I don't know off hand which wire it was, but it was in the cable to the 6015/7 boosters. I can't find my schematics at the moment, but that should put you on the track of it.

thanks perz. I assume this diagram is probably from some site explaining how to drive the digital signal directly from a serial port, and from it we can see that pin 5 is the stop signal line.

i.e. it is not showing anything about how to introduce the false short signal. I presume shorting pins 4 and 5 need to be bridged.

Ummm... using JMRI/WiThrottle Lite of course. I forgot to include that.
Tom

Cookee, I suspect Tim may have this issue with his layout, given it is most likely much larger than Dale's (2300 sq ft)

Shorting out the track is NOT a good solution. There is a chance of frying the booster or IB itself. I also have fuses in the supply to these devices and they sometime blow before the booster-IB stack shuts off. I dont want to have to replace a fuse every time I make an emergency halt, and certainly dont want to fry the hardware either.

Hi Dale,

Appreciate the response but I'm really none-the-wiser. Right from the early days of Digital there was plenty of information that short-circuits need not be feared on a digital layout because the reaction/shutoff time of the controllers was so fast that damage would not result.

I appreciate that the original query was probably more based on stopping an "about to happen" incident in which case what you really want is a button that simulates the 'Stop' button on the controllers. If equipment is so fragile (or poorly designed) that a derailment, or something dropped across the track causing a short actually fries the equipment, I would seriously consider avoiding those products.

I've shorted many times through derailments and never has any item suffered resulting damage.

Derailments on a model railway are a fact of life and the control equipment should be absolutely impervious to it.

We can of course agree to disagree, we're all gents here afterall but I'd be REALLY interested in a factual proven incident of a typical short-circuit actually causing damage. The only time I could see it not possibly being effective would be a derailment that unfortunately happened across an isolated section between two controllers/boosters? - even then, the designers should still be anticipating the possibility of the worst-case scenario.

These are afterall products aimed at a market which includes children who make mistakes.

Given that your recollection is from maybe 20 years ago or thereabouts, I wonder if it might have been an article in Tom Catherall's Digital Newsletter or similar?

Interesting topic all the same. For me, I'd still pursue a button to short the track (pending further good reasons why this is a really bad idea)???

Steve

I run an IB and two boosters. Each has a fast blow fuse on their power supply.
I add the fuse because I would rather replace a cheap fuse than fry a booster or the IB.

My tracks are are well connected, i.e. if there is any short, lots of power can flow. On a number of occasions, a short has resulted in the fuse blowing.

Since there is a digital signal line that indicates that there has been a short, it is obvious that one should use that rather than producing an ACTUAL short which forces one to rely on the current cut off of the devices, no matter how well they are designed. Shit, it may even be cheaper to lets the trains collide than short out the electronics!

Anyway I am still on the hunt to find out exactly which line of the cable should be grounded.