Got yet another one for my Forum friends: Is there an easy way to add further adjustment to the sensitivity of Circuitron crossing circuits? I am in the process of install a 3 track crossing on my layout. Two of the four circuits are too sensitive in that a shadow from 3 inches above the senors trip it. One another circuit two sensors trip but the third one doesn't trigger. And none of the sensors on the fourth trigger at all. (The 12 sensors are wired in parallel as needed.)
As usual, any suggestions that can be provided would be most welcomed.
Is that with the sensitivity maxxed out? Do they even support having 12 sensors? The combined parallel load of 12 sensors may exceed the limits of the circuit. It's nice to want to save money when there are multiple tracks, but the GCP isn't really designed for that.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
On a couple of the circuits the adjustments are very close to the circuit being activated. I was wondering if a resistor could be put in the "legs" of the circuits to compensate a bit.
In the alternative, what system would work for this application?
FRRYKid Got yet another one for my Forum friends: Is there an easy way to add further adjustment to the sensitivity of Circuitron crossing circuits? I am in the process of install a 3 track crossing on my layout. Two of the four circuits are too sensitive in that a shadow from 3 inches above the senors trip it. One another circuit two sensors trip but the third one doesn't trigger. And none of the sensors on the fourth trigger at all. (The 12 sensors are wired in parallel as needed.) As usual, any suggestions that can be provided would be most welcomed.
What we need, quickly, is a sketch of precisely how he's wired the sensors together, and where he has the pots in the Circuitron set.
I not sure how exactly to describe how I have the pots set. I also don't have a real easy way to sketch what I've got but I will try to describe the way I have everything wired.
For the common (SD on the diagram), each run has the wiring starting on D running to A (L to R) on each track. The wires from the sensors drop down vertically to connect to a wire that runs horizontally. (They don't connect directly to each other.) Then on the right hand end, those runs are then connected with a single wire intersecting the three runs to connect the circuit to the board.
For each of the control circuits (D to A running again L to R), the other wire on the sensor again is dropped and connected with a wire running from back to front for each letter sensor (D3, D2, D1, etc.) and to the respective stub on the board. Again no sensor is directly connected to another.
I was told that for this particular use I couldn't connect the sensors in series as they wouldn't detect properly. (Prior post http://cs.trains.com/mrr/f/744/t/281908.aspx)
The only thought that I had with the sensors that don't sense at all (D3, A1, A2, and A3) is that something is broken in the sensor itself.
I hope this helps clear things up. If someone can suggest how I might describe the pots, I can post the locations of those as well.
Easiest way to start on the 'pot' question is likely to be taking a good high-resolution shot of the Circuitron board showing the current pot positions clearly, and people with experience will take it from there.
Randy and some others can tell you how to test these sensors -- I did not think it was hard, just dark resistance with a multimeter followed by readings in various degrees of light. If these are consistent across the batch you probably don't need a spec sheet from a source like Randy or Ed to compare 'factory' values.
You might want to ask a little more about how the Circuitron actually works to make better sense out of troubleshooting this configuration.
It's easy enough to test each sensor - just hook up one at a time and see if it triggers when the sensor is blocked. There's basically nothing to them that could break, unless you smashed it with a hammer, or held the soldering iron on so long it melted. And they aren't nearly as sensitive to that as say an LED, an LED will be much more easily fried by overheating with the soldering iron than the sensors.
If you look at the prior post you referenced you'll see my long dissertation on how photocells generally work. Frankly, I have not encountered a photocell which has a higher resistance when light hits it and a lower resistance when light is blocked from it!
Here's an application note from Circuitron (http://www.circuitron.com/index_files/AN/an-0003.pdf) which covers multiple sensors going to a single detection input. You can see on the righthand side of the drawing that the two sensors are connected in series. That is consistent with the way our products work too.
rrinker It's easy enough to test each sensor - just hook up one at a time and see if it triggers when the sensor is blocked. There's basically nothing to them that could break, unless you smashed it with a hammer, or held the soldering iron on so long it melted. And they aren't nearly as sensitive to that as say an LED, an LED will be much more easily fried by overheating with the soldering iron than the sensors. --Randy
None of the connections are soldered. They are very tightly twisted and the connections on the sensors are also sealed with heat shrink tubing.
