# Hybrid Drive



## nesincg (Oct 13, 2008)

I didn't want this to get buried or hijack the MRC thread so I started a new one. 



so...

I have purchased a few of these cheap MRC AD322s. I want to install hybrid power. Anyone installed Hybrid drive using other than Lenz decoder? Possible?

For those who don't know, the idea is simple. Use track for power to the Locomotive, but when it gets to a dirty spot, it uses a battery backup on board. Once it gets back to clear track, it switches back and recharges the battery to boot. Never have to worry about stopping on a dirty spot and not getting going.


Good page (but I think old) regarding the topic:
http://www.tttrains.com/dcc/hybriddrive/index.htm




Thanks,
Chris


----------



## lkydvl (Jan 2, 2008)

why not just switch to battery power and forget all the wizardry?


----------



## lownote (Jan 3, 2008)

Dave Bodnar has done some experiments with using a large capacitor--really large--to smooth out variations in voltage. But the caps he used were so large they needed a trailing car. Do a search for "dave Bodnar" and click on "articles" and you'll find it. 

I keep hearing about new "supercaps" that are smaller and more powerful, but they haven't hit the market yet


----------



## rwbrashear (Jan 5, 2008)

Chris- 

Have you tried reading George Schreyer's website? He has a nice discussion regarding the use of capacitor power back-up for largescale decoders. 

http://www.girr.org/girr/tips/tips5/dcc_tips.html#dirt 

There is also a discussion about 'What DCC Outdoors Should Be.' 

Best regards, 
Bob


----------



## DKRickman (Mar 25, 2008)

I have some questions about this concept.

Referencing these sites:
http://www.girr.org/girr/tips/tips5/dcc_tips.html#dirt 

http://www.tttrains.com/dcc/hybriddrive/

Can a capacitor/battery be installed across the bridge rectifier of ANY decoder, and still allow it to function? Will that function include the "capacitance pickup", reading the DCC signal even through an insulator? Or is that feature only available on the Lenz Gold decoder?


Is the battery cutout necessary? The capacitor on the first page is shown installed without any sort of switch, whereas the batteries are shown switched through a relay. Is that simply to help with programming, or is there another benefit?

If I may speculate on my own questions, I'd guess that the results mentioned in the first page indicate that the decoder was still receiving a signal. I would expect the decoder to stop the motor as soon as it lost signal, even if there were still power available to it. I suppose the test would be to wire a larger battery in parallel with the BR output, and see what happens across a large insulated section of track, such as over a sheet of paper or painted rails. I would also guess that the battery cutout is not absolutely required, but makes operation, and particularly programming, easier.


I would like to hear what the experts have to say, but please, please, PLEASE, no bickering. I don't care who came up with the idea, I just want to know if it will work and how to implement it.


----------



## Trains West (Oct 4, 2008)

I thought others would post a reply but I will make a stab at it 

any decoder that you can get to the full wave bridge and will work with dc power will work ......

I just did a DH163 to try this out on a small speeder I have ........

you can use the blue wire for the positive but must add a negitive lead to the bridge on the decoder .....

the cap with the inflow resister and bypass dioide will be added to these leads ....

the basic idea is that if you loose contact with the rail and the dcc power the cap will discharge and the decoder will run on the DC power from the cap .....

during this time you will not control the loco as it has no DCC signal it will just run until the battery or cap is out of power or until it sees DCC power again .....

the drawback is that if the layout powers down the loco will take off at full power untill the cap has no more power ......

to control this on mine I am going to add a relay to F1 on the decoder and isolate the cap when parked .....


----------



## DKRickman (Mar 25, 2008)

Posted By Trains West on 10/13/2008 5:17 PM
the basic idea is that if you loose contact with the rail and the dcc power the cap will discharge and the decoder will run on the DC power from the cap .....

during this time you will not control the loco as it has no DCC signal it will just run until the battery or cap is out of power or until it sees DCC power again .....

the drawback is that if the layout powers down the loco will take off at full power untill the cap has no more power ......




Since you have this system up and running, perhaps you could answer some questions about it?

Will the loco run at full power whenever the DCC signal is lost, such as at power down, removal from the track, etc.?

If the loco is running at 1/2 throttle and encounters a loss of signal, at what speed does it continue to run?


Is there a lag between applying throttle and the locomotive moving?


