Electronic Flywheel

[bertiedog]

Right, there is another unit, the Power One, which is detailed here:

 

http://www.lenz.com/products/decoders/currentdecoders/power1.htm

 

However it has some restrictions, offering as per Lenz's table of figures, one second of power at 250ma, very low power, but will sustain movement for that second until power returns.

 

250ma,(quarter of an amp), is quite low for a loco at medium speed, most would be 500ma, and the sustain period will be about half a second for that drain.( The Lenz table gives the figures for each current drain).

 

The best situation would be a small loco, with light load, and below 250ma drain, quite possible with a Mashima motored loco and 125ma is typical for low load at modest speed, so it will last for about 2 seconds.

 

This meets the bill for DCC, but can't be transferred to DC easily. It would need a PIC or stamp processor and control circuity to function, plus a capacitor of high voltage rating.

 

Quite how Lenz derive the higher voltage from a low voltage is unknown to me(It is patented), but at a guess they generate a high frequency AC signal, and send it to a swtched power supply transformer on the power board to raise it to 12 volts from the 3 to 4 volt capacitors that are made in these values.

 

If a very high frequency is used the transfomer can be tiny or even eliminated, and it is quite feasable to get it into the space.

 

Sorry if this sounds complex, it is!!

[bertiedog]

For smaller scales you need the Power 1 module not the power 3

http://www.lenz.com/...ders/power1.pdf

 

andi

 

Answered whilst reply was being researched very carefully indeed!!!!

[bertiedog]

Designing a circuit to work on DC with the operation of the Power One would be feasible, but it would be a complex and potentially expensive circuit, the components alone would come to more than the DCC units, the cheapest item would be the super capacitor!

 

• So back to reality, fit a flywheel...........

• Or use DCC, and it's got to be a Lenz system, unless other makers enter the market with other designs.

• Or design a DC powered Computer chip controlled power unit small enough to fit 00.........

Stephen

[bertiedog]

For smaller scales you need the Power 1 module not the power 3

http://www.lenz.com/...ders/power1.pdf

 

andi

 

What happens when a chipped loco ( Lenz) is used on DC, which it can, with the Power One (or Power 3) is still wired in place??????

 

Does the sustain circuit still function and deliver the PWM power?

 

This might possibly be a practical option for DC operation if it still functions, take a DC loco chip it, and fit the power one chip, and if , and it's a big if, it works it would act as the same electronic flywheel as with DCC.

 

Andi, have you any idea if this works, or is the Lenz Power One shut down without the DCC standing voltage to start with.

 

Stephen.

[bertiedog]

Further research shows the Gold chip shuts down without the DCC signal present, as stated by Lenz but this is the very situation that the Power One covers!

 

I think what they mean is that the system needs to be on DCC to start the process, so DC operation is out, but it defies logic somewhat, and maybe the sense is lost in translation from the German technical manual..

 

Stephen.

[bertiedog]

Right further research and email, and phone calls... The Lenz gold chip and Power One work on DC , as long as the DC has exceeded the 5volt minimum during that operation, giving the capacitor a chance to charge.

As the DC stops and returns at the same value, there may be a slight jerk as power comes back, as there is no feedback to the controller unlike DCC.......

 

So there you are, there is an electronic flywheel, it has to be Lenz, with Power one or Power two.

 

The table of currents and times remains the same with DC as with DCC no change there.

 

The only change is at crawl speeds if the DC is low, then the Power One is outside it's limits, and may not work, if the loco has just been used at a higher speed it will work at crawl, but only once, it cannot re-charge unlike DCC at the lower DC voltage.

 

I have checked all of this with experts and an NMRA expert. The Power One is not compliant with NMRA as such, but needs no compliance as it is extra to the chips basic DCC functions.

 

Stephen.

[Ron Ron Ron]

.....and it's got to be a Lenz system, unless other makers enter the market with other designs

.....So there you are, there is an electronic flywheel, it has to be Lenz, with Power one or Power two.....

Power one and Power three (not two).

 

The famous Lenz USP test is to run the loco off the rails onto a sheet of paper and it keeps running.

