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Lais Decoder - Functionality with Hornby Select


sirandy
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Hi All,

 

I am new to this forum, and hope to gain some valuable info, and maybe be able to contribute too!

 

Ok, I have a small DCC setup, with Hornby componenents. I have one loco as aprt of the set that is DCC compatible out the box, and I have a few older loco's that have been tested and are functional in a DC environment. I have converted the Ringfield motors to CD Can motors with 3D printed adaptors. As expected, the loco's run way to fast as the motors are 6V and are this not well equiped to run and last in a DC environment (especially as the user is my son who is 6) he will destroy them by trying to run at top speed. I am going to DCC them, and am looking at the cheapest option as a startpoint, until I gain more experience in installing and setting up.

For now, I have a Hornby Select controller that has been upgraded to the lastest FW which includes the ability to adjust CV values (or some at least). I need the very basics out of this for now, and this will include being able to limit voltage to the motors, by programming CV29 (I believe) and I will set accel and decel rates.....thats it, No lights, sound or anything else.

 

What I need to know, if people have had experience with this, is whether the Laisdcc 860021 motor + 4Function DCC Decoder can be programmed from the upgraded Select controller, first and foremost to adjust the start, mid and top voltage throughput. If not perhaps someone can advise on a budget decoder where this is possible.

 

I really do appreciate the feedback.

 

Regards, Andy

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Cv29 does not alter the voltage that is output by the decoder. Some decoders, e.g. Zimo do allow you to set the maximum voltage using CV57 but I don’t know if LAIS support this.

 

A Zimo MX617 has an average current rating of 0.8A with a peak of 1.5A and will provide much better control than a LAIS decoder - it is only £20 plus postage.

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Thanks for the response, I stand corrected, I believe the correct CV numbers are CV5-Vhigh and CV6 - Vmid, adjusting these will be the way to limit top and mid voltage.

 

I will look into whether they can be programmed or not. Will also look into the Zimo units. Laisdcc say on their site the 860021 has a 2A peak and 1A nominal, and considering I wont be using any functions, this may be able to handle high amps.

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I only use Laisdcc decoders, and yes, you can change the cv to limit a loco's top end, (if using a CD motor like Strathpeffer Junction offer, it's advisable) I can't remember the cv, but Google: Laisdcc Manual and everything you need is included in the document. Laisdcc decoders are NMRA standard so it should work with a Hornby controller

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Reducing or altering CV5 doesn't reduce the actual voltage that is applied to the motor, what it does is affect the duty cycle of the pulse signal this reducing the average or apparent voltage to the motor. If the track voltage is 15v at CV5=252 then the peaks will still be 15v (less decoder internal losses) however if you reduce CV5 to 126 then because you have reduced the duty cycle by 50% then the average voltage will be ~7-8v.

 

CV57 on Zimo decoders reduces the actual voltage that the decoder outputs in 1/10 of a volt. If you want a max 6v you would set CV57=60 and the max voltage would be 6v. If you leave it at CV57=0 then it will output whatever is put in, meaning if your track voltage is 15v then you will get out 15v (less decoder internal losses)

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We are going off question here, and making a simple question difficult.

So, simple question, simple answer,

Yes, the decoder you have can be programmed to do what you want using a Hornby select. just follow the downloadable manual.

https://laisdcc.com/manual/

Page 9.

 

Interesting explanation from WIMorrison, but that's Zimo decoders, this is a direct quote from the Laisdcc Decoder Manual.

 

CV5. This area controls the locomotives TOP volts. Its total range is 0~255 and its default is zero (in this case zero and 255 have the same meaning - not limited). As with CV2 each of the 255 steps is equal to about 1/20th of a volt. As we have 128 speed steps available at our controllers I like to vary this in even numbers. For this “first step in programming", let’s just say our loco runs far faster than it should and set it to 180.

Edited by Smudge617
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Really appreciate all the feedback, I am slowly starting to learn this stuff. 

I managed to get the decoder connected up, and I have activity. As expected, the top speed was 'warp' speed, so I needed to dial that down....

I started by using CV5 and set that at 64 (I assumed that if its a total of 128 steps, 64 would be half) and set CV6 at 32 (assumed to be half of the 64 I set in CV5). Its working but the loco moves off OK, but then gets to about 1/3 throttle, and starts to back off on the speed, and you have to move it past halfway to get it to get up to speed again.

