Shinkansen DCC Interior lighting with Flicker-Free feature

[Melandir]

Yes, but most controllers can output more. The Kato one for example can produce 16V in the red. The caps can be used on less, but not more. You can literally blow your shell to pieces with a blown cap. I would say you should use a 24-25V cap for N scale to be sure. Actually this is the NMRA recommendation too. :-)

 

I actually use a 16V cap with a DCC voltage of 18Vac when I use the train on club layout, but I have the rectifier and the led strip that bring down the voltage to the limit.....It was an early design mistake, now I use too 25V caps to be safe

 

At home it's not a problem because I use 14V as max voltage

[HantuBlauLOL]

Now i got a problem.

 

Rectifier 8A 40V seems to nowhere to be found nearby, any alternatives? I'm thinking about 4 diodes arranged in rectangle, could this works? Also what type of diodes would I need?

 

LM334M/X too, only LM339 available. Could this works? How?

[kvp]

You don't really need 8A, just use standard 1-2A diodes or a single chip rectifier made out of similar diodes. But you _must_ use the LM334M or alternatively the LM134. The LM339 is a quad comparator and is a completly different chip for a completly different circuit.

[HantuBlauLOL]

What is the voltage for diodes? 12V?

 

Also how to use the LM134 on this circuit?

[kvp]

The diodes and the cap should be at least 24V or more. See the circuit diagram i posted above. The LM134 is just a replacement part for the LM334M, so you can connect it as it were an LM334M. Just be careful when you solder not to burn the chip with too much heat.

[HantuBlauLOL]

Heck, even the LM134 isn't available here..

 

However the shop guy suggest me to use L78XX instead, would it works?

[kvp]

No. That's a voltage regulator, while the LM134 is a current regulator. The 78xx series would just convert most of your electricity into heat, so your capacitor would last less than a second and you could also melt your trains at the same time. Not to mention they have a rather high starting voltage (7 volts for a 7805, together with the diodes that is 8.4V minimum), so your leds won't turn on until you reach near terminal velocity with the train. I suggest you to find a real electronics shop, instead of a hobby one or order the chips online. Just be careful that the LM134 family comes in various packages and you need a small one that can actually fit into a train.

 

Actually these small circuits one can find on the net are pretty carefully engineered and changing anything on them would often break their functionality. The simplicity of the circuit itself in this case doesn't mean it's a simple circuit. You need carefully selected parts (especially for the leds) to work. Getting normal off the shelf leds in a hobby shop would result in an uneven brightness or only one or two leds turning on and the rest remaining dark. So unless one can obtain a specially matched set of low current leds, an LM134 in a small package, a small smd bridge and an 1% precision tuning resistor it won't really work.

 

ps: Don't be surprised that it's hard to get the parts. I can't seem to find 15.6V / 1 watt zener diodes at the moment in the whole city. Sometimes even the big japanese manufacturers have to delay or cancel a product if they can't get everything they need to build it.

[HantuBlauLOL]

My local shop is an electronic sparepart shop.. But even they don't have a led strip, I just get the elco and resistor from there

 

Yesterday I went to another shop, this one is electronic robotic shop, got the led strip and diodes here (1N4002 type)..

 

Still missing the LM334/134 though, it looks like an Egyptian treasure to find..

[kvp]

 

got the led strip 

Is it an integrated one with resistors already added? Because if it is, that won't work. The idea with the lm334 is to get rid of the many small resistors that just burn up power, so the leds can run longer from the small capactor by limiting their current actively at a single point.

[HantuBlauLOL]

No resistors, they are wired in parallel 12V..

 

But.. they aren't bright even on 10V..

 

It contains 60 leds, 4.8W, or approximately 0.4A per meter.

Edited January 16, 2015 by HantuBlauLOL

[kvp]

The strip must contain some form of current limiting, so if you are running them without a tesistor, then they don't need the chip either, so just add the diode bridge and capacitor and you are done.

[HantuBlauLOL]

Eh? But it still changes its light intensity when I change the input voltage..

[kvp]

That means it has small smd resistors somewhere. Either separately or inside the led packages. The circuit you were trying to recreate requires normal leds, which would burn out instatnly if you connect them directly without current limiting. Also, the circuit we are talking about keeps the light level constant regardless of voltage.

[HantuBlauLOL]

I can't see it anywhere.. It must be inside the led

 

Separate SMD led pieces are also hard to find here. I'm thinking about cutting standard Led's lens to half, leaving the diodes only.