 

Zimo also provide a similar facility on some of their decoders. All you add is a suitable capacitor; the circuitry is already in place on the decoder.

 

 

 

[bertiedog]

[/b]

 

Power one and Power three (not two).

 

The famous Lenz USP test is to run the loco off the rails onto a sheet of paper and it keeps running.

 

Zimo also provide a similar facility on some of their decoders. All you add is a suitable capacitor; the circuitry is already in place on the decoder.

 

 

 

 

Zimo don't seem to have published figures unlike Lenz, but from a trade contact I understand it delivers less power than Lenz, meaning more confined to modern motors, which you would expect to be used on DCC, and lets not forget the original poster was hoping for a simple answer on DC, which clearly does not work.

 

The DCC answer is as usual at a price and a considerable one if you just want this feature....and this feature is not a cure all for bad track and a mediocre transmission....to get good running it just needs a sound design and build, and sadly we still get old fashioned " house" designs used and bad assembly making some modern designs unreliable.

[Baby Deltic]

You could fit a bridge rectifier across the pickups on the loco, so the capacitor is always charging on the correct polarity, regardless of the polarity of the track current. As far as reversing the motor under capacitor discharge, that's a bit more of a tall order. Obviously, its more than likely that DCC uses an 'H' bridge circuit to control the motor, so there is no direct connection between motor and rails, and the bridge is fed with DC on a single polarity. Reversing is done electronically by switching transistors on opposite diagonal sides of the bridge - the motor is in the horizontal bar of the 'H'. You still have the problem of motor polarity, however, if you choose to try a non DCC approach.

[CullingworthGNR]

Thanks for all your replies - it seems like DCC would be the way to go for this, to keep things simple!

 

Cheers guys

[Pacific231G]

I'd still be interested to see how a flywheel could be fitted to a Lima pancake motor.

As an aside, if having a flywheel fitted motor installed in body of loco (not connected to wheels) and wired in parallel to drive motor, on loss of power would this motor then provide a source of power to drive motor until power regained? Probably twaddle but just a thought.

Puck

 

It's not twaddle at all Puck. It was developed by Bob Symes as the "free motor" and described by him in the January 1961 MRN. Several other modellers tried it and I'm looking at an article from the March 1969 MRN by Michael Walshaw of MERG. It was more for simulating the behaviour and to some extent the sound of a diesel powered loco or railcar with the free motor alone ticking over at very low power settings until the controller was opened up when the traction motor would start to receive power and the diesel loco or railcar would gradually pull away in a more realistic way emphasising the difference from the beahavour of the more familiar (in 1961) steam loco. It was also supposed to supply some inertia to make for smoother running. In principle of course if the free motor was also a good dynamo a hefty flywheel could provide a great deal of inertia rather after the fashion of a Parry People Mover

The potential problem that Walshaw saw with the basic circuit with the motors in parallel (possibly with a resistance in series with one or both of them to tune their starting characteristics) was that the free motor being unloaded would tend to race away at very high speed and probaby not last very long. I'd have thought that a large enough flywheel would limit this but Walshaw came up with a rather complex circuit involving a diode bridge to control the free motor's speed. I suspect the attraction of the free motor was really more about the chance to play with interesting circuits than with its actual benefits but it might be worth looking at. The controllers at that time would have been simple rheostats so I've no idea how a free motor equipped traction unit would behave with a modern DC feedback controller.

 

I could also imagine (but not devise) a circuit in which the track voltage via a transistor (and a few other components) allowed current to flow to the motor at the same voltage from a small 12V battery set up with the control circuit slow enough acting to iron out tiny interruptions of power. Mind you DCC (or better track cleaning ) would probably be a lot easier as you'd also have to organise a charging circuit and make the whole thing bi directional.

 

David

[Baby Deltic]

I'd still be interested to see how a flywheel could be fitted to a Lima pancake motor.

As an aside, if having a flywheel fitted motor installed in body of loco (not connected to wheels) and wired in parallel to drive motor, on loss of power would this motor then provide a source of power to drive motor until power regained? Probably twaddle but just a thought.