 I think I am getting slightly mixed up between the 0-255 steps of the decoder and apparently 128 steps of the controller...getting confuzzed now. Obviously I cannot 'read' the values of the CV's with the Select, so I am now not sure how to get the positions I want.

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1 hour ago, Smudge617 said:

We are going off question here, and making a simple question difficult.

So, simple question, simple answer,

Yes, the decoder you have can be programmed to do what you want using a Hornby select. just follow the downloadable manual.

https://laisdcc.com/manual/

Page 9.

 

Interesting explanation from WIMorrison, but that's Zimo decoders, this is a direct quote from the Laisdcc Decoder Manual.

 

CV5. This area controls the locomotives TOP volts. Its total range is 0~255 and its default is zero (in this case zero and 255 have the same meaning - not limited). As with CV2 each of the 255 steps is equal to about 1/20th of a volt. As we have 128 speed steps available at our controllers I like to vary this in even numbers. For this “first step in programming", let’s just say our loco runs far faster than it should and set it to 180.


I’m afraid you are wrong. CV5 does not control the top volts, it controls the duty cycle proving an apparently lower voltage but the top volts remains the same.

 

 

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I'm not arguing with WIMorrison, I can only go on what the manual says.

 

I don't have a Hornby select, that's one of the reasons why, I can't check that I've written the right value to the right CV.

 

You can reset the decoder (write 4 to CV8)  or (4 to CV30) so it returns to factory defaults and start again or can I suggest you try this, its a 3 point (speed) curve I use for my Eurostar.

CV3 = 12, CV4 = 12, CV5 = 220, CV6 = 96

If you feel it's still too quick, decrease all the values by 2 or more till your happy.

Edited by Smudge617
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Thanks all, I am still confused a bit but  I am going to try and slowly get it sorted. I have reset CV2 to 0, CV3 & 4 are the accel/decel rates so will leave those for now.

Will set CV5 at 150 and CV6 at 75 and see if that helps. The loco I am running is a Hornby 8F with tender drive that I have converted to a CD Can motor and being 6V its lightning fast. I am assuming that if the actual voltage doesn't change, I at least need to get the speed to half, as a start point, will see how that goes.

 

I looked at the Lais CV list and CV57 is "Dither Amplitude" and is set at 10, so its probably not the same functionality as the Zimo decoders, so I will leave that as is for now.

 

Great help, thanks lads.

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Yeah, so the word on Laisdcc being rubbish, seems to ring true... one decoder has died, while on the track...was going well, was finally at a speed that was close to what I wanted and then on a circuit, it just started slowing down to a crawl, kept getting slower and slower, zero response to throttle inputs....stopped dead. I tried resetting the decoder, tried renaming it and it was taking the inputs from the select....and then....nothing.

 

So, since I had two, I decided to wire it up to a 0-4-0 loco, probably one of the simplest to hardwire....zilch, dead, wont even accept a write from the controller. 

 

Rubbish I suppose....

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I have 27 Loco's, 18 with Laisdcc, so far, in 2 years I've blown one, and that was me causing a short circuit. and one was faulty which was replaced.  So I have to disagree with you. There are two main suppliers (assuming you bought it on eBay) contact them, you can send them back, as they do have a guarantee. If you've bought it from BLT Technical services, Brian will go out of his way to solve the problem.

But sounds more like the motor caused the burn out, and overloaded the decoder, if the motors dead second one wont work.

I'm assuming when you removed the decoder the 0-4-0 ran on DC ?

Edited by Smudge617
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Smudge, one went into a Class 8F that had the ringfield conversion to cd-can, the other went into the DC based 0-4-0. The cd-can conversion went well for a while and was working fine after I had made the adjustments to the CV's. I left it overnight, on the track, switched off at the mains. The next morning, I switched on the track, and was using a dcc flying scotsman that had a derailment and short circuited. Do you think its possible a short from another train would make another decoder fail? I would expect the Scotsman or the other 0-6-0  that was also on the track to also fail, but they are running fine.

 

The 0-4-0 went from its packet, got hard wired, straight to the track and was dead as a dodo from the get go.

 

I bought them from Digitrains, so I will send them both back and see if there is anything that can be done to test them.

