Ed - Thanks for the tip on the ESU units. I wasn't aware of them. Having had a look, I have ordered two, as I think they'll do what I want just fine.
Charles - good looking interior!
Cheers,
Bob
Wow, this forum has been very educational...I never knew about different bridge rectifiers having different speeds!
I'm not sure if this helps but if you want a keep alive effect, simply wiring a 360+ uf capacitor parallel to the LEDs should work. In particular, after the rectifier, and before the resistors that limit the brightness of the LEDs.
I've seen some people (mel?) adding a reed switch into their lighting circuit, so they can turn the lights inside the car on and off via a magnet.
Obviously, adding a function-only decoder(with keep alive) is a easy solution, but for most people, spending that much money on a per car basis is a bit much. If you are going to though, might as well go all out and get a Soundtraxx SoundCar decoder
I usually like to hide the capacitor in the restroom stalls, where you can't see it, like in this Branchline Heavyweight car:
Hope this helps!
Charles
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Modeling the PRR & NYC in HO
Youtube Channel: www.youtube.com/@trainman440
Instagram (where I share projects!): https://www.instagram.com/trainman440
FowlmereRRI am now thinking of fitting a function-only decoder with keep-alive in each car
May I offer a suggestion?
Take a look at the ESU lighting kits.
http://www.esu.eu/en/products/interior-lighting-sets/
I bought several of these and have experimented with them. I don't know what £ UK cost would be but in US these were under $20 each and they have a built in decoder, you can easily add a keep alive cap and they have many lighting effect options. They even come with red LED for marker lamps which you can disable if not needed.
I have programmed in the flicker effect to imitate a bad fluorescent ballast. Neat effect. There is a golden color or a fluorescent color available.
The English instruction sheet can be found here:
http://www.esu.eu/en/downloads/instruction-manuals/interiour-lighting-sets/
Good Luck, Ed
Randy - I think you are on the money with the speed of the diodes.
I got the 'scope on the DC side of the circuit this morning (I am in UK, in case you wondered about timing!) and it does look very spikey. The buzzing resonance is also much less apparent when the board is not mounted in the coach, but you can actually feel the thing vibrating, and you can damp the vibrations with your hand by holding the board in different ways. Very strange effect!
I could, as you say, try swapping them for fast recovery diodes, or fit a fast bridge rectifier, but as there is no way of controlling the lighting, I am now thinking of fitting a function-only decoder with keep-alive in each car (I only have the two) so I can switch the lighting by DCC. Just a case of finding the best decoder to use, and actually finding somebody who has them in stock - things are getting hard to get here at the moment.
Anyway, thanks again for all input.
Yeah, the factory board already has a bridge rectifier, the 4 diodes along the edge next to where the switch would be for rail/overhead selection.
Diodes have a switching speed, they don't work instantly, so a diode that may be fine to prevent reverse power input with DC, or work as a rectifier for 60Hz AC in a power supply may not be up to the task for the much higher frequency of DCC, and the 'leakage' might be enough to make the regulator sing a bit. Depends on the diodes used. Replacing them with faster ones, or a fast bridge. None of the data sheets on the DB107 I found mention reverse recovery time, which is the parameter of interest for high speed switching. The IN4148 diode is often used for rectifying DCC, but they are only rated for a max of 450mA. Which is probbaly fine for a circuit that runs 4-5 white LEDs.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Mel - Don't you think that the four diodes, D3-6, in the pic are likely to be a bridge rectifier? They are marked as "M4" which I think may signify a 1N4004 device. Later today, or tomorrow morning, I'll get my PC oscilloscope working and look at the waveforms on the DC side of the board. My guess is it will look very spikey, hence inducing a resonance somewhere.
I'll also try to email Con-Cor about this, but they don't list this model anymore, so they may not be able to comment.
Thanks for all the suggestions, friends - much appreciated. Stay safe.
