Z21 + DR4088LN-CS Detectors + Traincontroller

[melmerby]

I've just gone back to Coastal DCC and ordered some there for £65.95 each

Digikeijs are now €79.95, that's about £70 at current rates of exchange, so no cheaper.

[melmerby]

I have finally totally removed 15 x RS-8s, 1 x RS-16 & the Lenz system from the layout

I now have just Z21, DB-4 (booster) 7x DR4088 LN CS +  2 x DR4088 S88 CS + 1x DR4088 S88 Opto (replaces RS-16)

 

The biggest problem was that all the RS-8s were connected to the track blocks with both J&K wires which were twisted together.

The DR4088s do not like that at all and give false positives with anything more than a short length of twisted cable.

 

After doing the first one and got five false detections from 16, I went through the layout converting it all to single wire feed for the blocks with all the common wires commoned locally to the main track bus common.

Once I had done that and confirmed it was still working properly, swapping out the RS-8s was straightforward with no more false detections.

I am now redoing the first one and the false detections are going as I remove all traces of twisted cable.

 

I now have loads of DCC kit to sell on ‼️

 

 

Edited June 3, 2022 by melmerby

[RFS]

10 hours ago, melmerby said:

I have finally totally removed 15 x RS-8s, 1 x RS-16 & the Lenz system from the layout

I now have just Z21, DB-4 (booster) 7x DR4088 LN CS +  2 x DR4088 S88 CS + 1x DR4088 S88 Opto (replaces RS-16)

 

The biggest problem was that all the RS-8s were connected to the track blocks with both J&K wires which were twisted together.

The DR4088s do not like that at all and give false positives with anything more than a short length of twisted cable.

 

After doing the first one and got five false detections from 16, I went through the layout converting it all to single wire feed for the blocks with all the common wires commoned locally to the main track bus common.

Once I had done that and confirmed it was still working properly, swapping out the RS-8s was straightforward with no more false detections.

I am now redoing the first one and the false detections are going as I remove all traces of twisted cable.

 

I now have loads of DCC kit to sell on ‼️

 

 

 

Bet you're glad that's done! I certainly was after all that time under the baseboard ....

 

I sold on my kit relatively easily on Ebay. I put up the RS8s at £25 fixed price for the 2.2 versions, and £30 for the 3.2 versions and sold them all in about 2-3 weeks. I also sold the LZV100 set for about £150.

 

The DR4088s do seem more sensitive than the RS8s and I still see occasional false positives. For example, I have one schedule running through 3 blocks - A -> B -> C. A is the main station, and I notice sometimes that when the train enters C, block A turns occupied again even though the rear of the train is a good 2m away by that time. Cannot see what causes that and it only happens now and then. A and C are on different DR4088s which are also on different boosters.

 

I also have resistor wheelsets on the rear two axles of every train in order to provide protection against coupling failures. But I have noticed that sometimes these appeared not to be working, On one train I took the rear coach off to redo the wheelsets, and was surprised that the train was still sometimes behaving as though the resistors were still there. None of the remaining coaches had resistors or pickups. I eventually concluded that the problem was occurring when a metal wheel touches both rails as it passes over an IRJ. Tried it manually with a single wagon and when this happens, both blocks flag occupied immediately. 

 

Having resistor wheelsets on the last vehicle of every train eliminates this problem and I've now checked and corrected them where necessary. 

[melmerby]

THe bigest fag was untwisting all the wires to the blocks, once that was done fitting the DR4088s was relatively easy, it's taken about 3 weeks.

I've still got 3 blocks where there are permanent occupancy shown but I have cured that by using a capacitor between each of the terminals and the common +ve.

I reckon the inputs of the DR4088s are too sensitive to the electrical rubbish generated when you connect what is effectively a square wave across an undefined load.

A cap removes the high frequencies.

 

All my vehicles have resistors, not just the rear one, so no problems there.

[WIMorrison]

Keith

 

Did you use the 47uF capacitor value that I suggested?

 

interestingly whilst you say that the 1mA sensitivity is too low (though there are simple ways to reduce this sensitivity as I explained) most people I meet want to get their other detectors down to the same 1mA that the 4088 provides.

 

I know of another detector that will provide <3mA sensitivity on a Railcom detector however the supplier can’t get it, or the other devices, to the market due to component shortages - however it will come and they will be a real competitor to the current Digikeijs offerings.