On the 8F, I dont really like how the tender drive gets its power through that single drawbar pin, the chassis frame of the tender is VERY close to that pin and when putting the train on the track, its easy to short circuit. Is it possible that a short circuit like that would blow the decoder, and if so, I would have thought it would blow straight away. This train was running fine until it just started to act erratically and came to a stop....done.

 

I am hunting a different controller now, as being able to read as well as write cv's would be most useful. I may get a SPROG and use that to program the decoders and then give the pre-programmed loco's to my son to play with.  I was hoping to get everything done by the time he gets back from half-term...

I prefer the select for him as it is very simple for a 6 year old to operate.

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Iain (Morrison) is correct

If you really want to reduce the maximum voltage for a lower voltage CD motor (IIRC some are only 3v!) you should reduce the actual voltage from the decoder and only decoders such as the Zimo with a voltage adjustment will do it.

CV 5 does not adjust the voltage it adjusts the speed and if Lais claim it does they are wrong.

 

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AFAIK all decoders use PWM to adjust the output, this changes the average voltage seen by the motor and consequently its speed. Its the inductance of the motor windings that prevent the motor seeing the peak voltage when the duty cycle of the PWM is reduced.

What to you think that ZImo does differently?

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Zimo enables the decoder to limit the absolute maximum voltage to the motor, not the apparent maximum voltage. 
 

The method used on other decoders (and the default setting for Zimo) will output the peak voltage to a motor at all times. This means that if the peak voltage is 15v then the motor is always receiving 15v pulses and it is the number of pulses that provides the apparent voltage - very few pulses means a low apparent voltage, a large number means a higher apparent voltage - but the peaks are still the same.

 

By changing CV57 on a Zimo decoder to 60 then the peak voltage will always be 6v. Fewer pulses will mean a lower apparent voltage but the pulses will never be more than 6v.

 

A motor rated as 12v will generally not suffer damage from a 15v pulse, but a motor rated at 6v will not be happy with a 15v pulse. Many coreless motors that run poorly on decoders can be made to run very happily using a. Zimo decoder and limiting the peak voltage using CV57.

 

Another benenefit of using CV57 to set the maximum voltage and hence the top speed for the motor is that the top speed will be set at 252 speed steps within the decoder leaving the full range to control the speed. If you use the suggested method of reducing CV5 to reduce the apparent voltage could mean with a 6v motor that CV5 is set to 100, and if CV2 is set to 20 as the start voltage then the effective control range is on 80 speed steps, whereas with the CV57 method there would be 232 speed steps - and a motor that will not burn out ;)

 

 

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1 hour ago, WIMorrison said:

 

The method used on other decoders (and the default setting for Zimo) will output the peak voltage to a motor at all times. This means that if the peak voltage is 15v then the motor is always receiving 15v pulses and it is the number of pulses that provides the apparent voltage - very few pulses means a low apparent voltage, a large number means a higher apparent voltage - but the peaks are still the same.

 

Iain, Is that correct?:scratchhead:

I thought the pulse rate was constant (depending on decoder settings) and only the mark/space ratio is changed when you change speed.

It is the duty cycle that determines the average voltage to the motor.

 

23 hours ago, Grovenor said:

AFAIK all decoders use PWM to adjust the output, this changes the average voltage seen by the motor and consequently its speed. Its the inductance of the motor windings that prevent the motor seeing the peak voltage when the duty cycle of the PWM is reduced.

What to you think that ZImo does differently?

AFAIK the Zimo has a way of reducing the actual value of PWM voltage, rather than just using the average.

 