That could be part of it. Twisting wires around the legs on the light sensor is not going to make a consistently good connection, heat shrink or no heat shrink. They tend to not fail, and if you never soldered them to thw wire, even less likely that you have a bad sensor. But still, you can try them one at a time and verify each one works.
Randy, if he doesn't like to solder do you think we could get him to invest in a good wireweap tool and learn to use it well?
Have to find some of those old clip posts with wire wrap pins, wire wrapping around a round wire lead doesn't do much for it.
Overmod invest in a good wireweap tool and learn to use it well
invest in a good wireweap tool and learn to use it well
???? Never heard of that.
Yeah don't worry about it, just a couple of old timers remembering past options. Twisting the wire around is fine to test, but once you get it working you're goign to want to solder those connections for reliability.
I still suggest testing each of those 12 sensosrs one at a time, if they each work individually, then none are damaged (and it's not likely they would be damaged anyway, they're not particularly sensitive components). But if it turns out one doesn;t work, or requires a vastly different adjustment to work compared to the other 11 - it could be one of the wrong value that got into your oder by accident. They do have ratings, generally a dark resistence and a resistence at a certain light level, and yes it will matter because the rest of the circuit is designed around those being some particular range of values, and you can get the sensors in various values. Mixing just one of the wrong range in a bunch of parallel connections can mess up the operation.
SO test them one at a time, if all else is the same except for the sensor, you shouldn;t have to adjust the potentiometer each time - set it for one sensor to work, then swap out the sensor keeping the light source, distange, angle, etc all the same. Any sensor witht he same value should work at the same setting or just a tiny tweak. If one requires you to move the potentiometer more than a fraction, something's up with that one.
rrinker I still suggest testing each of those 12 sensosrs one at a time, if they each work individually, then none are damaged (and it's not likely they would be damaged anyway, they're not particularly sensitive components). But if it turns out one doesn;t work, or requires a vastly different adjustment to work compared to the other 11 - it could be one of the wrong value that got into your oder by accident. They do have ratings, generally a dark resistence and a resistence at a certain light level, and yes it will matter because the rest of the circuit is designed around those being some particular range of values, and you can get the sensors in various values. Mixing just one of the wrong range in a bunch of parallel connections can mess up the operation. SO test them one at a time, if all else is the same except for the sensor, you shouldn;t have to adjust the potentiometer each time - set it for one sensor to work, then swap out the sensor keeping the light source, distange, angle, etc all the same. Any sensor witht he same value should work at the same setting or just a tiny tweak. If one requires you to move the potentiometer more than a fraction, something's up with that one. --Randy
Pending Mom's plans for Tuesday or even late afternoon or evening Monday, that is the plan.
The main reason I don't solder anything is that I'm not very good at it and I don't want to solder over my head. (The whole system is under the layout which is roughly 36" high.) I have used wire glue at points for some things, however.
FRRYKidThe main reason I don't solder anything is that I'm not very good at it and I don't want to solder over my head.
Now, it does have to be said that I have never used anything but downhand position for soldering and would be very, very circumspect trying to do it 'over my head' But that is precisely why the idea of modular plugs and wire harnesses was invented ... and why learning how to sketch wire layout can be important. You do all the soldering and subsequent shrink-tube and paint-on insulation in the harnesses, at the bench, including any pigtailed plugs from things like the physical crossing lights that will go under the layout, and you color-code and/or tag all the wires and plugs so you can tell 'what's what' under the layout. All that happens subsequently in installation, maintenance, and troubleshooting involves easily-identified, easily-accessible plugs and touchpoints that can be field-separated and reinstalled -- ideally without tools.
Indeed. Solder at the bench, but solder a length of wire to each sensor and put a plug on it. And solder wires to the points on the crossing controller at the bench, and put matching sockets on it. Or you can alwyas use screw terminal strips - solder wires, no plugs or sockets, at the bench, under the layoutm insert the bare wire end into the screw terminals.
Either way this will be a MUCH more reliable connection than any of the wire glues or just wrapping the wire. It should be fairly straightforward - do the sensors first, as while they can be damaged by holding the iron on too long, it's a REALLY long time - it's a pretty easy solder joint with limited risk to damaging anything via poor technique. The circuit board side needs you to solder fairly quickly - it's not liek if you take 2 seconds it will damage the board because you had to keep it under 1 second, but you can't hold the iron on for a minute at a time. Using screw terminal strips, you will only need to solder one pair of wires to the board - the parallel wiring of the sensors occurs at the screw terminals.