[melmerby]

4 hours ago, WIMorrison said:

Keith

 

Did you use the 47uF capacitor value that I suggested?

 

interestingly whilst you say that the 1mA sensitivity is too low (though there are simple ways to reduce this sensitivity as I explained) most people I meet want to get their other detectors down to the same 1mA that the 4088 provides.

 

I know of another detector that will provide <3mA sensitivity on a Railcom detector however the supplier can’t get it, or the other devices, to the market due to component shortages - however it will come and they will be a real competitor to the current Digikeijs offerings.

Hi Iain

Yes I have put caps (I think you mean nF not  μF) on the affected ones, I'm down to three out of 100+ blocks that have needed that and I might be able to get one less with a bit of re-routing

 

I don't think it's the sensitivity per se as the RS-8s are about the same.

I have 12kΩ resistive axles on all vehicles and one vehicle is sufficient to show occupancy with either occupancy detector*, however RS-8s do not show occupancy with twisted wire feeds to blocks, DR4088s do if they are more than a metre or so, some feeds were quite long (> 2m)

I can only assume the DR4088s are picking up higher frequency rubbish and passing that through as occupancy, hence shunting the circuit with a cap removing it.

 

*I originally tested an RS-8 with approx 14v DCC signal and found that 14kΩ would show occupancy but it was near the limit, so I opted for 12kΩ for reliable triggering.

 

 

 

Edited June 4, 2022 by melmerby

[Andymsa]

52 minutes ago, melmerby said:

Hi Iain

Yes I have put caps (I think you mean nF not  μF) on the affected ones, I'm down to three out of 100+ blocks that have needed that and I might be able to get one less with a bit of re-routing

 

I don't think it's the sensitivity per se as the RS-8s are about the same.

I have 12kΩ resistive axles on all vehicles and one vehicle is sufficient to show occupancy with either occupancy detector*, however RS-8s do not show occupancy with twisted wire feeds to blocks, DR4088s do if they are more than a metre or so, some feeds were quite long (> 2m)

I can only assume the DR4088s are picking up higher frequency rubbish and passing that through as occupancy, hence shunting the circuit with a cap removing it.

 

*I originally tested an RS-8 with approx 14v DCC signal and found that 14kΩ would show occupancy but it was near the limit, so I opted for 12kΩ for reliable triggering.

 

 

 

This is something I have promoted for sometime not twisting the feeds from the detectors to the track. By twisting your increasing capacitance of the circuit and it appears some detectors are more vulnerable to this capacitance than others.

[melmerby]

58 minutes ago, Andymsa said:

This is something I have promoted for sometime not twisting the feeds from the detectors to the track. By twisting your increasing capacitance of the circuit and it appears some detectors are more vulnerable to this capacitance than others.

The RS-8 by the way it is laid out encourages feeding two wires to each block and once you have done that, twisting seems natural and it's tolerant of it.

 

I only ever had one block that showed false occupancy and that was using LDT auto reversers and I fed the wires half way around the layout, probably 8m or so, done that way as there is a lifting bridge in the middle of the double track reversing loop.

I ended up changing the blocks around so I could get one reverser to the other side and only a couple of metres from the blocks.

 

Unfortunately my former neat looking feeds to blocks now look like knitting gone wrong, but it works.

Edited June 4, 2022 by melmerby

[Andymsa]

2 hours ago, melmerby said:

The RS-8 by the way it is laid out encourages feeding two wires to each block and once you have done that, twisting seems natural and it's tolerant of it.

 

I only ever had one block that showed false occupancy and that was using LDT auto reversers and I fed the wires half way around the layout, probably 8m or so, done that way as there is a lifting bridge in the middle of the double track reversing loop.

I ended up changing the blocks around so I could get one reverser to the other side and only a couple of metres from the blocks.

 

Unfortunately my former neat looking feeds to blocks now look like knitting gone wrong, but it works.

 

Not a twisted wire in sight

 

all wires are lightly tied together to the boards, as they run around the layout they just lay in cable trunking 

 

 

[WIMorrison]

@melmerby I did mean 47nF - sorry 😆

 

I am just thinking out loud about the advice to place the capacitor (or resistor) between the C terminal and the feedback on the DR4088xx, but those terminals are effectively the left and right rails in the feedback. I am wondering if to simplify wiring the capacitor or shunt resistor could simply be place over the rails because in a simple circuit like we are describing it shouldn't matter if the component is at the start or the end of the wire - or am I barking mad?