[HantuBlauLOL]

little googling gets me this:

 

http://www.awrr.com/ConstantLighting.html

http://www.awrr.com/lighting.html

 

i wonder how those circuit's current limiting works? i'd ignore the battery equipped one anyway

 

especially this one:

[kvp]

Essentially the diodes drop the voltage for the motor, so it doesn't start to turn before the leds are fully lit. They also act as a constant voltage source for the leds. The current limiting is done by the resistance of the motor windings, so in case of a stall or commutator short, the leds will burn out. Also if the motor has a low resistance, they will burn out during normal use too.

 

As the site say:

 

I have not personally tried every variation of diode and LED.

If you're experiencing a too-dim or too-bright LED, Email me
with the particulars of your LED and we'll try to find a solution.

So the leds could get too little or too much current and the combination of motor, controller, type of the leds and the amount of dust on the track will vary the intensity of the leds. The circuit is actually only good for low voltage bulbs, which are self limiting or you can drop more voltage and add resistors in series with the leds. The side effect is that you will loose the top speed range of your train. (which is fine as long as it's not a shinkansen) Also each led type needs a different voltage to turn on. This means you need more voltage and a different number of diodes for a white led than for a red led.

[HantuBlauLOL]

So its for MC only?

 

How about the #3 circuit (alternate deluxe lighting) on this site?

http://www.awrr.com/lighting.html

[kvp]

All of the circuits on that page are for blubs only. The problem with bulbs is that they need lots of current and generate lots of heat. So i would only use them with larger scales, like H0. Not to mention many circuits use bulbs painted black as ballast (a self regulating current source), so they only generate heat. The solid state circuit earlier in this thread is meant to replace all these blubs with a solid state chip circuit. Of course you can use bulbs, just be ready that some of your cars could melt from the heat and you will have to keep replacing the bulbs fairly often. (also the lm317 has the * that a clip on heatsink might be required, so that's clearly for larger than H0 scale and preferably non plastic rolling stock) In short, my suggestion would be to skip that website unless you want to see molten cars.

[Melandir]

I have started working with this second light system, the first thing I found is that it's impossible to install a normal capacitor

 

Tantalum looks the only way to go if we want to install a capacitor in a japanese carriage, but tantalum SMD capacitor rated 25V can only reach 100uF capacity

 

If I want the 200uF capacity I need to go down to 16V

 

 

 

Edited February 1, 2015 by Melandir

[cteno4]

what about using two 100uf smd tantalum in parallel? the D case ones are pretty tiny. only issue is cost. ive found them as low as 30 cents each on ebay though for a batch of 50.

 

jeff

[Melandir]

That will work Jeff se the below picture

 

I have found an offer on Aliexpress, 50X100uF tantalum 25V for $17.10 with free shipping

I think I'll get 100 of them just to be safe but with 2 each they will be gone in an earthbreath

 

I'll first test with one capacitor just to understand how long it will last, japanese carriages are smaller than european ones and I estimate 4 leds for normal and up to 6 leds for shinkansen ones, but I need to start playing to know for sure

 

[cteno4]

Yeah about the same price as ebay (and many times the same supplier!)

 

Looks good. Couple of bits of cards rock around it to hide them.

 

The other day I was at the craft store and ran across floral wire in a few different gauges. It looks like just galvanized, straightened wire and maybe perfect for these, fraction the cost of brass stock. I have to see about the conductance and how well it solders.

 

I just have not had the time to work on this stuff, hope next month will be mellow.

 

Jeff

[kvp]

Floral wire should be galvanised iron and not brass or copper. (it's great as a guide wire for the Tomytec bus system) I mostly use 0.5 mm solid core copper wire with the plastic insulation stripped off. It's not as springy as brass, but when no spring action is needed, it works fine and it's very cheap. Once soldered together the whole circuit can be painted over with insulating acrylic paint to hide it. (just don't cover the leds and the pickup contacts)

[Melandir]

I have found this auction on ebay for brass wire (half-hard) that could be helpful, price looks ok to me

 

http://www.ebay.it/itm/321354972822?var=510249765792&ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

[E6系]

That will work Jeff se the below picture

 

I have found an offer on Aliexpress, 50X100uF tantalum 25V for $17.10 with free shipping

I think I'll get 100 of them just to be safe but with 2 each they will be gone in an earthbreath

 

I'll first test with one capacitor just to understand how long it will last, japanese carriages are smaller than european ones and I estimate 4 leds for normal and up to 6 leds for shinkansen ones, but I need to start playing to know for sure

 

IMG_20150201_214201.jpg

Hello Melandir,

 

Could you install these between sub-floor parts?