BCD Switch Control Circuit

[cteno4]

There is a great little circuit if you want to control your unitrak or finetrak points via spdt buttons in a control panel (ie two micro push buttons, one on each direction of a layout diagram). this very cool little design called the BCD circuit was created by George Stillwell. he will email you a pdf of the design if you want it (he is not putting it on the web yet as he wants to publish it and some places will not publish if its been posted on the web). yell and i can put you in touch with him if you are interested. if you do get it from him please dont pass it around and follow his wishes as he did this on his own and its nice of him to share it and his time with us.

 

this circuit does a capacitor discharge pulse (better for the coil) that you can then wire to momentary push buttons or spdt switches. the capacitor discarge is probably the best way to fire coils like this as its a very good momenary pulse that wont burn out the coil (if a controller hangs some or you use momentary dpdt switches alone and push too long) and is just what the coil wants to see to power it. also has options for adding led indicators to show current switch direction, do ladders, and also do default switch settings when you power up. You can create a circuit that will switch a ladder of points to go to one particular track in your yard!

 

i hope to build a few of these and experiment some this summer with these. very simple circuit that anyone with just a tad of electronics could assemble. he even has a design that you just wire up on a small screw terminal strip so no soldering or pc board, etc. someone on the ttrak board just offered to make some pc boards maybe for the circuit as well so it would be even easier to build these. I have looked at a few of these kinds of circuits in the past and most were overly complicated and many very specific in its use. BCD is nice in that its pretty simple, modular and flexible.

 

cheers,

 

jeff

 

uodate: George Stillwell passed away a few years back so I’ve decided to make the files public, you will find them in a post further down this topic. jeff

[Tenorikuma]

I would be interested in such a circuit.

[alpineaustralia]

me too

[scott]

I'm clueless about electronics, but I'd be interested--sounds like a better solution for switch control for our layout.

[cteno4]

anyone interested pm me and ill put you in touch with the guy to get all the info from him. very nice chap.

 

cheers

 

jeff

[quinntopia]

I'm with Jeff.  I got the plan from Mr Stillwell about a year ago, and given various delays and a lot of back and forth questions with Mr Stilwell, I got it to work, and its fantastic.  Huge improvement over the blue switches!

[gavino200]

I know this is an old thread, but I'm wondering if anyone is still using this point control system?

 

Can anyone give me a link to Mr.Stillwell's website or his email address?

 

Also, I'd love to hear about any other point control systems out there, or designs for making one. There's a nifty looking one in the gallery section of this forum but I can't find an associated thread.

 

http://www.jnsforum.com/community/gallery/image/1035-ver1-3-a/

 

Thanks

 

Gavin

Edited May 22, 2014 by gavino200

[cteno4]

Gavin,

 

It's a super simple but effective and versatile. Ill pm you his email address

 

Jeff

[gavino200]

Thanks Jeff. Looking forward to getting that.

 

Gavin

[kvp]

If this circuit is not top secret, is there a way to know how it works?

Edited May 25, 2014 by kvp

[inobu]

The OP was stating the capibilities that the basic BCD can provide. After seeing the basic circuitry I could see its potential

and applied it to a custom case. The first level control logic is in how you flip the switches as this box would provide.

Second level can be applied by transitors and relays. It is unrealistic to expect logic control from a capacitor and resistor.

 

 

The picture above is an example of how the simple circuit can be used or intergrated into a robust design.  

Edited May 26, 2014 by inobu

[hucomp]

Can you give me some details about what parts are used in the LED diagram you attached to your post?  (My source for electronic parts is several miles away.) This is exactly what I need to continue building my new layout and yours is the first diagram I have found about it. Do you also have information about operating several switches from the 1 capacitor, which I understand can be done?

Thanks.

[cteno4]

Hucomp,

 

Pm me and I can put you in touch with George Stilwell and he can email you PDFs with all the details for doing leds, reset circuits and ladders.

 

Cheers,

 

Jeff

[HantuBlauLOL]

What is the function of cap and inductor there? Slower blade movement perhaps?

[cteno4]

actually kato and tomix coils have impedance that dont need that large a cap to get a good snap w/o overloading them. 

 

anyone interested pm me and ill get you ray stilwells contact info to get his pdfs. He has not wanted to publish all the pdfs yet so does not want them posted online and just asks folks to keep them for their own use and have folks contact him if they want the files. 

 

jeff

Edited January 22, 2015 by cteno4

[hucomp]

The inductor is the switch coil itself, while the 2200 uF capacitor in series provides the charge/discharge current. The leds are the 20mA type and the resistors should be 1k ohm for the 12V DC japanese turnouts require.