Puck

 

Here's a 'fag packet' sketch of how you could probably connect a pancake motor across a capacitor as an 'electronic flywheel' (provided you could find a capacitor with a voltage rating and capacity compatible with your aims).

 

 

The motor would need to be disconnected from the pickups and the circuit hooked in. (The circuit controls the motor direction via a transistor bridge, but the track current controls the speed). Basically the bridge rectifier maintains a single polarity across the capacitor, regardless of track polarity, as the capacitor would probably be polarized, and go bang if it were reverse biased. The problem now, is how do you reverse the motor, if the current is always in one direction? The bridge circuit is used to reverse the motor using pairs of transistors. But how do you control which transistors are on at any time. Obviously if you reverse the controller, you want the loco to reverse. There are two opto isolated transistors connected across the pickups in opposite polarity to each other, so the bridge transistors are switched for the correct motor direction.

[Baby Deltic]

How does that work then?

Take an example. Power is applied , the opto's conduct ( in one direction dependant on polarity) and one pair of transistors in the 'H' bridge conduct so all is well and it works ( with careful component selection).

Now cut the power - instantaneously- like going acrosss a 'dead frog' in points , the opto's cut off instantaneously, the transistor bridge switches off, and isolates the storage capacitor , which is now on the dead side of the bridge from the motor's point of view.

Just how do you get flywheel action?

 

Good point. I did say it was a fag packet sketch. Five minutes of thought involved;) The opto's pose a problem, but if you connected a capacitor between the emitter of each opto transistor and DC ground, and a resistor between the its emitter and the bases of the bridge transistors to allow the capacitor to charge without being shorted out, the capacitor could probably charge enough to be able to slowly discharge via the resistor, into the bridge transistors and sustain them in conduction until the flywheel capacitor is exhausted. You only need about 0.7 volts to hold the transistors in conduction. Just surmising<_<

[Pete the Elaner]

Holy unreliability! That sounds complex.

High current circuits (1-1.5A) require more unusual & expensive components than the common components stocked in Maplins.

 

Sounds like a mechincal flywheel may be a more acheiveable solution or, dare I say it, DCC?

[Baby Deltic]

Holy unreliability! That sounds complex.

High current circuits (1-1.5A) require more unusual & expensive components than the common components stocked in Maplins.

 

Sounds like a mechincal flywheel may be a more acheiveable solution or, dare I say it, DCC?

 

Most medium power transistors can handle 1.5A without breaking into a sweat.

[Pete the Elaner]

Most medium power transistors can handle 1.5A without breaking into a sweat.

 

How many do you need. Looks like 6 in your circuit diagram.

How big (physically) is the cap you need?

Will that lot fit in a OO loco?

How long would it take to create & fit the electronics?

 

Still think DCC would be easier, cheaper & more reliable.

[Baby Deltic]

How many do you need. Looks like 6 in your circuit diagram.

How big (physically) is the cap you need?

Will that lot fit in a OO loco?

How long would it take to create & fit the electronics?

 

Still think DCC would be easier, cheaper & more reliable.

 

I see your point Iain. If you have the money to chip all your loco's and buy the DCC controller, then OK. I didn't say it was going to work, although it should in theory if you can source a suitable capacitor- That's the hard part. It would probably fit in a Limby diesel chassis with room to spare, circuit board wise, but again the capacitor size is the constraint. If your loco collection was as big as mine, you'd think twice about DCC, as good as it is. I personally have no desire to fit an electronic flywheel to a loco as I use electro-frog points anyway, although it would be tempting to knock the circuit up for play purposes. The original OP was 'can you fit an electronic flywheel on DC'. I've just tried to come up with and answer in non-DCC terms. Not easy, granted.

[Pete the Elaner]

I agree that in theory it is achievable.

I think the initial idea was for a cheap, simple solution to re-motoring with a physical flywheel. A workable solution seems unlikely to meet either of these criteria.

 

I'm not going to preach DCC here. Wrong place.