As I understand it, this essentially functions like a constant DC voltage at the track, correct? If so, how do decoders which cannot operate on analog DC handle this modification?

Have you tried to get the "capacitance pickup" to work, running the loco onto a fully insulated section of track and attempting to control it? I understand that the Lenz Gold decoders can do this, but do any of the others? It seems as though they should, based on Mr. Ames description.


----------



## Trains West (Oct 4, 2008)

_Since you have this system up and running, perhaps you could answer some questions about it?_ 
the only thing I have running is a decoder on the bench that is why I was hopeing others would post......




_Will the loco run at full power whenever the DCC signal is lost, such as at power down, removal from the track, etc.?_ 
yes it goes to full power if you needed to you could put more dioides inline to drop the voltage out of the cap .......




_If the loco is running at 1/2 throttle and encounters a loss of signal, at what speed does it continue to run?

_full power




_Is there a lag between applying throttle and the locomotive moving?

_no the decoder sees full track power


_As I understand it, this essentially functions like a constant DC voltage at the track, correct? If so, how do decoders which cannot operate on analog DC handle this modification?_ 
yes you are right constant droping voltage ...... decoders without analog do not run on dc and the loco will stop moving ...... but what decoder does not work on analog?




_Have you tried to get the "capacitance pickup" to work, running the loco onto a fully insulated section of track and attempting to control it? I understand that the Lenz Gold decoders can do this, but do any of the others? It seems as though they should, based on Mr. Ames description.


_I do not even know what you are talking about here ........ I have run dcc locos into dc for years and never had it pick up the signal ....... the dcc info *is [/i]*the track power so if you do not have track power to run the loco then you bo not have the signal


----------



## Greg Elmassian (Jan 3, 2008)

This term "hybrid drive" has been used a lot by Stan Ames for Lenz. 

They use a capacitive pickup circuit to sense the transitions in the DCC signal. So, they are able to sense the signal under certain conditions where they cannot pick up power. This feature coupled with a battery or large cap allows the loco to run a certain amount on very dirty track. The claim is that this produces superior running on dirty track. I have heard that there are other byproducts of this design that can cause problems. The ability to pick up the DCC signal when you do not have a complete circuit means the decoder can also pick up noise and think it is dcc... so you can misinterpret noise as signal and do goofy stuff. 

It's something you should try and make your own judgement. It's not magic though. 

Regards, Greg


----------



## nesincg (Oct 13, 2008)

I think I'd rather go for a battery than a capacitor. The cap seams simple enough but I want my Loco to be powered for longer periods from a battery.

I want to be able to stop on a dead spot and then start again. If you look the first video here: http://www.tttrains.com/dcc/hybriddrive/example_video_clips.htm, you'll see that this loco receives signals without actually touching the track. An important line from the same website: 
=================
Capacitance pickup: A capacitor can be defined as two pieces of metal separated by an insulator. In model railroading the metal wheel on the locomotive and the metal track with dirt in-between form a natural capacitor. The DCC signal is a bi-polar signal meaning it has semi equal plus and negative segments for each bit. Combined this means that the natural capacitor between the locomotives wheels and the track will have a positive charge followed by a negative charge at the exact rate as the DCC signal. Translation the DCC signal can be received by the Decoder without direct contact to the rail so long as it is powered.
================= 

Sounds to me like it will get a signal, even on the dirty track. In fact, another point he makes is that it only has to be one of the tracks. So for wiring, I'm going to have to figure out this schematic so I can add to my AD322s. It includes an automatic switch that shuts off the battery when the DCC decoder has turned off or is in programming mode. Not sure how the last one works but I'm going to give it a shot.

Anyone else done this? Please?

Thanks,
Chris


----------



## DKRickman (Mar 25, 2008)

Chris, 

I saw that, too. I'm hoping someone here will be able to say definitely one way or the other, whether that is a Lenz-specific feature, or something that any decoder can do. I suppose it depends on just how good the decoder is at picking up faint signals, since I doubt they'd be anywhere near as strong as the full power DCC signal by the usual circuit.


----------



## Greg Elmassian (Jan 3, 2008)

The capacitive "signal input" seems to be pretty exclusive to lenz. Strength of signal is not as much a problem as being able to discriminate between noise and the desired signal. Again without impuning lenz, in the world you don't usually get something for nothing. There's a reason that not all decoder manufacturers pick up the signal the same way. 

