DIY Resistor Wheelsets for Block Occupancy Current Detection | No Soldering!
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- เผยแพร่เมื่อ 18 พ.ค. 2024
- In this video we're adding resistors to rolling stock wheels so that they can be detected by block occupancy current sensors.
This is really important if you plan on using automation tools which rely on accurately knowing if a block is free or not.
I put off adding resistors to my rolling stock wheels for ages because I thought it'd be hard work and I didn't want to risk damaging my models, but it's actually really easy and it's (almost) completely reversible.
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Chapters
00:00 Introduction
02:17 Resistors
04:56 Gluing
07:22 Electric Paint
08:30 Cleaning
10:12 Painting
14:10 Multimeter Testing
15:31 Does it Work? - วิทยาศาสตร์และเทคโนโลยี
I watched this when it came out first and ordered the pen straight away. Just watched your video again today as I got the pen in the post (from China) this morn. Great video. Can't wait for part2 of your build.
Thanks Rob, useful to know about these options for a later date for automation.
Awesome video as usual. Great idea's. I always look forward to your words of wisdom.
The resistor wheelsets video is very interesting. Two possible problems come to mind:
1. Short term, depending on how thick the conductive paint is, do you find it adds friction to the turning of the axle? Do the wheels still turn freely with the paint on the axle?
2. Long term, how resistant is the paint to wear where the axle passes through the plastic bearings? Do you find the conductive paint wears away over time as the axles turn?
Thanks.
Clever idea 👍
Robin, A rake of coaches will need resistors at both ends, if you run them in both directions (if they're run into a terminus, the back of the train becomes the front) and not just a tail chaser. However, I can foresee a problem with that. If the rake is longer than the block section, then the block in advance and the block in the rear will both show occupied, but the block between them will show clear! You'll need resistors on one of the centre coaches in that long rake too.
Thanks I need to do this in future so most helpfull
have done this using 0805 10k on N gauge, old Lima Mk1 coaches - took a bit of fiddling with home made sensors to get them to reliably pick up the low current flow - way lower than a DCC locomotive just sitting there - have done one axle per coach on a few coaches, likely to do a second to have both outer axles - for freight stock one axle and then likely every other wagon.
make block overlaps enough one axle won't obscure a junctions, could do all but if stuff uncouples too much there are other problems.
once set up it works fine, the only issue is you now need to keep coach & wagon wheels clean, but a rake with a few should see a couple registering fine.
really good video actually showing how to do this.
if you have metal axles instead of plastic, stick the resistor at one end to bridge the plastic bush and its perfect.
if someone did these as a commercial product with a resistive axle it would be perfect, especially to replace plastic wheelsets on some stock :)
Very clever idea
Thanks Bruce. Can't claim it's an original idea though.
Hi Rob, great video as usual. Very fiddly job with my shakey hands, but I'm going to try it. You can use the stuff car accessory shops sell for fixing heated window elements as well. I wonder if you've had any problems with wheels derailing going through points, as the back to back distance now has a bit of a bump where the electric paint goes?
Please use caution: With each Resistor Wheelset the overall resistance of the trainset sinks. Most dangerous are long trains with short, two axis waggons. If you have too many of them, the resistance can drop so low that you get a short circuit. Better to calculate the trainset (R1 * R2 * R3 * ... * Rn) / ( R1 + R2 + R3 + ... + Rn) or measure the complete set on a powerless track with a multimeter.
I was just thinking about this myself, and I wrote a comment, but now thinking about it, if you have a long freight train you could probably do one resistor per stock unit.
So could probably get 16 plus coaches when doing and maybe end up with about 0.05A draw from the coaches......
That said, I'd like to see how that would work in real life and if it would affect it, especially with more trains running. :)
You only need resistors on the last wagon ( = brake van) in the rake (or if you're a modern image modeller [no brake vans], both the first and last wagon in the rake.). The only time it won't work is when there are some wagons in a siding, without a brake van or loco, but it's unlikely that you would need occupancy detection there.
Great thanks. Can you show what is involved at the other end, looks like an induction coil?
