Current-sensing Block Detection

Disappointed that no one has responded to OP.  Theses look potentially very useful

I can't imagine why these would affect the DCS signal.

Thanks for the input, John.

Was looking at the Azatrax site. They have a similar sensor that has the on-board relays in place for a good price. I'm going to order one and do some tests to see if there's an impact on operation.

@AGHRMatt posted:

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Was looking at the Azatrax site. They have a similar sensor that has the on-board relays in place for a good price. I'm going to order one and do some tests to see if there's an impact on operation.

I assume you mean the DBD2 which is about $10/channel which is quite attractively priced.

Did you have a chance to mess with it?

Does any make a "resistor wheel set" for 2-rail O gauge?

Made me think of how I cut the HO steel axle so I could insert a tach sensor wheel.  I used a brass sleeve to put it back together.  I was thinking one could do something similar to make a resistor wheel.  Cut the axle, attach resistor across the cut.  Then re-align with an insulated sleeve/tube. For 3-rail, just buy a powered truck.

@stan2004 posted:

I assume you mean the DBD2 which is about $10/channel which is quite attractively priced.

Did you have a chance to mess with it?

Does any make a "resistor wheel set" for 2-rail O gauge?

Made me think of how I cut the HO steel axle so I could insert a tach sensor wheel.  I used a brass sleeve to put it back together.  I was thinking one could do something similar to make a resistor wheel.  Cut the axle, attach resistor across the cut.  Then re-align with an insulated sleeve/tube. For 3-rail, just buy a powered truck.

What kind of sensors are those?

@A. Wells posted:

What kind of sensors are those?

I assume you're talking about the black body and clear body components.  These are garden variety IR (Infrared) emitter (clear) and detector (black).  The emitter sends a beam at the slotted wheel.  The detector picks up the beam thru the slots as the tach wheel spins.  Not shown of course is all the electronics to interpret the pulse timing and convert to a speed.

Or perhaps the package of the emitter/detector is unfamiliar.  Many/most IR emitter and detector shoot/detect the beam out the top so to speak.  These are typically called side-view or side-look IR emitter and detector.  I'm not sure there's a standard terminology for this style.  Just google it and you'll be overwhelmed with options!

@stan2004 posted:

I assume you're talking about the black body and clear body components.  These are garden variety IR (Infrared) emitter (clear) and detector (black).  The emitter sends a beam at the slotted wheel.  The detector picks up the beam thru the slots as the tach wheel spins.  Not shown of course is all the electronics to interpret the pulse timing and convert to a speed.

Or perhaps the package of the emitter/detector is unfamiliar.  Many/most IR emitter and detector shoot/detect the beam out the top so to speak.  These are typically called side-view or side-look IR emitter and detector.  I'm not sure there's a standard terminology for this style.  Just google it and you'll be overwhelmed with options!

I use the slotted variety.  One complete package, ready to go.  I finally got the ones I wanted from Mouser in December of last year after waiting for a whole year.  I 3D printed my own slotted wheels.  A little more bounce than I like, so I use two of the sensors at quarter offset.  I've also been using TI hall effect sensors as well with good results.

Right.  I remember trying to fit a slotted variety IR-pair with its inherent alignment...but had to use discrete parts because of fit issues - this is an HO truck.  I'm sure there are all kinds of packaging option now but I built this about 20 years ago!

I would have benefitted from a 3-D printer to make a slotted wheel.  As shown I fabricated a printed circuit board and used "vias" to make the holes precisely spaced around a circle.  Then I had to cut/file the circuit board in a wheel. 

Interesting you bring up Hall sensors which were also "novel" 20 years ago but are now mainstream.  For the OP's application, there are now AC Hall sensors that can measure current (no coils or transformers).  For example, Allegro makes a family of IC Hall sensors.  They are just a couple bucks a piece.  But you do need to surround it with a few components, mount on circuit board, etc.  These sensors would have even less effect on the DCS signal...not that the 1-turn current-transformer method does either.

@stan2004 posted:

Interesting you bring up Hall sensors which were also "novel" 20 years ago but are now mainstream.  For the OP's application, there are now AC Hall sensors that can measure current (no coils or transformers).  For example, Allegro makes a family of IC Hall sensors.  They are just a couple bucks a piece.  But you do need to surround it with a few components, mount on circuit board, etc.  These sensors would have even less effect on the DCS signal...not that the 1-turn current-transformer method does either.

I have similar ICs that I was working with last year to monitor RMS amperage and report back to a central control unit.  I didn't finish that project.

As far as the whole block detection goes, which was the only reason I looked at this topic, I've been working on another method of block detection (even as we speak actually).  Tweaking these things to absolute perfection is so painful.

@stan2004 posted:

I assume you mean the DBD2 which is about $10/channel which is quite attractively priced.

Did you have a chance to mess with it?

Does any make a "resistor wheel set" for 2-rail O gauge? . . .

Yes, that's the one I ordered. Haven't had time to test it yet, but it's inexpensive so if the experiment doesn't work it's not a great loss; if it does work it's a great bargain and reduces the hassle factor for block detection for TMCC/DCS/AC-Conventional (they won't work with DC, though they might detect half-wave rectified DC).

Insulated axles are actually pretty easy with an Intermountain axle since they  are single-insulated. All you have to do it solder one end of a 10K-Ohm resistor to the back of the insulated wheel and the other end to the axle. The current draw is minimal but should be sufficient to trip the detector. The beauty of this method is that you can have a lot of resistor-equipped cars in a train and the overall current draw is minimal. I believe Intermountain actually sold them for their H.O. cars but they never made it into O scale.

Did you ever test the DBD2?

Brendan

Not yet. Got tied up on other projects related to moving, will be setting up the test bench soon.