I have two spots on the mainline where I have cylindrical magnet (three pairs) uncoupling but have decided (due to frequent undesired uncoupling with slack) to install electric operated Kadee 309s. I have reviewed older threads and the instructions (2012 and 2014 versions) but still have some questions. Sorry if I am a bit wordy.
a) On power supply, I am trying to figure out what to buy. The uncoupler works on DC, directly provided or converted AC (using the provided bridge rectifier to get it to DC). My older 2012 and the current (2014) download instructions both specify a target of 16v DC power to the coil. The 2012 instructions specify using either a 16v, 3A DC supply or a 16-18v, 3A AC supply. The newer 2014 instructions specify using either a 16v, minimum 1.5A DC supply or an 18v, minimum 1.5A AC supply. Note that both allow including an indicator bulb, which I do not plan to include. And note that the Kadee 166 power supply output is 18V AC, 2.2A.
Just for complete background, here is a 2006 comment from a Kadee rep on the 309 uncoupler. That is early on, so perhaps they would have a different input today.
"The new Kadee #309 electric uncoupler uses many of the same components as the older #307 version. The #309 mounts under the ties and is a lot easier to install than the #307 that required you to cut out the ties. You still have to recess it down into your layout base a few inches but since it can be attached to the bottom of the ties is very simple to install. After installation it is completely hinden from view.
Since the magnetic force is now farther away from the trip pin of the coupler we had to increase the voltage requirements to 18 to 20. It uses 4 field plates rather than two that increases the width of the magnetic field. We include a bridge rectifier and a capacitor so you can use AC or DC and retain the voltage level. In all of our testing the #309 worked just as good if not better than our #307. We had a demo #309 at the Philadelphia NMRA National Train Show that many were very impressed with. So far we have have no complaints about the #309."
My bias is to try to find a DC supply, skipping the need to use the bridge rectifier, keeping things simpler. I would add a fuse and a momentary pushbutton switch. I find sorting out a supply from the DigiKey or other places difficult as there can be an overwhelming number of power supplies and specs to sort out. So, I wonder if this Amazon 15v (adjustable voltage) DC supply would work? It looks like it is "light" by just 1 volt. I presume I gain a bit by leaving out the bulb? Or do I need a different supply? And, since rated at 45 watts (volt-amps), I hope that means that it can provide 3A at the max 15V if selected, not just at lower voltage selections.
https://www.amazon.com/Belker-Universal-Adapter-Household-Electronics/dp/B07J6RC43S/ref=sr_1_1_sspa?keywords=belkin+ac+dc+power+supply&qid=1564941223&s=electronics&smid=ASQ82QWPDLFS4&sr=1-1-spons&psc=1
b) Any recommendation on the momentary pushbutton on-panel switch? The Kadee 165 of course can do. I presume this is $4 for one switch, though the description says "4pkg"?? I would just as soon order an equvalent from someone like DigiKey (they are fast).
c) There is an "optional" capacitor (provided) to include in the input to the coil. It supposedly helps "boost or stabilize" the DC power. If not needed I would lean toward leaving it out. I can understand how it might stabilize the power, filling in for slight dips (variation). But how would it "boost" power, just by maintaining higher average power against any variation?
d) I will be installing in existing code 83 flextrack on cork roadbed and 5/8" plywood. I'm hoping that I can handle that ok, cutting out some track and then then with the repainting and ultimate ballasting making things look ok. I'm thinking I will not solder the rail joiners but rather add jumpers to the newly cut out track section, allowing for any maintenance needs.
Any comments are most appreciated.
Paul
Modeling HO with a transition era UP bent
1V less will probbaly be OK, if your trip pins are adjusted properly. Too low of course snags on things and causes derailments, but too high and it won't be within the magnetic field.
You won;t gain anything leaving the bulb out, it should be wired parallel to the electromagnet so all you gain by leaving it out is a slightly less current draw, if it is say a 50ma bulb then the thing will draw 50ma less without the bulb. Which is .05 amps, so practicaly nothing relative to the draw of the magnet itself.
That power supply should work, remember current is drawn by the load, not pushed into it by the power supply, so anything equal to or greater than the current requirement of the electromagnet is good. You could use a 15 volt 100 amp power supply, although such a thing would absolutely require fuse protection because 15 volts at 100 amps is enough to weld thick steel plates together. But absent a circuit fault - the electromagnet would work fine.
The capacitor is really only needed when using AC and the bridge rectifier. The resulting DC from just the bridge will have 60Hz pulses in it which will make the magnet buzz, the capacitor would smooth those out. Using a DC power supply means you don't really need it, but depending on how smooth and filtered the DC is from the power supply you are going to use, it wouldn't hurt to add it.
A suitable switch is where it gets tricky. It's not the current, or turning it on - the problem is when you let go of the button. A powerful electromagnet turning off intriduces a strong back EMF in the power wires, which will cause switch contacts to arc. With frequent use, they will ear out. One way to help prevent this is to add a diode across the coil of the electromagnet. A 1N5401, 3 amp 100V diode is good. You hook the + side of the diode to the - power wire and the - side of the diode to the + side of the power, after the switch, before the magnet. Yes, backwards - because if the diode was connected the 'right' way it would be a short. It may be hard to find a switch with a sufficient rating - switching DC is harder because there is no zero crossing point like there is with AC to help supress arcing. So a switch may be rated for 5 amps at 120VAC, but the DC raring might be 1 amp at 50 volts. Otherwise, any normally open momentary pushbutton, SPST, is all you need for this.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I have never used the 309, but I have used a few of the 307s.