Hi Rob, I thought this was a good video and you explained the subject very well. I was surprised you needed to go to 5K resistors and so I took a look at what detection kits I was using. It looks like you are using MERG kit 50 which I think is an older design using current transformers. There is a cheaper alternative in MERG kit (PMK7) which uses the voltage drop across a diode to trigger the output. I have found the PMK (Pocket Money Kit) works very well with 10K resistors (ie very small current draw). Having said this I don't think the current draw is a concern with up to 8 resistors on a single block. On the PMK the output is opto-isolated and when connected between an input pin and ground on an Arduino input pin it works very well (with input pullup enabled on the Arduino input of course).
Great Video Rob! Makes me wonder if I should buy pre-built resistor wheelsets or just do it this way. Not all of my coaches have metal wheelsets, so I'm not sure how much cheaper it would be doing it this way, but any that do have metal wheelsets it would be significantly cheaper. I am running about 18 Volts so I might try 1-2k instead of 5k. I plan on doing automation and I m using your setup with Merg BOD's, an Arduino and a Sensor Shield. It works really well! Thanks
Hi Auxie! Firstly, thanks for becoming a Patron.
I looked at buying prefitted resistor wheels, but struggled to find good options.
Same here, I've got some coaches with plastic wheels so they'll either be left out or get upgrades.
Once you've got your sensors it's worth experimenting. I'd read 10k ohms everywhere, so fitted those only to find the resistance was too high for my sensors. Used 5k1 in the video, but will drop to 4k7 in future I think.
Keep an eye out for the monthly member only updates, stay in touch and let me know what you're up to 👍
Interesting video, but the problem this creates is that the panel will always show occupancy of two adjacent blocks because the loco will trigger the second block section on entering, whilst the goods van is still keeping the first section as occupied. Not sure how the full size system works, but I would presume that as a signal changes to red before the train has completely passed it, that the signal for the preceding block changes to a single yellow even though the remainder of the train hasn't fully cleared the section ?
Great video again Rob did you check the latest build instructions for the sensors?
Yeah, I made the required changes, but they're still not 10k sensitive. Potentially got it wrong some how. More loops required? I'm happy using the lower resistance. Will be fine once a few wagons are fitted up.
I will need to experiment also once i get around to sorting out a few changes to the layout.
Might be easier to clean the wheels before gluing on the resistors, so that there is no chance of knocking them off as the glue dries :-)
Also I've tried graphite based paint and didn't find it particularly good (maybe just the brand I was using), so now gone over to silver conductive paint. More expensive, but it is much better, easier to use, and gives a much better electrical connection.
Perhaps you could put some of the paint in a syringe and apply it to the wheels. Good video.
You made this look really easy with those Hornby metal tired wheels :).
I think I read this somewhere else, but how have you found the current draw with comparison to the whole layout?
If you have 2 resistors per coach 2x 5.1K would drop the resistance to 2, 550K per coach. If you have 8 coaches, that drops the resistance to about 319 ohms. I know it's not a lot, but that does make a current draw of about 0.05 Amp per rake at 15V DCC level, more if voltage is higher. Just curious how that would affect the layout as a whole.
Robin said that you only need them on the last coach in the rake. I say that you also need them on the first coach in the rake for when you're running the rake in reverse. Don't put them on the intermediate coaches as that may cause a voltage drop or short.
@@henrybest4057 I likely missed that. :) Thanks for bringing that up.
Great video, but pleease put the lid back onto the super glue, it was driving me crazy... :-)
Haha 😄 sorry for any mental trauma caused 😅
The glue works but then it doesn't work Especially if you paint the wheel sets
See you are using current sensors - maybe I m wrong but the only video I have seen from you is the opto ones
Its the one about £3 per sensor th-cam.com/video/DtYzP5RgcsA/w-d-xo.html
Hi Robin, I used IR/light sensors on my old layout, but have been using the MERG current sensors for a while now when it comes to occupancy detection (you can see these in action in the ABC braking video th-cam.com/video/y6MyOQrisIg/w-d-xo.html) and will be using these a lot on the new layout. The only other type of sensor I plan on using is an IR sensor that I've modified so that rather than relying on reflection it acts as an IR gate which the train passes through and breaks the beam. These will be used as stop sensors in the staging area. You'll see these in a future video.