Broadway Limited T1 Speaker Transplant

[Zack L-J]

I do rather like CodyO's solution, however I was thinking of sticking to the one speaker in order to have some room for a keep alive. I hate the way the speaker stutters on anything but absolutely perfect track.

[Mike C]

The Scale Sound Systems link to their N scale speakers says "coming soon." 

If it were me, I'd copy what CodyO did.  The speakers can be ordered from sbs4dcc.com

John C.

  I was thinking that the smallest HO speaker may fit in that tender it's 9x15x25 .   Mike

[jdcolombo]

I do rather like CodyO's solution, however I was thinking of sticking to the one speaker in order to have some room for a keep alive. I hate the way the speaker stutters on anything but absolutely perfect track.

My original post used a single 13x18mm speaker and it sounded very good, IMHO.  But I don't think you'd have room for a commercial keep alive even with that.  You'd have to measure the available space; I've used the TCS KA-1 in my N-scale Berks and Mikes alongside an ESU LokSound 5 micro (wired) with a 13x18 speaker, but the decoder layout in the T-1 might prohibit doing this.  If you were willing to "roll your own" on a keep alive, there probably would be room for 3-4 220uf 20v tantalum polymer caps.  It wouldn't be a real keep alive in the sense of keeping the motor running over dirty track, but it might fix sound dropouts. 

John C.

[Zack L-J]

Thanks John. I was planning on running my own keep alive with smallish supercaps, but I also thought about disassembling a KA1/2 in order to relocate the capacitors hither and yon where they fit. There is a *lot* of room in this tender but you’re right about the decoder being obnoxiously in the way.

You mention 220 tantalums which is funny because that’s exactly what I have in my superliners for keep alive.

[peteski]

Thanks John. I was planning on running my own keep alive with smallish supercaps, but I also thought about disassembling a KA1/2 in order to relocate the capacitors hither and yon where they fit. There is a *lot* of room in this tender but you’re right about the decoder being obnoxiously in the way.

Zack, I'm curious as to what those "smallish supercaps" are?  Like their capacitance, max.  voltage, size?

[Zack L-J]

Well there are several options. One tempting one is a lithium carbon capacitor, which is sort of a hybrid of a battery and a capacitor. 7 farads in a 6.3x11mm package with a 2.5 to 4.2v operating range for a ANGA POW ZCC705S0ME11RR(look it even has RR at the end, it’s practically meant for trains!) for example. I can quickly whip up a little PCB with a boost converter and charge/discharge circuit.

Or for more traditional supercaps there is a huge variety. The 5.6v rated 7x10mm 4 farad Vishal Beyschlag(just rolls off the tongue) MAL219691104E3, for example. It’s got a significant internal resistance(10 Ohms) so it should have a circuit with it too, but less complex than the above. It’s also bloody expensive at $11.30 apiece, unlike the $1 anga above.

Another normal one is the 6.3x14mm 3v 1f $1.85 240mOhm Kyocera AVX SCQ12E105PRB. Seems like a nice all rounder and with the low resistance it likely doesn’t even need a circuit to go with it, though fitting 4 or 5 of these in that cramped tender might be difficult.

When I start actually assembling and testing I’ll probably make a dedicated thread for this.

[peteski]

Ah ok, thanks! I'm familiar with most of those choices.  But designing and manufacturing a buck DC/DC converter (which will not only charge the battery at a lower voltage, then convert the low voltage to something usable on a decoder) is beyond the abilities of most model railroaders.

As for lithium based storage cells, knowing all the bad reputation they have (similar to tantalum caps) I would not want to put it in a expensive model locomotive.

Sounds like you will basically design your own version of ESU PowerPack circuit (which uses a standard 1F 2.7V GoldCap).  I would be interested in seeing a separate thread on that.  Always willing to learn new tricks.

[Zack L-J]

Yeah, designing a power supply is definitely too much for most. Of course if I did design a power supply PCB, I’d definitely share it with the community at large. Both the files and selling assembled ones. The lithium hybrid cells i am referring to can be controlled with a single chip, and they’re far less volatile than actual lithium ion batteries. Still it is a very real consideration. You cannot run them without proper protection circuits in place.