Point motors and Hornby accessories decoder

[Saintnick1974]

Hi all, I wa

[Chrissaf]

Seep point motors and Hornby R8247 decoders have been recently discussed in some detail. I suggest you carefully read ALL the posts in the thread below. There seems to be an issue reported that puts some element of doubt on the ability of the R8247 to fire two Seep point motors that are wired in parallel. For example when operating a pair of points forming a cross-over between one track and another. The thread also indicates that singly, the Seep operate OK with the R8247. These point motors do however require some skill to ensure 100% alignment as part of the installation method. Perfect alignment is critical for any Solenoid point motor and the Seep in particular.

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https://www.hornby.com/uk-en/forum/point-motors-33742/?p=1/#post-342238

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See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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[ColinB]

I am not surprised a R8247 does not operate two points together. I had issues with my analogue system not being able to do this reliably, sometimes it worked sometimes it didn't. So I then bought some Peco low energy point motors and the same thing happened although not so often as with the previous normal Peco point motors. Maybe if I had increased the CDU capacitor size it might have got better, but I decided to use separate switches. I would imagine the R8247 has less power than my CDU unit, and the whole idea of the R8247 is to power them separately and switch them one after the other. I think the Seep point motors use about the same current as the low energy Peco ones. I am not an expert on inductors, but I assume it is something to do with the coils differing slightly.

[Saintnick1974]

Thanks for that. I have 7 points so have bought 2 decoders, but i do have a crossover, which i was going to try and wire together obviously, I am also going to make the fittings adjustable to get the correct alignment.

[96RAF]

I have several paired points that are fired by R8247s. What you will find is that if the motors are disimilar types and/or makes then one of them will hog the power and the other will fail to fire.

 

Seeps are notorious for requiring exact installtion alignment as Chris says, which can affect firing as singles so if paired then the problem is increased.

 

The way round the problem is to use the R8247 pulsed output to pull in relays to port the output of a hefty external CDU direct to the motors. 

 

R8247 has qty four 4700μF capacitors so it will fire paired motors although the official Hornby policy is that they will reliably fire a single motor. Folk may wish to compare these component values with those fitted to their CDU.

 

What is more important is the pulse duration, which is 100mS default on R8247, but can be adjusted and 500mS will give a better chance of firing a tardy motor, taking note that 800mS is the absolute max pulse duration to avoid solenoid damage and that regardless of the duration set you can only drain a capacitor until it is empty then it has to recharge.

 

I would point out (sorry) that the new basic DC controller R7229 only has qty two 2200μF capacitors and the new DC HM6010 point and accessory controller (PAC) has qty four of the same component and they fire single well installed points OK.

[ColinB]

I think you will find the 800 mS is probably to protect the R8247 rather than the solenoid, I took mine apart and looking at the driver there is no heat sink and is being driven by a huge charge bank, so I suspect it cannot carry much current for very long. That is probably why Hornby only recommend driving one solenoid, just in case the user has a Peco PL10 point motor attached.

[96RAF]

Don’t try this at home Colin as this is not fully bench proven, but if you short R15 in an R8247 you can actually get 1-amp output from it, although a better way would be to dedicate one port to high output by use of a suitable output transistor (Q1 to Q4). This is how it is done in the new HM6010 PAC, for turntable drive. Although this is a DC layout point and accessory control device, it can according to the blurb be powered either by a 12 V DC input or a DCC input.

[ColinB]

It is difficult to read the number off the IC, but if it is the device I looked up, it is rated at 6 amps, which I find very hard to believe. I suspect that is only for a very short period. I have got two of these devices that came with my Elite. I have about 40 plus points so DCC is not really on, perhaps in the future, so they have sat in the box. My Heljan turntable works directly off DCC using the accessory commands, that is impressive and so incredibly quiet. I might use the Hornby accessory modules to power latching relays to power the turntable outlets, so the power is applied after the turntable moves to the position. I think with my Fleishmann you can set events to daisy chain commands, reading the manual I think the Elite can do it as well, you probably know better than I do. 

[96RAF]

Wandering off topic slihtly Colin but I have exactly the same problem with running a Tt from the new HM6010 PAC in that the port putlet has 3 x connections , positive and left or right switched negatives. The Hornby TT has a 2 x wire rotation motor connection normally controlled by an analogue speed controller and direction switch.

 

My suggestion was also to use a twin relay module to convert the PAC/PAD directionsl output to a suitable control method for the Tt rotation motor.

 

Yes the Elite can run a sequence of DCC ‘event’ commands but it can only send them to a Sapphire decoder.

[96RAF]

Wandering off topic slihtly Colin but I have exactly the same problem with running a Tt from the new HM6010 PAC in that the port putlet has 3 x connections , positive and left or right switched negatives. The Hornby TT has a 2 x wire rotation motor connection normally controlled by an analogue speed controller and direction switch.

 

My suggestion was also to use a twin relay module to convert the PAC/PAD directionsl output to a suitable control method for the Tt rotation motor.

 

Yes the Elite can run a sequence of DCC ‘event’ commands but it can only send them to a Sapphire decoder.