RR_Mel If as you say it works OK on DC the simplest fix is using a bridge rectifier such as DB107. I use the DB107s for many things and keep a good supply on hand, they are cheap off eBay. https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=db107+rectifier&_sacat=0&LH_TitleDesc=0&LH_PrefLoc=1&_sop=15&_osacat=0&_odkw=db107&rt=nc Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
Where would one install this bridge rectifier on the board?
Gary
Hi, Bob
The photos look fine.
That is the same board I have in my Con-Cor MP54s. Mine do not make any noise on DCC. The connection for "ant" is supposed to read "pant" for pantograph and the other solder points are for headlight LEDs and a switch for same.
About the only component I see on there that might make noise would be the V1 voltage regulator. I wonder if Con-Cor has any help if you email them? Could be a common problem with some boards?
Thanks for the input, all.
First off, on DC all is quiet, as expected. It only produces noise on a DCC feed. It IS designed to work with DCC, according to the Con-Cor documentation.
I've tried to add some pics here - I've had mixed success with this in the past so if you don't see anything first try, let me know!
Maybe all this will help?
Thanks anyway,
mbinsewiOK Bob, thanks. A couple of members in here, Mel, and Ed, (gmpullman) I think are the resident experts with passenger car interiors
Expert? Hardly, just been around long enough to have run into similar problems.
I haven't experienced the Con-Cor circuit but I did have the same problem with the older, first version of the Walthers add-in lighting kits. These had incandescent lamps, four diodes, a capacitor and (either) a transistor or voltage regulator mounted to a heat sink. They were noisy on DCC.
Come to think of it, I DO have some Con-Cor PRR MP54 cars with installed lighting but they are not at all "noisy".
These Walthers versions were labeled as "DC only" but I had already installed several in some of my cars and they did emit a high frequency whine when on DCC track.
I eventually gutted the wiring and using the same light bar, added LED lighting using a common circuit for LED "keep-alive" shown below.
DCC_light2 by Edmund, on Flickr
Sleeper_lights-crop by Edmund, on Flickr
I'll see if I can dig up any specifics on the Con-Cor design.
Can you test them on a DC circuit? All you need is a pair of wires and a 12 foot DC supply. Even a 9 volt battery will do. Just connect power to the wheels with clipleads or even by touching the wires to the wheels by hand.
If you get no noise with DC, you could probably fix it for DCC by adding a rectifier bridge on the power input inside the car. It sounds to me like some circuit component is designed for DC only. The rectifier should fix that.
It takes an iron man to play with a toy iron horse.
OK Bob, thanks. A couple of members in here, Mel, and Ed, (gmpullman) I think are the resident experts with passenger car interiors
I'll back off and let them help you. The only cars I have with interior lighting are from Rapido.
The extra info you gave will all help.
Mike.
My You Tube
Mike - these were bought direct from Con-Cor, and are a shortened 65' coach - they are LED. There is a long narrow circuit board which plugs onto four tall power pins, two at each end of the coach interior. The enclosed "instruction sheet" merely says that you can expect varying brightness on a DC layout, and constant brightness on DCC. There is no on/off facility, though the circuit board seems to have space for some additional components that may provide this in some versions.
Are these bulbs? I didn't think Con-Cor cars came with interior lighting. I know that lighting kits can be bought.
Maybe some more info on the cars you bought. Is this an Ebay purchase? Hobby shop?
Maybe it's a voltage thing with the DCC.
I have two Con-Cor HO Heavyweight passenger cars, one Coach and one Combine, that came with interior lighting units. I bought these a couple of years ago, but have only just got round to putting them on a live DCC track. Although the lighting units work fine (a rather pleasing dull yellow glow rather than a garish white), they produce a nasty whining buzzing sound which is unacceptably loud.
If I remove the car body shell, and touch the circuit board, I can feel a mechanical vibration that, with gentle pressure, can be damped a bit to reduce the noise.
Has anybody else come across this issue, and if so, do you have any suggestions on how to silence it?
Thanks, Bob.