 

There should be 1 capacitor per turnout. If you connect more, the circuit will sometimes misfire. The classic BCD circuits require only one for all turnouts, but they have a recharging delay and also misfire when more than one switch is thrown or when the operator is too fast. On the other hand the series version is self limiting and can switch all turnouts at the same time and doesn't have a recharge time. Essentially you drive the coil with constant DC and the capacitor limits the time the current flows. You can also connect more than one coil/cap pair to a single switch.

Have you used the Power-On-Reset system with the BCD setup and is it worth the effort? It looks confusing.

Thanks.

[cteno4]

Hucomp,

 

Check out ray's PDF, he has a nice way I'd doing this power reset that is totally automatic. Makes for a little more wiring, but will do the trick nicely!

 

Cheers,

 

Jeff

[cteno4]

By the time you drill holes in theirs, mount leds and wore them in it would have been much faster, easier and cheaper to roll your own!

 

Jeff

[mrp]

If was going to start drilling holes, I reckon I’d start with blank piece of anodized aluminium rather than an over-priced ¥8,000 Cosmic panel.  Did you check out their web site?  You can even invest in a desktop model for ¥12,000.  Ouch!

[cteno4]

Yeah at a buck a circuit and 5 minutes to wire, it's a no brainer to roll your own.

 

Jeff

[cteno4]

Kiwimagic,

 

Pm me and I'll get you all the docs

 

Jeff

[cteno4]

Sadly I just learned George Ray Stillwell who popularized the BCD capacitor discharge point throw circuit passed away in May. I had feared this when he stopped responding to emails a while back. He was a very good egg and very helpful to folks providing his BCD circuit plans and answering gobs of questions of folks. He had patience with newbies to electronics and generous with his time. I enjoyed corresponding with him and bouncing ideas around. Ill miss him.

 

jeff

[cteno4]

So George has been gone for about 6 years now and recently some folks asked about the circuit. I had tried to reach George’s family after he passed to see about his BCD documents but no luck. I’ve decided it’s probably best to just post his documents now. He was waiting to try to publish the circuit in one of the train magazines but he never got his manuscript finished to publish. He had not wanted the documents published on the web as this could easily stop print publishing of it, and asked folks not pass the documents around. But at this point it all seems a moot point and it’s such a nifty little circuit in its simplicity and how well it works with just a capacitor and a spdt switch to make a perfect current pulse to throw reversing single coils like in Kato and Tomix points.

 

he has some documents here for both the basic circuit but also to add leds for a fancier control panel, a power up reset of leds, and circuits for firing chains of points like for a yard routing with a single switch throw. Unfortunately they are written by an electrical engineer and not oriented to a more basic level of most model train folks. George was always so good at answering questions and I was trying to help him write them to a more basic modeler with little electronics experience. The basic circuit is dirt simple and can easily be wired up on just a regular terminal strip. Adding leds is just wiring in leds and resistors. The reset and chain circuits are a bit more complex, but he has diagrams for them all.

 

I can try to answer some questions, but I’m not an ee, just an old electronics hobbyist with limited knowledge.

 

RIP George, folks love the circuits and it’s a nice little legacy for your model train hobby.

 

cheers

 

jeff

1292189937_BCDPanel.pdf 465468508_Common-anodeLEDIndication.pdf 1422203699_EASYBCDE5V1.pdf 148074168_BCDPanelWiring.pdf 1092269304_ToggleSwitchYardControl.pdf

[brill27mcb]

My understanding from posts that he wrote on discussion groups was that George had indeed sold an article to a model railway magazine, but they simply never published it. Nonetheless, he was then bound by their agreement and could not publish the circuit drawings himself. He found himself confined in a legal box, but tried to find ways to help people in spite of that. He was not acting in some "oddball" way, just being legally careful.

 

Rich K.

[cteno4]

yes only others upset with him for not wanting it published on the web called unfriendly names. George was super nice guy and very helpful even with absolute beginners I would steer to him. He was very generous with his time and pleasant to deal with, I had fiddled with some simple pcb layouts on breadboard pcbs for folks that wanted to solder it all up and George was sort of adamant that that was not needed as the simple terminal strip wire up was easier, but he got some would want things soldered up. It is super easy it’s just some like things soldered down and looking cleaner and it was easy to solder small screw terminals down.

 

Last I talked to him about a year before he passed away (his health was failing then) he had someone lined up but no legal deal set yet, but he was reading it for an interested magazine and why he kept up the docs off the web as that would have sunk the deal with them. I was helping him some revise a manuscript to be a bit more average model rr friendly as his stuff was kind of written as an ee to a more electronics savvy audience. But the beauty of the BCD circuit is it’s so darn simple anyone could wire it with a cap and a spdt switch for under a buck per point and it’s very control panel friendly design.

 

All moot now I think. I tried contacting his family to no avail sadly.

 

jeff