 ohm resistor in series to limit the load presented on the track.

I don't think you need any resistor with them.  At least for those I played with, they have such a high internal resistance - more like a battery than an electolytic capacitor, that inrush current is quite tolerable.  I also don't think you have to worry about reverse voltage hurting them, at least up to their voltage rating.  

I have ordered a wider assortment of supercaps to test more, begin to convert, and play with in other ways.  I plan to do stress tests on some (will 24 hours at a steady reverse 5.5V ruin one, etc.).  

I'm not sure why, but I ordered a 25 Farad, 5.5 V one that ought to fit in the WBB panel van.  When fully charged it ought to "ride in through" about t going to see what happens. 

25 farad?  That must be a pretty healthy sized cap!

Yeah, its about the size of a C cell battery, according to the technical info.  Should fit inside one of the 'Streets vans, or I might try in a bus.  I'm having fun playing with these things and want to study different types, etc.  Really interesting devices.

Lee, thanks for the really interesting and enjoyable post.   I appreciate the thorough investigation!  Ken

Lee,

Looks like you solved the speed and stutter problem on your street's vehicles.  I just received the KA2's that I order from TCS for my DCC decoder equipped vehicles.  Will let you know how they work.

Larry

I look forward to future results.  Lee, you certainly do pick interesting topics to research, this one is a winner!

Lee;

Excellent idea and application.

While I don't run Superstreets yet, I don't know why this did not occur to me.

I use large electrolytic caps in my Robots to fill the current droop when the movement motors kick on and it makes the batteries last longer as well as making the robots run much more robustly. I put the caps on the battery side of the H bridges so they are always charging if the robot is on. Basicly in parallel with the batteries.

Supercaps as you noted have much higher ESR and would not work as well in my use but for your function they are excellent.

They are also far smaller physically for the given capacity. I only get 2500uF in roughly the size of your 2.5F one. Mine being a cylinder of course.

Thanks for the kind words and interest, John.  This is perhaps the most technically exciting thing I have worked on in some time.  I am learning so much, and expect to learn a lot more, much of it no doubt through mistakes and things that don't work. 

Anyway, I've now ordered about fifty additional supercapacitors of various sizes and types, included two more 25F  puppies (I want to see what happens if I put them inside some two-motor locos).  There seem to be two very different species- different materials or processes on the inside.  I ordered two 1.5 Farad, 5.5 Volt supercapacitors, one with a .16 ohm ESR (equivalent internal resistance) and one with 30 ohms.   ESR is not internal resistance, i's measured instead at 1 kHZ and thus something of a proxy for the impedance during quick energy release, I think.  But it indicates that while both should hold about 20+ joules at 5.5 volts (about 3-5 seconds of 'Streets vehicle full power) one might release all its energy in as little as 2/3 second while the other would take a leisurely 26 seconds.  I've also blown the train budget wide open by ordering equipment I should have long-ago bought for my workbench - calibrated power supply with digital meters and a small oscilloscope, to see more of what I am working on.  

It's interesting, you know a lot more about the supercaps that I do at this point.  I didn't realize they had such varying ESR ratings.  I like the idea of using these in some of the really small stuff like speeders that sometimes stall on switches.  I think I'm going to do some experimenting as well.

Last year I bought myself a digital scope so I could work on some of my projects, the old analog one just wasn't getting it done.  It was only $330, so I figured it was worth the investment.  It's an ATTEN dual channel model.

I'm curious as to your comment about not worrying about reverse polarity.  I'd think these would be particularly touchy about polarity.

I found the "Application Guidelines" on digikey, interesting and informative read.  Looks like overvoltage will shorten their life fairly quickly.  Also, if they were going to be operated reverse voltage I would definitely diode protect them.  Will shorten their life otherwise.

Interesting thread.  I would like to see your tests done with a series setup to see where the sweet spot is for size.

I wish all the clocks in my house had these, none do.

Dan

Well, keep in mind that six of the ten I was playing with didn't last the day!  I read in places that reversing polarity is a bad idea, in others that it isn't necessarily.  I know it did not harm them when I tested operating them at reverse polarity. But I did in only briefly and just to voltages below their rating.  I keep coming across words like "sustained' and "continuous" everywhere I see warnings aobut over and reserve voltages.  It seems to be like it would be prudent to install a diode to prevent reverse polarity.  But . . . realize that current has to flow into (for charging) and out of (the whole purpose of it) for a supercap to be useful, which means you can't put a diode on it.  I'm still getting my arms around that.  

Right now, I intend to leave the rectifier in the cars I convert, and simply install a 1.5 or 2.2F cap across the DC terminals of the motor.  The rectifier will protect against any reverse polairty.

The WBB sedans I have actually run fairly well at low speeds with no modifcations. Am using a Z-4000 transformer, don't know if that is helping or not.

Low speeds may mean different things to different people.  I think the six I have now are typical: with very clean wheels on clean track they run smoothly and dependably at just over 40 mph at about 6-7 volts, which isn't fast, but not as slow as I want, either.  I want much slower, and as I said that means lower voltage, which creates a challenge with connectivity.  None of mine will run smoothly at 20-25 mph (about 3-4 volts) smoothly for long periods.