Are they reliable?

I'm not sure if this is the right place to ask, but I intended to order a couple of Irdots this week.

I have just read the topic about turntables and Irdots were mentioned there as being occasionally unreliable.  I was planning to use them as stop contacts to get better accuracy at the end of long blocks, but if there is any chance of a train over-running the Irdot then I don't want to risk them.

What's the general experience among those who have used them?  Do they respond quickly enough to stop all trains consistently in the same position?  I don't want to have to modify engines or stock in any way.  Are they accurate and reliable when switching off (Irdot-1)?  I was hoping to use them to stop the rear of all trains at the same spot with greater precision than TrainController's timing to shifted markers.

Regards,

Brian

Brian, I had mixed success with Heathcote IRDOTs as some locos had to be painted silver/white underneath to reflect the IR & it was dependent on location - tunnels gave hiccups. But I did find that if the transmitter & receiver were in a line facing each other therefore always on and the breaking of the IR path by a loco/ rolling stock, worked all the time. In hiding storage, this is easy as one is mounted over the track. In the open, usually in buildings, etc. a bit of experimentation is required.

 

 

Typo error corrected by Sol

 

I have ordered a couple today  from Heathcote Electronics so hopefully  I will be able to answer your question in the near future. At £14.50 each they are not cheap by any means so hopefully there wont be any problems with them but as its the first time I have used them I am not sure what to expect.

Tried them yrs ago. Did not like them.

 I much prefer thru the rails block detectors. All my signaling is done with these.

Ian

I've had no problem with them mounted beneath the board as per the standard instructions. They work both when locos and other stock pass over them and also from the wave of a hand above the track. They use a pulsed frequency driver so that the receiver is not fooled by other light sources such as lamps and daylight. In theory, such a system should be very reliable.

If you would like another opinion, you might wish to contact the McKinley team. www.mckinleyrailway.com They now have a demo layout they take to shows and they show the use of IRdots running with block current detectors. I am sure that they will have knowledge of reliability. 

Hi Brian
I have them in my hidden sidings and I find that they respond in the way you are looking for ie stopping immediately at the end of an occupancy section. I did find that initially (in DC) they were not responding consistently but I found that folding a matt black card over the sensor area as an "internal tunnel" meant that only the loco reflections caused a response. I did have a few challenges programming Traincontroller but now OK. By the way I also found it useful wiring the led to a small mimic board close to the hidden sidings area to give me a further indication of occupancy. Hope that helps.
Chris

Thanks, everyone, for the useful advice and comments. Clearly it's worth trying one to see how it goes. I am encouraged that two top class layouts, the McKinley group (Geoff: Thanks for the link) and Mangarth, are using them successfully. It may be a while before I install one because I am having unexpected problems in working out how to integrate optical detectors (all engines zero contact distance) with current sensors (front contact distances varying individually around 0.5" to almost 3") within TrainController - but that's another story.

Regards,
Brian.