The reference voltage for motor regulation
CV # 57 specifies the base voltage used for motor regulation. For example: if 14V is selected (CV value: 140) the decoder tries to send the exact fraction of this voltage, determined by the speed regu-lator position, to the motor regardless of the voltage level at the track. As a result the speed remains constant even if the track voltage fluctuates, provided the track voltage (more precisely, the rectified and processed voltage inside the decoder, which is about 2V lower) doesn’t fall below the absolute reference voltage.
 The default value “0” in CV #57 selects the “relative reference”, which automatically adjusts the refer-ence voltage to the available track voltage. This setting is only useful if the system can keep the track voltage constant at all times (stabilized track output) and the resistance along the track kept to a mini-mum. All ZIMO systems keep the track voltage stable even older systems, but not every system from other manufacturers do, especially the relatively cheap systems built before 2005. It is not recommend-ed to set CV #57 to “0” with systems that don’t keep track voltage stabilized. Instead set this CV about 2V below track voltage (i.e. 140 for 16V).
 CV #57 can also be used as an alternative to CV #5 (top speed), which has the advantage that the full resolution of the 255 speed steps remains available. CV Designation Range Default Description
#57
Voltage reference
0 - 255
0
Absolute voltage in tenth of a volt applied to the motor at full speed (max. throttle setting).
Example: A system without stabilized track voltage is set to 22V at idle but drops to 16V under load: A good
setting would be CV #57 = 140…150.
CV #57 = 0: automatically adjusts to the track voltage (relative reference); only useful with stabilized track voltage.

 

Depending on PWM frequency the inductance will have more or less effect on the rise of the voltage.

 

 

Getting a bit technical for newcomers!

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39 minutes ago, melmerby said:

Iain, Is that correct?:scratchhead:

I thought the pulse rate was constant (depending on decoder settings) and only the mark/space ratio is changed when you change speed.

It is the duty cycle that determines the average voltage to the motor.

 

...

 

Keith,

 

You are correct that it is the duty cycle that determines the apparent voltage, however I was trying to avoid overcomplicating a concept that isn't easy to grasp, however I will hopefully clarify here using this image.

 

spacer.png

 

The point I made remains the exactly same though, if the peak voltage output is 15v with from a decoder then it is always 15v that the motor receives, just for a varying period of time - the pulses I referred to earlier - unless you use the Zimo CV57 feature to reduce that voltage, which is what Zimo recommends be done.

 

The comments about the number of speed steps available for control of the motor also remains valid.

 

Hopefully nice and clear now :)

 

 

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I answered the OP to the best of my knowledge, I'm not an expert on such things I rarely change any CV on my decoders, so I could only go so far as to how much I actually knew but this forum is for anyone who is in need of  help and I have received that help from members across the world to better enjoy their modelling  I believe my suggestion was valid, it will do what the originator would like, but not through reducing the voltage to the motor, and I was corrected by another member, but he didn't say which CV would need to be changed on a Laisdcc decoder and used his experience and knowledge to say that on a Zimo decoder, which he is obviously more familiar with, which CV value controlled the Voltage.

 

After that comment, this thread went to hell. All the comments are very interesting, and all irrelevant to the OP. He has a 6 year old son, who likes to run his train set at full speed and Dad, as he's the one who will have to buy a replacement, would like the train to go round the track without flying off and smashing against the nearest wall or floor. So can anyone, suggest which CV needs to be altered on a Laisdcc decoder so the Loco will run at a more sedate speed regardless of his 6 year olds throttle control. Any ideas ??

 

As an aside, I am aware what most of the more experienced members think about Laisdcc decoders, but, as an entry level decoder, it works, and is probably the most inexpensive "how to" decoder to learn from, I wonder how many of you when you first started in DCC put a expensive decoder in and blew it, because you didn't know what you were doing, anyone??? I would much rather fry a Laisdcc than a ESU. Personally I like them, to the extent I now have 27 loco's fitted with Laisdcc.

 

Edited by Smudge617
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21 minutes ago, Smudge617 said:

So can any one of you wizards of (Zimo) DCC decoders, suggest which CV needs to be altered on a Laisdcc decoder so the Loco will run at a more sedate speed regardless of his 6 year olds throttle control. Any ideas ??

 

The original post does ask for advice on a budget decoder, if the Laisdcc decoder is not suitable for controlling a 6 volt motor - hence the suggestion of Zimo as a better budget alternative.

 

On 18/10/2021 at 12:01, sirandy said:

What I need to know, if people have had experience with this, is whether the Laisdcc 860021 motor + 4Function DCC Decoder can be programmed from the upgraded Select controller, first and foremost to adjust the start, mid and top voltage throughput. If not perhaps someone can advise on a budget decoder where this is possible.

