Search found 64 matches

by Albert
Mon May 11, 2020 10:56 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Thanks for the comments. :-)

I've got my prototype of your circuit built and my 'scope has arrived. Now I need to start debugging my build.

Wish me luck!
by Albert
Sat May 09, 2020 10:28 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Thanks, Rob.

I'll see about getting one to test. Did a little research and apparently they can be a bit erratic but definitely worth trying.

Cheers
by Albert
Tue May 05, 2020 2:08 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Thank you Rog. I had a nasty feeling that would be the answer. I've bought Roger Amos's Electronics book and treating that as a basis for learning enough analogue electronics to make sense of this and future projects. I actually had a few zener diodes in my bits box, so I'll be sure to add them . I ...
by Albert
Sat May 02, 2020 12:17 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Me again, Rog. So far I have built almost all the 'inside of the box' circuit you provided apart from the last couple of resistors (R4 & R5) that I guess are just there to deliver a voltage around 4 or 5 volts to the OCC line to an Arduino digital in. Originally I planned to bodge together sever...
by Albert
Tue Apr 28, 2020 10:36 am
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Hi Rog My assembler days are far behind me now. At that time I found that for my particular needs software couldn't keep up with the data flow, so I switched to hardware for real-time video digitizing. Nowadays, of course software runs rather faster than Z80 assembler could deliver!. Since then, spe...
by Albert
Sat Apr 25, 2020 9:41 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Thanks, Rog. Switch debouncing takes me back to my earliest assembler days! I'll certainly try the software approach. I'm just concerned that it might add too much overhead to the main loop. I'm not too sure about the capacity of an arduino. Still, I can always go over to hardware if the system gets...
by Albert
Sat Apr 25, 2020 3:15 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

One problem you might encounter with multiplexing however is the need for a filter in software (see scope shots earlier this thread) the dwell time on a single section would have to be long enough for the filter time-constant, alternatively if you have plenty of memory maintain a filter per section...
by Albert
Fri Apr 24, 2020 11:23 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Thanks for all the help. The aim of a multiplexed system is partly to reduce the number of input pins required on the Arduino. I'm currently planning on using 6 blocks on my development track. Using an 8 channel mux needs four pins, rather than six, so not a big saving but my next planned project wo...
by Albert
Mon Apr 20, 2020 10:36 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Hi, fourtytwo I'm back! I had to wait for some components and then other bits of life got in the way. Still trying to understand what goes on. Some simple (I hope) questions about your diagram of 'Just the inside of the track circuit box, nothing else'. I am concentrating on a uni-directional setup ...
by Albert
Fri Apr 03, 2020 1:47 pm
Forum: Baseboard Design and Construction
Topic: BASEBOARD - another way to consider
Replies: 21
Views: 5689

Re: BASEBOARD - another way to consider

I'm glad it came back, anyway, beacause I missed it the first time round. One thing anybody using this technique ought to beware of, though, is that the silver foil finish seen on that type of board is actually conductive, so things like droppers need insulation. I have a sheet of this that I use fo...
by Albert
Thu Apr 02, 2020 7:58 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Hi, fourtytwo.

Oh, well. Thanks anyway. I'll get on with some other stuff.

Stay safe
by Albert
Thu Apr 02, 2020 2:43 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

I am afraid the 2K2's in the above diagram don't do quite what I had intended as your L293's are never truly off (tri-stated) unless the EN pin is driven low. I'll have a play anyway. I must admit that my understanding of the operation of the L293 is that it is effectively a 'high frequency' relay,...
by Albert
Wed Apr 01, 2020 5:15 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Thank you, fourtytwo, for your patienceand forbearance..

You're a gent (probably, given the demographics of railway modelling; but you know what I mean).
by Albert
Wed Apr 01, 2020 11:10 am
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

Hi Albert I foresee a potential problem in your application and that is these track circuits are designed to be used in a common return system where the common return is system ground. The first important point is the track circuit bias must always be +24V relative to common return. The OCC signals...
by Albert
Tue Mar 31, 2020 9:30 pm
Forum: Electronics
Topic: Track Circuits (Train on Track Indicators.
Replies: 42
Views: 2055

Re: Track Circuits (Train on Track Indicators.

I found the quality issue, it was in color, I have now printed it in monochrome and it seems much better. The original diagram was done over a year ago and either I had run out of color ink or some other reason printed it in monochrome and I eventually figured that was the difference :oops: Thanks....

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