[bertiedog]

It's not a complex as you think, just protecting the capacitor and dualing up the circuit will do for reverse, but the problem is no such capacitors exist that can stand 20volts,(needs a safety margin, maybe 15v would do), and for a few secs like the Lenz, say 2 secs, it would need about 4 farads, please note FARADS.........

 

This is Whopping, hundreds of times bigger than the largest audio power supply capacitors at about 10000μfarads, and the voltage rating of a 4 Farad is about 3 volts only.(1Farad equals 1,000,000μfarads).

 

Some 2 to 3 farad capacitors are very small and low 2 volt rating, and it appears that you could stack them to get a 12 volt string, 6 in series, but it is now 1/6 th the capacity (4,000,000/6 equals 666666μf) BUT SEE BELOW.

 

Also these super capacitors have a few hidden rarely mentioned limitations, (you don't get a free lunch!!!)

• You cannot string them together more than three without voltage balancing circuitry,
• Putting them in parallel is not on, they discharge into each other, again without special protection circuitry.

We are back to the start, capacitors alone or with simple circuitry do not work, but with complex DCC control they can.

 

There are commercial systems using these ideas for buses and commercial vehicles running on electricity, but the capacitors are huge, about a ton or more each!!!

 

Stephen.

[Baby Deltic]

It's not a complex as you think, just protecting the capacitor and dualing up the circuit will do for reverse, but the problem is no such capacitors exist that can stand 20volts,(needs a safety margin, maybe 15v would do), and for a few secs like the Lenz, say 2 secs, it would need about 4 farads, please note FARADS.........

 

This is Whopping, hundreds of times bigger than the largest audio power supply capacitors at about 10000μfarads, and the voltage rating of a 4 Farad is about 3 volts only.(1Farad equals 1,000,000μfarads).

 

Some 2 to 3 farad capacitors are very small and low 2 volt rating, and it appears that you could stack them to get a 12 volt string, 6 in series, but it is now 1/6 th the capacity (4,000,000/6 equals 666666μf) BUT SEE BELOW.

 

Also these super capacitors have a few hidden rarely mentioned limitations, (you don't get a free lunch!!!)

• You cannot string them together more than three without voltage balancing circuitry,
• Putting them in parallel is not on, they discharge into each other, again without special protection circuitry.

We are back to the start, capacitors alone or with simple circuitry do not work, but with complex DCC control they can.

 

There are commercial systems using these ideas for buses and commercial vehicles running on electricity, but the capacitors are huge, about a ton or more each!!!

 

Stephen.

 

That's the thing, Stephen. Big farad sized capacitors aren't designed to power 12V motors, they are more for low power memory systems. I think extra pickups and wiring through a permanently coupled match wagon would be an easier proposition if you don;t want to go the DCC route.

[bertiedog]

This one way of using large capacitors, constant on lighting for coaches and locos, but no reverse, so it could not control a motor, and the motor would have to run on 2 volts at about 5 milliamps, something only a coreless type could approach.

[melmerby]

That's the thing, Stephen. Big farad sized capacitors aren't designed to power 12V motors, they are more for low power memory systems. I think extra pickups and wiring through a permanently coupled match wagon would be an easier proposition if you don;t want to go the DCC route.

 

1 Farad 16V capacitor:see here

 

But it is huge!!!

 

Keith

[peach james]

been done before. written up in MRC ~1986 or so, memory serves is in last MRC issue. That is with a gold cap, IIRC 1.2 farad, 6V. Problem with direction sorted via loco mounted chaneover switch. Since it doesn't eat .67v/per...the orignal uses a dpdt switch.

 

fitted to a HST & a diesel.

 

So, it is possible to do, but if it is worth it or not is another question.

 

James

[hollywoodfoundry]

Here's a 'fag packet' sketch of how you could probably connect a pancake motor across a capacitor as an 'electronic flywheel' (provided you could find a capacitor with a voltage rating and capacity compatible with your aims).

<SNIP>

 

I think the difficulty in attaching a flywheel to a pancake motor, as mentioned by puck, was more in the physical problem of doing so. There is no shaft to mount it on and very little room to do so.