Regards, greg


----------



## DKRickman (Mar 25, 2008)

It seems to me, then, that there are three distinct options for a useful system. 

1) Use regular DCC decoders, unmodified, and clean your track. The advantages are that you don't have to modify the decoder, can use any decoder you like, and get to keep the warranty. The disadvantage is a dependance on track power. 

2) Modify decoders as mentioned above, using a capacitor just large enough to get the engine over any spot of dirt without causing it to take off and run forever. The advantages are the ability to use any decoder and being able to operate over dirtier track. The disadvantages are voiding the warranty and sometimes losing control of the engines. 

3) Use the Lenz Gold decoders. The advantages are being able to buy a decoder off the shelf, keep the warranty, and use the fancy features even on really dirty track. The disadvantages are being limited to a single decoder and occasional odd behavior. 

Without having tried all three, or in fact any of the three, I'd guess that option 1 is the most practical when it comes down to it. Now, if the battery terminals and capacitance pickup became standard features on all, or at least most, decoders, that might be different.


----------



## StanleyAmes (Jan 3, 2008)

Posted By DKRickman on 10/13/2008 11:14 PM
It seems to me, then, that there are three distinct options for a useful system. 

1) Use regular DCC decoders, unmodified, and clean your track. The advantages are that you don't have to modify the decoder, can use any decoder you like, and get to keep the warranty. The disadvantage is a dependance on track power. 

2) Modify decoders as mentioned above, using a capacitor just large enough to get the engine over any spot of dirt without causing it to take off and run forever. The advantages are the ability to use any decoder and being able to operate over dirtier track. The disadvantages are voiding the warranty and sometimes losing control of the engines. 

3) Use the Lenz Gold decoders. The advantages are being able to buy a decoder off the shelf, keep the warranty, and use the fancy features even on really dirty track. The disadvantages are being limited to a single decoder and occasional odd behavior. 

Without having tried all three, or in fact any of the three, I'd guess that option 1 is the most practical when it comes down to it. Now, if the battery terminals and capacitance pickup became standard features on all, or at least most, decoders, that might be different.


Perhaps I can help you out with this. The easiest way to look at all this is the separate the concept of getting the signal to the module in the locomotive and getting the power to the module in the locomotive. Once you separate these two concepts you can understand just about any control system. 
On the power side you need to determine the amount of time you will depend on track power and the amount of time you want to depend on on-board power. For locomotives with good pickup or clean track the amount of on-board power needs are much less then you need if you have no track power at all. Some decoders are designed for Aux power but many are not and have no method for differentiating when the track signal is present or when it is absent. 
When you consider the signal reception you can get the signal from the track or from a radio receiver or any other method you desire. The concept behind Hybrid drive is to combine the various approaches in ways that can maximize the benefits of the various approaches. 
Simply adding aux power does not do much and can have interesting side effects unless you also address signal reception. For example you power the decoder from internal power and hook up an GWire receiver and have a total Battery/RC solution. 
Another approach is to use capacitance pickup in the decoder. Currently the Lenz decoder is the only one in the market but this may change in the next year. I have tested this method of pickup with packet testers and can get virtually 100% packet reception to the decoder in all track environments. I have no idea what Greg is talking about in regards to odd behavior and suspect its just another internet rumor. My experience is that most people believe they do not need capacitance pickup with on board aux power until they try it out. The improvements in performance quite dramatic.

Hope that helps.

Stan 
http://www.ttrains.com/largescale


----------



## Trains West (Oct 4, 2008)

thanks for the info guys ... I learned somthing new 


if you you are going to have batterys onboard then why not just go with airwire ?

it is still dcc

http://www.cvpusa.com/


----------



## DKRickman (Mar 25, 2008)

Mr. Ames, 

Thanks for the response. I was hoping you'd chime in, since the original article was yours. 

The concept is relatively simple, and I think is pretty well understood. The question seems to me to be one of practicality. Can this work with any decoder, or is it proprietary? Is it worth the effort and cost? 

On the first question, you and others have adequately answered the question. Lenz decoders are the only ones that work like this at the moment. Others can be modified, but will not recieve commands except on clean track. 

As for being worth it, I suspect that is a much more personal question. Being able to run over a piece of paper is cool, but I can't think of any time that I've actually wanted to. Being able to run on dirty track is handy, but the cost seems to be the need for separate power and sound decoders and a reserve power source. That means $150-$200 worth of stuff in a loco, plus the fun of wiring it and packaging it, compared to less than $150 for a good power & sound decoder and having to clean the track. For small locos, and especially in the smaller scales, the numbers become much less favorable, since one can get a decent power & sound decoder for around $50, and the packaging is much more convenient. 