 

The issue is that there are two ways to reduce the apparent voltage that the motor 'sees'.  The first is to adjust the duty cycle using CV5 (which is, as I understand it all you can do with the laisdcc decoder) such that it only gets a pulse of power for a maximum of say 50% of the time depending on the value of CV5.  That is fine for a typical 12 volt motor as is fitted to most ready to run models, so if you find laisdcc decoders do what you need on new ready to run models, that is great.  However, as I understand it, it is not ideal to be powering a 6 volt motor with pulses of power that are more than twice the motor's rated voltage.  That is more likely to cause the CD motor that has been fitted to burn out.  The best way to ensure longevity of the 6 volt motor is to reduce the amplitude of the signal to the motor, so that it gets pulses of 6 volts rather than pulses of say 14 volts (or whatever the DCC booster puts out).  As I understand it, the laisdcc decoder does not have that functionality, hence the recommendation to spend a few pounds extra on a better budget decoder for locomotives fitted with 6 volt motors.

 

As I understand it, the advantage of lowering the actual voltage to the motor is that it leaves more of the duty cycle to provide finer control of the locomotive.  It therefore increases the longevity of the motor, reduces the maximum speed and provides smoother control.  I don't think the laisdcc decoder can do that - changing CV5 to give the desired top speed and hoping that the motor doesn't burn out too quickly is the only choice.

 

I don't have any laisdcc decoders or Zimo for that matter - just ESU.

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3 hours ago, Smudge617 said:

 

As an aside, I am aware what most of the more experienced members think about Laisdcc decoders, but, as an entry level decoder, it works, and is probably the most inexpensive "how to" decoder to learn from, I wonder how many of you when you first started in DCC put a expensive decoder in and blew it, because you didn't know what you were doing, anyone??? I would much rather fry a Laisdcc than a ESU. Personally I like them, to the extent I now have 27 loco's fitted with Laisdcc.

 

I started with 3 budget Lenz decoders (LE1000?) . I knew nothing about DCC but I didn't blow them because you couldn't, they were self protected.

(I've still got them but not in use as their loco control is poor by today's standards.)

Whether the Lais is as forgiving I don't know.

 

I won't buy Lais, mainly because of their performance but won't forgive them for starting their DCC range by blatant pirating of TCS decoders, which landed them in trouble.

It wouldn't surprise me if their current range includes functions back engineered from proper decoder designers.

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51 minutes ago, melmerby said:

I won't buy Lais, mainly because of their performance but won't forgive them for starting their DCC range by blatant pirating of TCS decoders, which landed them in trouble.

It wouldn't surprise me if their current range includes functions back engineered from proper decoder designers.

 

Wholeheartedly agree with this. Tainted product from the start. I wouldn't offer to work on a loco fitted with Lais decoders apart from removing it for something more legitimate. 

 

When I started out with DCC I went against a lot of advice on RMweb (or was it the BRM forum way back when???) and bought 10 Hornby R8215s, guess what, they reset to address 3 when there was a track short, blew or just randomly stopped working. So maybe the OP can learn from those of us who have tried and failed and invest in better quality decoders as the overall experience (and support from the comminity) will be better.

 

Zimo MX600R is a no brainer at the moment as has been said.

Edited by RedgateModels
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On 26/10/2021 at 13:04, RedgateModels said:

 

 

When I started out with DCC I went against a lot of advice on RMweb (or was it the BRM forum way back when???) and bought 10 Hornby R8215s, guess what, they reset to address 3 when there was a track short, blew or just randomly stopped working. So maybe the OP can learn from those of us who have tried and failed and invest in better quality decoders as the overall experience (and support from the comminity) will be better.

 

Even Hornby recognised the R8215 was a "Bad 'un" and would replace them with the upgraded R8249 if asked.

I had two in DCC fitted locos bought at different times from Ian Allan when in Stephenson Street.

They wouldn't work at all with my Lenz system.

The shop tried the first one on their test track (Basic Baccy DCC controller) and also drew a blank so gave me an R8249 as replacement.

For the other I went straight to Hornby, who asked what colour spot was in the microcontroller chip and once had determined it was one of the bad ones sent me two R8249 as recompense.

 

Both R8215 & R 8249 look identical, so It must just be rubbish firmware blown into the chip.

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One of the problems was Hornby fitted the dire R8215 into factory DCC-fitted locos (R____X) and these were still being found in shops for donkeys years after the NMRA warranted R8249 was introduced.

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