Edited June 4, 2022 by WIMorrison

[melmerby]

4 hours ago, WIMorrison said:

@melmerby I did mean 47nF - sorry 😆

 

I am just thinking out loud about the advice to place the capacitor (or resistor) between the C terminal and the feedback on the DR4088xx, but those terminals are effectively the left and right rails in the feedback. I am wondering if to simplify wiring the capacitor or shunt resistor could simply be place over the rails because in a simple circuit like we are describing it shouldn't matter if the component is at the start or the end of the wire - or am I barking mad?

No Iain, they aren't

If you consider one side of the DCC system as high and the other low:

The high goes to the C terminal and some diodes are in series from there to the detection terminals which then go to the high rails of the various blocks, (the voltage developed across those diodes, when current is being drawn, provide the signal for occupied)

The capacitors go across those diode voltage droppers, (effectively they are a low pass filter)

 

The low DCC terminal goes to the low rail

 

Edited June 4, 2022 by melmerby

[melmerby]

4 hours ago, Andymsa said:

 

Not a twisted wire in sight

 

all wires are lightly tied together to the boards, as they run around the layout they just lay in cable trunking 

 

 

Now try replacing 2 x 8 input block detectors neatly wired up, a metre or more apart with 1 x 16 input block detector, somewhere inbetween, with point decoders and tortoise motors to avoid.

 

 

[Andymsa]

9 hours ago, melmerby said:

Now try replacing 2 x 8 input block detectors neatly wired up, a metre or more apart with 1 x 16 input block detector, somewhere inbetween, with point decoders and tortoise motors to avoid.

 

 

I’m not sure if your referring to my wiring or your wiring, but I just rewired 8 detector boards spread 5 meters apart with no issues, and still maintained some sort of tidy wiring. 😀

[WIMorrison]

9 hours ago, melmerby said:

No Iain, they aren't

If you consider one side of the DCC system as high and the other low:

The high goes to the C terminal and some diodes are in series from there to the detection terminals which then go to the high rails of the various blocks, (the voltage developed across those diodes, when current is being drawn, provide the signal for occupied)

The capacitors go across those diode voltage droppers, (effectively they are a low pass filter)

 

The low DCC terminal goes to the low rail

 

 

Keith

 

Obvious really - my problem was that I was thinking about the DR5088RC wiring and not the DR4088xx wiring, and they are different. The DR4088 is always tied to one rail whereas the DR5088RC is actually provided with power from both rails. 

 

The DR5088RC also has a base sensitivity of ~10mA (needed for Railcom) and doesn't suffer with false occupation in the same way that the DR4088xx does.

[melmerby]

18 minutes ago, Andymsa said:

I’m not sure if your referring to my wiring or your wiring, but I just rewired 8 detector boards spread 5 meters apart with no issues, and still maintained some sort of tidy wiring. 😀

Mine

To do it neatly it would've needed a complete re-wire as the original wiring was heading for different locations to where the new detectors were placed.

I've generally replaced 2 x RS-8 with one DR4088, placed somewhere inbetween

I wanted to get it working as quickly as possible and have since revisted some of the wiring to tidy it up a bit, even changing which detectors some blocks go to.

[RFS]

4 hours ago, melmerby said:

Mine

To do it neatly it would've needed a complete re-wire as the original wiring was heading for different locations to where the new detectors were placed.

I've generally replaced 2 x RS-8 with one DR4088, placed somewhere in between

I wanted to get it working as quickly as possible and have since revisited some of the wiring to tidy it up a bit, even changing which detectors some blocks go to.

 

I've reached the stage where I understand why some people fit curtains to their layouts so as not to make what's underneath visible! My wiring is now a bit of a rat's nest after the upgrade to DR4088s but I console myself with the fact that it all works....

[melmerby]

I've had some bad luck recently as regards the layout.

First was the Lenz system's frequent dropping out when connected to Train Controller (using USB or LAN).

 

I've hopefully sorted that with the DR4088s, but now one of my MP1 point motors has failed! (frog switching microswitch) and a reverse loop module (LDT) has also gone faulty!

