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Post by corsair on Apr 17, 2017 12:45:26 GMT -5
One of the most interesting things for me that changed in the hobby after a long hiatus is an interest in batteries and radio control. It's a nice idea that the locomotive is self contained power and the tracks are just tracks. Practically speaking, I want to build a switching layout with lots of frogs and tiny motive power that gets sensitive about dirty track. Being new in the hobby I have no existing infrastructure and can start from scratch.
I'm planning on giving myself a real challenge and shoving all the components in an SW1. The off the shelf parts are too big, but companies like Adafruit make even smaller parts. If you can accept the locomotive either running OR charging, the largest circuit board by far can be jettisoned. The smallest 150mAh batteries are an inch long and only .14" thick, and the charging circuitry is tiny. You just need a switch to go between Run, Charge and Off.
So has anyone here used radio control? What did you think? Any comment on real world run times?
Also, what is the minimum voltage input for a decoder? I have to step up the battery voltage anyway, but circuits come in 5, 9 or 12V. A switcher is unlikely to need more than 9V at the motor, can the decoder operate there? Or even 5V?
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EMDX6043
Chairman
Future ex-modeler
Posts: 837
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Post by EMDX6043 on Apr 17, 2017 20:39:18 GMT -5
You'll more than likely want 12v for the decoder, but how will you control it since the digital commands are sent through the rails?
(I might just be having a brain fart...)
EDIT: Found info about the transmitters and receivers. Neat stuff!
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Post by analogbeatmaker on Apr 18, 2017 2:13:49 GMT -5
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Post by corsair on Apr 18, 2017 10:47:24 GMT -5
Wow! That's really cool! I'm especially interested in the run time he is expecting. He figures a few hours out of a single cell 700mAh battery! Beautiful work too. Here in Golden we see those BNSF SD40-2s everyday working the Coors branch. Every once in a while I get a treat and one shows up in Cascade Green I stopped by an R/C shop yesterday to pick their brains about batteries. They're used to the same 12V as us, but at much higher amperage. They look at the voltage step ups as a waste of power and rely on multicell batteries to get to 7.4V or 11.1V as a base. I think you still use a voltage converter to stabilize the power, but you minimize loss with a small delta. That contrasts the SD40-2 in the link that uses 3.7V and converts it up to 12V. The core inefficiency seems to be stepping up to 12V just to have the decoder knock it back down for the motor and LEDs. That's why I'm curious if the decoder will operate at 5 or 9V. As far as the batteries themselves, they roughly split into R/C and microelectronics camps. The former offer prebuilt multicells with a second plug for balancing and charging. They do not include any over or under voltage protection on board. The type of lipo from Adafruit contains its own protective circuits, but only comes in single cells. Not sure which route is best. Another consideration, batteries can get really hot when charged. I have some concern about packing the switcher too tight and cooking the shell when it charges. I built the body to have easy access under the hood. The wise route may be to charge the battery externally and treat it like an R/C car on rails.
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EMDX6043
Chairman
Future ex-modeler
Posts: 837
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Post by EMDX6043 on Apr 19, 2017 6:41:02 GMT -5
It may be possible to house the batteries in a trailing "dummy" unit and have a jumper between them. Those Miniatronics connectors are rated for 1 amp.
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Post by corsair on Apr 19, 2017 9:33:02 GMT -5
It may be possible to house the batteries in a trailing "dummy" unit and have a jumper between them. Those Miniatronics connectors are rated for 1 amp. It's very possible. Rolling stock gets used too, like a box car, so you could theoretically swap them out to 'refuel.' Something like a BN style fuel tanker would be really cool! I saw installs with paired locos too, just as you say. I have considered building a slug to house more gear, but it seems like overkill for now. I don't have a layout and the space I have to work with is 17" x 94." (The real reason I bought the SW1 to begin with) Its a very low bar where external charging and modest run times are perfectly fine. After talking to the RC shop guy, I kind of want to skip onboard charging and use the platform to experiment with batteries. Single cell vs multicell for example. Once a learn a little more I have a GP35 on the bench that could be built to include charging and more capacity for a 'real' layout.
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Post by lajmdlr on Jun 26, 2017 13:31:36 GMT -5
DCC can be sent wireless now so it doesn't have to go JUST thru the rails. Everything can be sent via radio these days. There are several systems that can be found thru Google.
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Post by corsair on Jul 3, 2017 10:00:17 GMT -5
DCC can be sent wireless now so it doesn't have to go JUST thru the rails. Everything can be sent via radio these days. There are several systems that can be found thru Google. lajmdlr, I think that's a really good point. Sending the signal through the air rather than the rails is a separate issue from powering the motor. RF receivers are tiny and cheap. NCE makes decoders with radio receivers already for a negligible price increase. Sound installs have a price premium as even prebuilt packages have 2 boards back to back. Sooner or later, a sound manufacturer will produce something too if NCE sells enough.
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Post by lajmdlr on Jul 11, 2017 22:23:57 GMT -5
Biggest space consumer for dead rail is the batteries. To put those in a small diesel requires replacing the motor & trucks w/ powered trucks like those made by NWSL (Stanton Drive). It can be put in a trailing car but my layout is all switching so don't want the same car always following my diesel. Once that's done then the combo motor control/sound chips & speaker can be put in the shell. Both LokSound & Soundtraxx make small chips to do both.
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Post by corsair on Jul 13, 2017 10:18:50 GMT -5
Biggest space consumer for dead rail is the batteries. To put those in a small diesel requires replacing the motor & trucks w/ powered trucks like those made by NWSL (Stanton Drive). It can be put in a trailing car but my layout is all switching so don't want the same car always following my diesel. Once that's done then the combo motor control/sound chips & speaker can be put in the shell. Both LokSound & Soundtraxx make small chips to do both. The batteries suck up space, but at least have the virtue of being heavy. Having an SW1 here with a newly installed set of Stanton drives, a new problem is rearing its head. Weight. The "empty" switcher is a real featherweight. Decoders, speakers and charging circuits don't weigh very much. They also eat up all the space for ballast. IMO, the real compromise at the moment is onboard charging. The only off the shelf solution is the Stanton BPS, which is huge. Bigger than the battery in most of the arrangements I've tried mocking up. There are other power path management boards for Arduinos, but they tend to be the wrong shape. Not long and skinny like you would want. At least for me, that's where I'm stuck. There is a functional compromise no matter how you put it together. Charging from the main while running is nice, because you have infinite range. In a small model, that currently means skipping ballast and getting a locomotive that doesn't pull much. There are other, more space efficient ways to charge the battery when the decoder is powered down.
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