Track Contact to trigger switches

Slawman

Slawman

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Can someone advise me as to why you would use a digital track contact (ie. Massoth 8420502) as opposed to a simple un-powered reed switch? all my locos have magnets and I am running the contact to a switching decoder which simply needs a short to trigger the programmed switch.

Aside from the additional costs you also need to power these things so there must be some benefit I am missing......


8420502 Digital Track Contact
 
I am in the same boat Greg (or perhaps on the same train :)). I have also had reeds last for years. 1.70 will get me a reed to do what i want compared to $50 for the Massoth unit.

Is the Massoth unit directional?
 
it appears that it is a hall effect sensor, that requires power, and has an open collector output, i.e. taking the "input" to ground with triggered.

So, "directional" is not really how you characterize an open collector npn transistor, it needs to be put in the circuit where it switches power to ground.

More to what you are asking, it's not a general purpose on off switch that could be put in a circuit anywhere.

Greg
 
Thanks Greg, can you suggest a contextual example where this device would be needed over a reed? The manual talks about it providing a "pulse" when triggered? The reason i am asking is because i am about to finalise an order from the US (i am in Australia) and i will grab a few if they might become useful as I expand my layout...

Interesting Hall sensor pros and cons from Wikipedia (especially the North/South feature, directional?):

A Hall effect sensor may operate as an electronic switch.
  • Such a switch costs less than a mechanical switch and is much more reliable.
  • It can be operated up to 100 kHz.
  • It does not suffer from contact bounce because a solid state switch with hysteresis is used rather than a mechanical contact.
  • It will not be affected by environmental contaminants since the sensor is in a sealed package. Therefore, it can be used under severe conditions.
In the case of linear sensor (for the magnetic field strength measurements), a Hall effect sensor:
  • can measure a wide range of magnetic fields
  • is available that can measure either North or South pole magnetic fields
  • can be flat
 
I'm late to the party as usual. I have found reed switches to be reliable in electro-mechanical devices other than trains. AND cheap enough to diagnose by replacing the suspect switch.
Just my "Luddite" opinion.
 
Biggest advantage is the lack of contact bounce.. - Especially useful for chuff sensing!
More robust to the physical environment, as has already been said.
 
Slawman said:
Can someone advise me as to why you would use a digital track contact (ie. Massoth 8420502) as opposed to a simple un-powered reed switch? all my locos have magnets and I am running the contact to a switching decoder which simply needs a short to trigger the programmed switch.

Aside from the additional costs you also need to power these things so there must be some benefit I am missing......


8420502 Digital Track Contact
Click to expand...

Not being an electronics expert (and also not having the time or inclination to become one) I have used these track contacts in conjunction with other Massoth products - eg Switch deciders, feedback modules - to implement a few things such as automated point operation, automated driving characteristics.

Whilst the contact devices may be expensive in relation to the collection of individual components that go into them, and I appreciate it’s possible to “build your own” gadget that does the same thing, the Massoth devices work “out of the box” so they have allowed me to get things working quickly and reliably. There is also a low risk of me blowing up a more expensive item such as a feedback module by connecting a homegrown device that I don’t fully understand.

For me, this is why I don’t object to paying the retail price for them.
 
Hi Phil,

I take a similar approach. The main issue I am curious about with these detectors is that they are powered so you need to run additional wiring and connect them up. For all the bits I have played with to this point (feedback modules, braking modules, automatic switching) I can use a contact close ie. no power.

I was hoping someone could point out something that would not work unless I use one of these detectors so I don't end up building my automation around un-powered triggers only to find I can't do XX or YY (it wouldn't be the first time) and it would make sense that they are required for something specific given the extra cost and installation requirements. Maybe it is just reliability.

I bought a few in my last order and will use them alongside the un-powered sensors and keep an eye out for any difference.
 
Oops - just realised you mentioned the 8420502 device which is different from the ones I’ve been using (these are the 8420602 model). Looking at the manual for the 0502, the device seems similar to the LGB track contact (17100 I think). I tried a couple if these a while ago and they didn’t seem to work the way I wanted which is why I went to the 0602 model. So basically I’ve wasted your time reading this - sorry!

Note to self, take your tablets every day BEFORE you check you email...
 
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