I will say, in many years of this, I solder most everything, including under the layout, and I've never dropped solder on myself. You only get a big blob that falls on you if you feed in far too much solder.
Two tricks to best success - use 63/37 solder, not 60/40, and make sure your soldering iron tip is shiny clean. When it gets blackened, it slows heat transfer which means you end up holding it on far longer than you should to get the solder to melt. When clean and shiny, it's nearly instant with small thin wires or components, a little longer with thicker wire. DO practice a bit if you are unsure. There are numerous videos to watch. Some of the things I see are a little "how ya doing" as our fruiends Down Under would say, but they still get the job done. Strive for a neat clean joint, but it doesn't have to be absolutely perfect to work. An average solder joint will be better than wire glue.
Mentioning modular plugs and such:
A lot of the connections I have on the layout, especially where the wiring goes past a layout section, have solderless slide connectors on them. Where I have the problem of using this idea with the wiring on the crossing sensors is that the wire is 30 AWG. I don't know of any wireless connectors that go that small. All the rest of the wire is about 16 AWG. (Wiring purchased from my local NAPA as no other place in my little town has wire that small.)
What I did when using crimp terminals on small bell wire was to take a short 'blind' length of stranded 18-gauge lamp cord (which used to be easily available in hardware stores) and strip/retwist ready for crimping, then insert the stripped end together with the bell wire into the connector. This crimps all the copper together for massive contact area inside the terminal base even if crimping is a bit 'impromptu' or the wire end isn't tinned.
Then you can make up a strain relief with the usual kind of materials at the 'back' of the terminal -- this doubles as a handle to help separate them. By joining the little piece of 18ga to the bell wire this greatly aids against kinking where small-gauge solid copper goes into a crimp (or any other) type of terminal.
Any other kinds of stripped wire ends will likely work as well. It looks a bit strange but I assure you it works.
You have to look at online ordering solutions for small stuff like that. Some useful small connectors are available from various hobby suppliers.
And for sensors liek this, where you have a lot of wire runs, telephone/network cable comes in handy for reducing the wire mess. It's a bit larger than #30, so easier to handle, and you get 4 pairs in each cable - so you could effectively have one cable connecting 4 sensors, instead of 8 individual wires that you need to bundle up.
With the way the diagram showed how to wire, I'm not exactly sure how I would have used a telephone cable for this situation. With a lot of practice, I've gotten the hang of working with the 30 AWG wire. The wiring is not that much of a mess, especially given that I remembered to color code it. The control (A, B, C, D) are one color and the SD is another.
I'm still not sure it's supposed to work as yuou are trying to do. Which unit do you have, and a sketch of the track would help.
The Circuitron catalog with application notes is here:
302CAT.pdf (circuitron.com)
App Notes 101-105 cover crossing flashers, single track and multi track. The multi track option shows using multiple DT-1 detectors feeding one FL-2 flasher. The only multi track option that uses only one detection unit is if it's a single track in one side, and a siding ont he other side, so there are 2 tracks one side of the grade crossing, and 1 track on the other side. That's App Note 105, and the sensors are NOT in parallel, they are in series. From SD which is the sensor common, the wire goes to the sensor on track 1, then to the sensor on track 2, then finally back to the detector S1 or S2.
Though if you are using DCC - I suppose you are using the DF-2 or DF-3? Of COURSE the instructions for those are not online, but unless it explicitely says the sensors get wired in parallel I'd almost assume not, because none of Circuitron's other optical sensors get wired in parallel for multiple sensors.
The DT-1 and DT-2 are really only for DC, because they use the track polarity to determine which sensor is the start and which is the stop. The DF-2 and DF-3 use additional sensors and a microcontroller to figure out which way the train is going based on the order the sensors are blocked and thus need no indication from the track as far as direction is concerned.
As to the system question, I'm running DC.
As I really don't want to spend another $80 or so (Two DT-1s and a piece of track to hold the DT-1s.), I'm just about ready to take all the sensors and DT-1 out and figure out how to just use the flasher unit (FL-2) to light the crossing lights. (A pair of Model Power units.)