Fortunately I have spare MP1s and a new reverse loop module is on the way from Coastal DCC

[WIMorrison]

I think that this is first failure of an MP1  I have heard off, will James @DCC Train  Automation replace it under warranty? I think he is the UK importer.

[melmerby]

3 hours ago, WIMorrison said:

I think that this is first failure of an MP1  I have heard off, will James @DCC Train  Automation replace it under warranty? I think he is the UK importer.

I did a straight swap for another then had a closer look at it. 

I took the camshaft out and operated it manually, after a couple of operations it worked again.

 Maybe it just needed a bit of use? It's not had much use recently, whilst I've been module swapping.

[Anthony James]

Hello Keith,

I too am thinking about changing my set up from the Lenz system to the Z21 and also using Switch 8 for the turnouts.  How do they work, I have a few Tortoise machines but most are Hoffman slow motion AC ones, with a few Roco snap action ones as well in the hidden station, can you use all these with the switch 8?

 

Regards

 

Anthony

 

 

[melmerby]

7 hours ago, Anthony James said:

Hello Keith,

I too am thinking about changing my set up from the Lenz system to the Z21 and also using Switch 8 for the turnouts.  How do they work, I have a few Tortoise machines but most are Hoffman slow motion AC ones, with a few Roco snap action ones as well in the hidden station, can you use all these with the switch 8?

 

Regards

 

Anthony

 

 

Hi Anthony

The Switch 8s/Switch-Its are two terminal low current devices, designed really only for Tortoises, which stall at the end of the throw. The motors are permanently powered but consume little current (12-14mA typically at stall with 12v DC).

The Switch 8 operates by reversing the polarity to the motor and current limits at about 20mA or so, enough for two Tortoise motors in parallel, they will not drive higher current point motors

 

You might need a mix of devices, The Digikeijs DR4018 can drive DC motors that have an end of travel switch (e.g. MP-1)

I have mostly Tortoises with Switch-8s and a few MP-1s, The MP-1s use an Arduino based DCC point decoder

 

How are you switching the Hoffmann motors?

Apparntly the they are actually DC motors like a Tortoise but use AC through diodes to reverse the direction, (which you can also do with a Tortoise)

What about the Roco ones? Are they a solenoid type using a CDU or similar?

 

Using a Z21 you would have a choice of interfaces to operate the points, not just the DCC signal as with the Lenz, so there are Loconet devices available as well.

 

[Anthony James]

Hello Keith

 

thank you for your quick reply and the information.  This will need a bit of thought but I will work on, I have the Roco snap action point motors in my Shadow Station, and a mixture of Tortoise and Hoffman everywhere else, with just one or two Tortoise in hard to get to places, so we see how it all works out.

 

Regards

 

Anthony

[Anthony James]

Hello Again,

 

The Hoffman turnout motors are connected to my Lenz LS150 with three wires straight in, I gather that they have diodes inside them, and they work very nicely, especially with the speed control, the Roco ones are twin solenoids and again just have three wires straight in,  so I am trying to think of how to change them, as in some instances there are a combination of all three connected to the LS150 so at the moment I am now thinking of keeping the LS150,s as it will not require any wiring alterations, I would have liked to be able to switch a group of turnouts all at the same time, but it just does not seem I will be able to that at the moment, unless I can find a decoder that does what the LS150 does but with no delay.  I will check out the digikiejs and Roco ones to see what can be done.  I did notice with the Switch 8 that they use a DC power supply, another problem as I have all my turnouts on a separate AUX power source and do not want to power anything with the Track power.

 

Regards

 

Anthony

[melmerby]

Hi Anthony

The LS150 delay is the reason I ditched my LS150s. I was originally using them to operate Tortoises using two diodes having changed from Seeps . However the delay switching a string of turnouts made them virtually unusable as TrainController would send the command to change the points but there was a wait while each one operated in turn. I have a couple of places with long strings of turnouts (up to 7) and allowing 3-4 secs for each Tortoise to operate meant a 25 secs or so delay as they operated one after the other in sequence.

 

The Hoffman's are as, I understand it, also a type of DC stall motor but with inbuilt diodes to operate them from AC, using each half cycle in turn in the same way as Tortoises.

I know virtually nothing about them.

 

The original Switch-8 uses DCC for power but has the provision on the PCB for a DC power supply as an option, however for some reason the extra components needed were never fitted,

The Mk2 version can be operated from a DC power source as it does have the required components fitted.