I have finally placed all of my track and turnouts on my main level of my layout and I am now ready to develop my control panel and wire all of the blocks. As I have said in several of my posts, my background is in electrical/electronics, however it's been almost 10 years since I did any serious electrical design work, and I fear that I am now very very rusty. I'm hoping all of you model railroaders who are into electrical schematics will help me do a double check on my schematic to make sure I'm not screwing up.
A couple of givens. I'm using HO scale and DC, not DCC. My control panel will be 1/4" birch plywood painted white and mounted (probably in a box with an umbillical cord so that I won't have to always sit in the same spot to operate my layout). I developed a print that I will convert to a decal to put on the control panel and then mount my toggles and LED's in the proper place on that print.
Here is my control panel layout.
The main deck is complete. I'm building foam mountains to raise the level for the upper deck where the Hightimber Logging Camp will be and for the Gold mine and Marble Quarry. I see I labeled the Gold Mine and Marble Quarry wrong. It should read Upper Deck not Lower Deck. Both of the these two sections will be essentially directly over sections of the main deck. The bulk of the middle of the main deck will be the valley floor where the Village of Hightimber is located. The track from each upper deck section will connect to "Block C" which is where the "Train Elevator" will be hidden inside a mountain allowing me to raise my train from the main deck to the upper deck. Total rise will be actual 5" which, if I'm right will be HO scale 36.25 ft.
Where Block D intersects with Block E and Block F, those intersections are insulated frog crossovers, not bridges and therefore will not cause any electrical problems.
Now for the electrical schematic. (I found this nifty free software called TinyCad made specifically for designing electronic schematics--I like it.)
What I have drawn here is only the schematic for one block. It includes the DPDT toggle with center off position, and four LED's. (It also includes a small section of the control panel in the upper right hand corner to shown how the LED's would be positioned on the control panel.) My intention is to mount a red and a green LED at each end of the electrical block on my control panel. Then when the track polarity is correct (for reversing loops etc.) you should see matching colors lit up for adjacent blocks. In effect, if Red is lit up on Block A, then Red should also be lit up on Block E. If opposing colors are lit, then the blocks are not set up and ready for an engine to enter the block. Also if the toggle is in the center off position, none of the LED's would be lit, showing that the power to that block is off.
I have only drawn the schematic for block A. All of the others will be identical except block C. It will have four red and four green LED's instead of two each, as the Upper Deck control panel needs to have the LED's adjacent to each of those blocks there also.
I have not shown the wiring for the elevator. It will be AC and separate from the other wiring. I also have not shown the wiring for the turnouts. Those will be developed later. Right now I am using the slide switches that come with the Atlas switch machines, but I will change that to toggles, push buttons, and capacitor discharge when I design that part of the schematic.
At this moment I have 12V+ and 12V- printed on the schematic. (that is only a starting point. I will revise the voltage as necessary.) Also I have not indicated the size of the resistors.
Here's some of my questions (from being so rusty). Have I made any critical mistakes in the actual schematic?
Will it work as I have designed it?
Do I have the LED current flow in the proper direction for Red to represent + and green to represent - polarity.
When I add the other blocks to the feeder, will I have any feed back problems?
With what you see from these drawings, what is the size of resistors that I need?
Many thanks in advance for your advice.
Woodlandtoots
I don't think it is really +12V and -12V on the bus, correct ? It is really just 12V and a return with the polarity changing towards the block depending upon which way you are flipping the block switch (i.e. wired as a reversing switch). Make the resistors 1K 1/2W resistors (if it truly is just 12V and a return). You should be fine with that. If I assume that the +12V is really +12V and -12V is the return then none of the LEDs will ever light. The reason is that you have the return (which is negative with respect to the +12V) tied to the cathodes of all LEDs. If you flip all of the LEDs around then when the switch is in the up position the top two LEDs will light and when it is down the bottom two will light.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
I told you I was rusty. I had questioned in my brain if I had the LED's reversed or not. Thanks . You're right about the 12V- really being the return for the 12V+. Again being rusty caused me to forget how to notate it properly. I'm not sure in the end if I will wind up with 12v, 16v or something else. A lot will depend on what transformer I use to power the controls. I haven't addressed that question yet. Keep the comments coming. I need them to scratch the rust off my brain.