The C sensors have now decided that they want only to work intermittenly. I also checked the D sensor that didn't want to activate and I used every test I could think of with my electrical tester. The results showed me nothing. The resistance was the same on a working sensor as the non-functional sensor. The voltage came across the same as well.
FRRYKidThe resistance was the same on a working sensor as the non-functional sensor.
Make a little table: number the sensors temporarily, and log what all their resistances are when covered. Then shine a light into each at a consistent angle and record their resistances again, for comparison. Any that don't show resistance going down when illuminated aren't working. Any that show infinite resistance no matter what the light aren't working.
My guess is that a couple of these may not show the same degree of resistance drop in light that the others do, but until we know that (and have the values for the specific components you're using) we're fiddling in the dark and need to see the sheet music.
Well if you are using the DT1 - multiple sensors most definitely do not go in parallel. App note 104 and 105 show this, but for multiple mains, you absolutely need multiple DT1's for it to work realistically. But you could probably get by with having multiple sensors wired like App Note 104. But I wonder how many can be in series before it won't work at all. They show two in App Note 104. 4 in series may render it not operational.
Other option is to return it all and get the Logicv Rail Grade Crossing Pro, which handles one track AND has the flasher part, and then their add on detection boards for each extra track. The GCP is less expensive than the CIrcuitron DT1 plus the flasher board. ANd operates more realistically - more like the DT2 which is a lot more expensive than the DT1.
If you have to have multiple tracks trigger the crossing, that's the way it goes. Or put the crossing with flashers elsewhere where there is only a single track to cross. Or dump it all and just put a pushbutton on the fascia that you press and hold when you want the crossbucks to flash.
rrinkerBut I wonder how many can be in series before it won't work at all.
As you add detectors in series, both the 'dark' and 'light' resistance go up. If the pot is not set in the range that can compare the two values reliably, the device will not function correctly. Now, the resistance difference between light resistance and dark resistance proportionally increases, which technically would make for higher discrimination as the total resistance increases. But if the aggregate 'light' resistance exceeds what the 'dark' pot range can adjust for, the board will never sense enough of a drop in resistance for it 'not to be dark': either the board will have its channel 'stay on' as if detecting a train, or the sensitivity even in strong light will be so fidgety that shadows or passing insects trigger the 'dark' response ... which as I recall was one of the early reported symptoms.
Be easy to test what the board can accommodate by connecting up a resistor decade box, and see what the resistance corresponding to points on the range of the adjustment pot(s) might be. That will give you a good idea of what combinations of 'dark' and 'light' tested sensor resistance would produce...
I made a boo-boo eariler. I have the DT-2 not the DT-1.
In looking at the Logic Rail system, I see something that I like as I want to put some night operations into my layout and the Opto-sensors don't work in complete darkness. Too bad I don't know a way to put some sort of I/R sensor on a Circuitron board.
I don't see how the Circuitron one is any different, they are the same type of photocell detectors. Without a light beam to be broken so there is a change in resistence, they won't detect. Or are you using some other type of sensor than the ones Circuitron sells? That could be a problem as well, the circuit is designed for photocells.
rrinker I don't see how the Circuitron one is any different, they are the same type of photocell detectors. Without a light beam to be broken so there is a change in resistence, they won't detect.
I don't see how the Circuitron one is any different, they are the same type of photocell detectors. Without a light beam to be broken so there is a change in resistence, they won't detect.
I will disagree with you that Opto-sensors and the I/R sensors are the same. The opto-sensors need some sort of light to work. An I/R doesn't need light to operate as it uses a beam to detect motion. (Think the automatic doors at your local grocery store or the security lights in people's yards.) No, I'm by no means an expert. I looked it up just like everyone else. https://www.arrow.com/en/research-and-events/articles/understanding-active-and-passive-infrared-sensors and https://www.fierceelectronics.com/sensors/what-ir-sensor
rrinker Or are you using some other type of sensor than the ones Circuitron sells? That could be a problem as well, the circuit is designed for photocells.
Or are you using some other type of sensor than the ones Circuitron sells? That could be a problem as well, the circuit is designed for photocells.
As the system stands right now, I am using the brown ellipsoidal Opto-sensors that Circuitron sells.