My own opinion is that it's not worth the trouble at the moment, but that it's a really interesting idea, and one that I'd like to see become more readily available. I would love to hear from other people who have tried it and can comment from real world expereince, whether they feel it was worth the investment or not.


----------



## nesincg (Oct 13, 2008)

Well there is a good insight Stan, thank you. Still have 1 question. Is this capacitance pickup a possible decoder mod or more of a hardware function?



If not, this seems to be my 2 solutions for a 12 dollar decoder and hybrid drive:
1. Power the decoder from internal power and hook up a GWire receiver.
2. Upgrade to a Lenz decoder.



I've spent only 100 bucks on my whole used DCC system including 4 decoders. Buying all this stuff again is not currently in my budget. Buying some rechargeable batteries, a few relays, and resistors does fit my budget. Either way, I will likely attack this project just for the fun of it.



I myself think this hybrid drive is where we will all end up in a few years. I think the idea is great and technology is cheap now. I will likely buy new lenz decoders and do option 2 some time next year.


Any ongoing insight or suggestions are welcome.


Thanks,
Chris Nesin


----------



## Road Foreman (Jan 2, 2008)

Scott, 

Most decoders can have the analog ( DC ) power turned off.. Most of the HO clubs do this to stop run-a-way loco's.. You can do this to any loco that you will run on your layout only.. If you have a traveling loco you will want to leave the analog power on, so you can run on DC layouts.. 

BulletBob


----------



## steam5 (Jun 22, 2008)

I am currently trying to install a lenz gold decoder with the power module described on http://www.tttrains.com/dcc/hybriddrive/ 

My installation does not appear to be working. When does the relay energise? Eg when a DCC signal is detected?

Or do I need to change some CVs before it will work?

I tested the transistor and relay circuit with a power supply and the relay works.

Any help would be great, thanks.

PS I removed the switching circuit and directly connected the battery and it works, so it’s just the switching circuit that is the issue.


----------



## nesincg (Oct 13, 2008)

steam5

Please keep us informed on your fixes, workarounds, or other issues that arise during your installation. I'll be referencing them soon enough.

Thanks,

Chris


----------



## DKRickman (Mar 25, 2008)

Posted By nesincg on 10/15/2008 8:17 PM
steam5

Please keep us informed on your fixes, workarounds, or other issues that arise during your installation. I'll be referencing them soon enough.

Thanks,

Chris 




As will I. I'll be very curious to hear how the expereince turns out, and whether you feel it is worth the time and money, compared to either regular DCC or battery power.


----------



## steam5 (Jun 22, 2008)

Well as there is some interest to the project I’ll keep you posted up to the minute!

I lied a bit when I said worked before in my previous post.

My test is a couple of sheets of news paper on the track.
 
Last night when I hooked the battery up directly to the decoder it would have trouble driving on the paper, but would go with some help of the 0-5-0 shunted. But when I changed direction on the hand controller much to my surprise the head light came on! I turned it up and push the loco off the paper. I assumed it was the battery not having enough change on it. So I left it on the track for about 10 minutes, but no improvement.

When I go home from work tonight I placed the battery pack directly on the power supply to give her a boost. After tea I plugged it directly in again (no switching circuit) and it worked! Drove right onto the news paper and off again!

Now all I have to do is get the switch circuit working, and check if the decoder is charging the batteries at all. My guess is it is charging but very slowly! This will be fine for this application. I will work this out with the multimeter latter on.

I will let you know when I get the switching circuit working, and then workout id there is anyway to fine tune the circuit. Then have a good hard think about if this feasibility study should be put into full production!


----------



## Trains West (Oct 4, 2008)

all batterys develop memory even when they say they do not .......

so with constant charging from the track and only a discharge here and there how well do you think the batterys will hold up without having to fuss with them ?

also without a charging circut do you not think the batterys will overcharge ?


----------



## StanleyAmes (Jan 3, 2008)

Perhaps I can help out with some of the confusion.

When you use the supercaps built up as a product all the electronics are built in so all you have to do is connect three wires to screw terminals on the decoder. When you build your own circuit it takes a little more work.