Hi, nice looking circuit, and easy for an operator to see if the tracks ahead are in phase to continue onto. Wish I'd thought of something like it; think there are burns on several of my loco wheels from crossing into an out-of-phase area.
I do have a comment or two (don't I always?) for you to consider: I assume you will feed your track with 12v only, not the 24v that you indicate by "+12v & -12v". That terminology says that there is a 0v level somewhere that isn't shown here. It's less confusing to relabel the "-12v" as "0v", or something like "common".
The diode resistors need to drop the voltage, hence current, to what the diode will handle. If you are using 5ma rated or 60ma diodes or whatever, the values will be different. I usually expect a conducting diode to drop a fraction of a volt across itself, with the rest being dropped by the resistor. To make it easy, I just say the entire supply voltage is dropped across the resistor. now use the old V=IxR formula to figure out what ohms you need. If V=12v and I=20ma (.020A), then R=(12 divided by .02), or 600 ohms. The diode will glow brighter or dimmer if you go outside that value.
Now for the proverbial monkey-wrench.... How do you control loco speed? If you drop the track feed voltage by much, the diodes will get dimmer and finally quench out. You will only have useful light from them at speed. If that doesn't bother you, no harm will come from being underfed.
I can't see any reason adding more blocks would be a problem. Just be sure to gap both rails at both ends of the block.
I like your idea to use an elevator to get between levels. With only 5" between levels, will there be enough room to get in there to service whatever you mount under the upper subroadbed, or above the lower one? Can any component mounting screws be removed/reinstalled for fried sw-mach motors or uncouplers? Using a sawed off screwdriver and a pair of pliers to turn a strange screw at right angles is a pain..... don't ask.
As I started out with, nice idea! If you feel better trying it out, bench-test a unit before cutting holes in your panel, then.... Go for it! Have fun, George.
Two replies both saying the same thing about the 12V+ and 12V-. I'm sure getting the rust scratched off Thanks ever so much for catching that.
Since I will for all intents and purposes be only running one loco on the layout, dimming won't be a problem with me. Anyone got a great idea of how to alter the schematic to compensate?
The elevator will have all kinds of room to work on it.
Notice the notch in outside dimensions of the layout (right next to block c) That is all open space behind the layout. The frame of the elevator will hang maybe six or more inches off the back side and be made from aluminum angle. The front side will be covered by mountain scenery, but the back side will be 100% open aluminum framing for access to the entire contraption. The motor for the elevator and the sissor jack style lift mechanism will be mounted under the lift platform but behind the outside dimension of the layout. Therefore I'll have more than a couple of feet below the layout height to hold the entire mechanism. The actual lift platform will extend onto the layout but I'll only need the thickness of an aluminum angle (probably about 3/4" or 1" size) below the track height to make the correct alignment points to make the rails come in alignment. Right now my track is on corkboard with two 1" layers of foam below it. I'll remove the two foam layers and replace them with cork on 1/4" birch mounted to an aluminum angle which should hold the lift very stable. In a previous post I was pointed to a web site that showed how to build this kind of elevator. My layout has the ideal space to make it work. I can't wait to build it (I already have the motor--It came out of a paper shredder that the plastic gears stripped. The motor is more than adequate and would otherwise have gone to the junk pile.) But I doubt I'll do anywork on it until next summer or so. My goal now is to get the electrical controls working so I can use the reversing loops.
Keep the comments coming. I still have plenty of rust.
woodlandtoots-any chance of you posting pictures of your Marble Quarry construction progress?
thanks