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So... I will limit my answer to the switch type.
I have used a foot switch intended to operate power tools with 100% success with my 307s. It turned the power suppy on and off. I used a rotary switch to select which magnet was energized by the secondary voltage from the power supply.
A foot switch lets you use two hand to operated the layout.
-Kevin
Living the dream.
Thanks for the helpful info, guys.
A wrinkle I want to add...I'm unsure whether the Amazon power supply has a cord type I want to mess with. I have several 12v / 1A supplies that I use for lighting and they have nice twin wire rip cord type output cords that are easy to attach to a barrier strip. This 15v guy looks like a single cord, maybe an internal wire with a wrap around shield for the 2nd conductor? Not sure I want to mess with connecting the 2nd conductor since it's not an individual, stranded wire. Maybe I need to keep looking?
Or simply go with the Kadee AC supply and figure out where to put the rectifier bridge. I don't know where to mount a random electronic component(s) such as that (no circuit board) under the table.
And, darned if I can figure out whether Kadee 165 is 4 or 1 momentary switches.
https://tonystrains.com/product/kadee-165-momentary-push-button-quickie-switch-red
One of the adapters that comes with that poower supply is one to connect a pair of plain wires to - so you don't have to cut the end off the included wire and do anything with it, just connect the wires to your switch and the uncoupler to that wire adapter and then plug the power supply into it.
Kadee site says the #165 are 4 per package
https://www.kadee.com/all-products-c-81/165-quickie-switches-spst-red-normally-open-p-307.htm
I bought the exact same supply that Kadee sells by stock number from somewhere else and it was a lot cheaper.
Don't scrimp on the wiring. The magnets take a lot of current. Yes, you need a hefty supply for these things.
You might want to think about "planting" some tall grass between the rails. The magnet is strong enough to attract the metal axles of easy-running freight cars. The grass will hold the cars in place and not let them roll.
It takes an iron man to play with a toy iron horse.
Thanks, everyone. All the above info is great. This lets me move from an intention to Plan A.
I have one 309 on hand, plus fast blow glass fuse to include. I have ordered the Amazon (Belker) 15v DC / 3A supply which will arrive tomorrow. (Randy, good catch on the included wire type connector I did not appreciate.) So I can set the 1st one up this week, with a temporary SPST switch, used carefully to test.
I will order from Tony's the 2nd 309 plus Kadee momentary switches for finishing up at a later time.
Another great Forum assist!!
Well, time for an update.
On materials, I did order the Amazon 15v DC (adjustable voltage power supply. It is listed as 3A, but the spec sheet shows it as 2.2A output, 3A maximum. So I added a 2.5A fuse. Note that the 2012 #309 instruction sheet specified a 3A supply, but the 2014 sheet updated that to 1.5A (I confirmed that issue with Kadee). I used the Kadee #165 momentary SPST switches, and their tech guy said that they are reliable enough (re: potential sticking) so I did not include indicator lights to avoid overheating due to excessive time turned on.
On installation, I had some fun releasing the existing flex track. The latex on cork roadbed released easily by sliding a putty knife. I had to cut the track at one spot to stay in the straight section so I purchased the Dremel flex attachment just to be able to easily cut vertically just at those two rails. At the turnout, I did not solder the joiners and had to release it (very lightly latex tacked) to grab the cylinder magnets I had placed within. No problem. At the right side of each track I had to unsolder (painted) rail joiners. That was interesting to apply enough heat to slide the joiners (tight but small N80 ones I prefer) to one side. I decided to just fix up the messy (some solder, etc) rail ends on the existing track on the right, but put new track pieces for the coupler track sections, making the rail joiner make-up easy for re-installing by sliding the joiner from the new piece onto the old rail. In hindsight, I should have just cut the uncoupler tracks (shorter) on the right side also and allowed additional rail joints with new joiners, much easier.
I then followed the #309 instructions to remove some roadbed, cut the rectangular holes, and wire things up. I used 20AWG as suggested. Small 20 AWG pieces fit nicely into one of the many wallwart output cord connectors, as Randy pointed out. I used a barrier strip to make the wiring easy as possible under the table.
I have one uncoupler in as of now, short of cosmetic things like roadbed fix-up, track paint, plus feeders to these unsoldered track sections, etc. I tried it today (two cars, hand operated) and it works fine. Installing the second one should be quick.
So, I will be liking these much better than the unwanted mainline uncouplings that I was getting (due to slack) with the cylinder magnet pairs. I still have some of those on sidings and intend to continue to use them. I do not do any "operating", at least so far. I mostly work on projects, run a train occasionally for myself, but most running is when the grandkids are here.
That's my followup report. Thanks for all the earlier comments! And if interested in alternate approaches to "always active" uncoupler types, check out a couple of ideas that folks refer to in this past weekend's (Aug 9-11, 2019) Weekend Photo Fun.
Uncouplers Prep (2) by Paul Ahrens, on Flickr
Uncouplers2 (2) by Paul Ahrens, on Flickr
Uncouplers3 (2) by Paul Ahrens, on Flickr
Uncouplers4 (2) by Paul Ahrens, on Flickr
Uncouplers5 (2) by Paul Ahrens, on Flickr
Uncouplers6 (2) by Paul Ahrens, on Flickr
Uncouplers7 (2) by Paul Ahrens, on Flickr
Thanks for the update.
I look forward to the next installment. This might be something I use on the next layout.