Switch

The switch’s only purpose is to turn off the on-board power source when there is no longer a need for it to power the locomotive. On some of my locomotives I use batteries as the principle power source for the locomotive and the switch is a DPDT. In one switch position, the battery is connected to the charge socket and in the other position the battery is connected to locomotive.

Using a manual switch is real simple but has the downside that you have to remember to turn off the power after an operating session to prevent the batteries from continuing to discharge.

An alternative option is to use an electronic switch (such as a relay or direct electronics) to turn on and off the internal power. The way it works is that when the decoder sees a signal the decoder activates the switch by bringing a pin to ground. The downside of an electronic switch is that the decoder must get enough track power through the pickups to turn on the switch. In real practice on real track (rather than on paper) this is not a real problem.

The advantage of a relay as the switch is that it is simple and readability available. The downsides is that on the Lenz decoder the activation switch can not sync a lot of power so you need to activate the relay using a PnP transistor and you need to calculate the dropping resistor to the relay so that the chosen range of track voltages is sufficient to activate the relay. If you can not activate the relay your resistor is likely to large. A good way to test this is to hook up the transistor to a decoder function output. When the function is on the relay should be activated. By changing the DCC track voltage you can select a resistor that works in a wide range of track voltages.

Charging Circuit

Battery chemistry varies between the different battery types. I tend to like the normal NiMH batteries for this application. You can trickle charge these batteries at a 3% rate with no damage to the battery. I use a very simple resistor and diode for my charging circuit. When charging the resistor limits the current to the batteries. When discharging the battery current goes through the resistor. To calculate the resistor value use V=IR or R=V/I where V is the difference between the DCC track voltage (-1 volt for the decoder rectifier) and the max voltage from the battery pack (typically 1.5 volts per cell). I use 1 100ohm resistor for 900ma batteries and this works rather well.

Note that this charge circuit does not charge the batteries quickly. In actual use on dirty brass or Aluminum track the internal power is only needed for frequent but short sections.
You can see the effect using a normal light bulb connected to the track pickups. When the light is flickering or off the internal power is in use. If the light is on solid the internal power is not being used.

Naturally a more sophisticated charging circuit that uses voltage regulation can charge the batteries more quickly and will work with fewer cells and over a greater range of track voltages but again it is a tradeoff and I tend to go towards simplicity.

Hope that helps.

Stan 
http://www.tttrains.com/dcc/hybriddrive/index.htm


----------



## steam5 (Jun 22, 2008)

Stan, thanks for the extra information.

The reason for my switching circuit not working was the voltage to the relay was not sufficient. I was using a 15V supply; I removed the dropping resistor which I had calculated. When I up the supply voltage I will add the resistor back again.

With the switching circuit working now I hooked it all up and it worked! It really wowed me out to see the loco drive onto a sheet of newspaper and reverse back off it!

I installed my first sound decoder after this success and once it was all complete the hybrid drive continued to work.

The next morning I tried it again and it had some trouble on the news paper, the relay click out shutting down the loco. I could see no reason for this, but my only guess is the battery was flat. I found I had an 18V supply and I hooked that up to the DCC system and left the loco on the track to charge up. After a bit of charge time it worked. I assume this was the reason, I did not have enough time to go back and verify the results, and perhaps it was a fluke?

Stan I had thought of researching some fancy charging circuit, but I agree with you, just keep it simple!

Assuming it does work properly with the larger supply and I have successfully installed a Lenz gold decoder with a hybrid drive and I am very happy with the results. Unfortunately I do not have an outdoors layout, so I can not give it any real world tests.

I believe cheaper G scale decoders are on the market, but I use only lenz in HO and I have always been very impressed by them, especially their motor control. Now that I’m beginning to dabble in G using the gold maxi was a no brainer for me.

Installing the hybrid drive did cost me more on top of an already not cheap decoder. This installation was a feasibility study for me as you know; I also installed a phoenix P5, so considering the cost of the overall installation the few components for the hybrid drive was not all that much.

I have proved the concept works, but not tested it in real world scenarios. Would I install it again? Sure I will, now that I have nutted out the circuit and how it operates future installations will be much easier. I think bumping up the voltage will help things to, but my Lenz set 100 can only take 18V max, plenty for my HO! But I will get a Lenz booster soon which has a higher voltage capability.

Give it a go guys! Let me know how it goes in the garden!


----------

