Model Railroad help

Thread Starter

maassmi

Joined Oct 30, 2011
81
Here is my revised drawing. I was using a DPDT (on) -off- (on) switch, but I like your switch better and will use your switch out put instead of what I have shown in my revised sketch. Here is my revised sketch:
 

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SgtWookie

Joined Jul 17, 2007
22,230
Scared - Not scared of the project, it was just scarry that you SgtWookie was thinking and doing the same thing for me.
Oh, OK. You'd posted a request last night for a "real parts" layout sketch after I hit the sack; I'd just seen it.

Trying to draw it out for me so that I might understand it better.
It should be fairly easy now. Just compare what I've drawn to the actual parts, and install them the same way I've shown them.

would love to keep an LED so I know that power is flowing through properly.
That would be just a 1k to 2k resistor in series with an LED, color of your choice, connected across the capacitor. The cathode of the LED (the shorter lead) should be electrically connected to the negative terminal of the cap.
Also in your new sketch, it appears that the diodes are pointed in different directions from your first diagram you sent.
The banded end of diodes indicates the cathode end.
In schematic representations of diodes, the arrow (triangle) "points" towards the cathode end.

My drawing was based on your diagram.
I see that.

I used long and short legs on my drawings of the LED and the capacitors to illustrate what I see in the photos I am finding on the internet.
I don't know how you got them backwards then.

Also, the resistor on the LED should really go on the more positive (anode) side (the longer lead). I do that so if you accidentally short the anode of the LED to ground, nothing bad will happen.
 

SgtWookie

Joined Jul 17, 2007
22,230
Here is my revised drawing. I was using a DPDT (on) -off- (on) switch, but I like your switch better and will use your switch out put instead of what I have shown in my revised sketch. Here is my revised sketch:
Everything to the left of the switch is OK.

A SPDT (on)-off-(on) switch has just 3 terminals, as I showed in my prior post.

If the three terminals are evenly spaced, the center terminal will be the common.

If the three terminals have two together and one far away, the furthest one is generally the common terminal.

You are showing a switch with six terminals. I don't know where all the extra terminals came from, do you?
[eta]
Ahh, OK - if you use the switch drawing I put up instead of what you have drawn, it'll be OK.
 

Thread Starter

maassmi

Joined Oct 30, 2011
81
On the LED, I do have the resister attached to the longer lead. Can I use one of thse resisters that I already have (photo)? Can I use this resister in place of the other resister needed as well, or would I need a different one or need to use several of them?
 

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SgtWookie

Joined Jul 17, 2007
22,230
On the LED, I do have the resistor attached to the longer lead. Can I use one of thse resistors that I already have (photo)?
The resistance that is required is 1k Ohms.
You show a package of 100 Ohm resistors. You would need to connect 10 of them in series to equal 1k Ohms. This would not be very practical to do; you would need to use a lot of shrink tubing to insulate them, and the resulting assembly would be somewhat fragile.

Can I use this resister in place of the other resister needed as well, or would I need a different one or need to use several of them?
You would be much better off to just get a 5-pack of 1k resistors.
I put the Radio Shack catalog number for them in the board layout.
 

Thread Starter

maassmi

Joined Oct 30, 2011
81
I've the capacitor and yes the wires come out of each cap. On the side of the "tube" are arrows. I assume that this means something. Which end goes into which section of the bread board. I don't want to put it in backwards.
 

SgtWookie

Joined Jul 17, 2007
22,230
I've the capacitor and yes the wires come out of each cap.
You mean out of each end of the cap.

On the side of the "tube" are arrows. I assume that this means something.
Look at those arrows; there is a '-' sign on the arrow which means the arrow is pointing at the negative terminal.

Which end goes into which section of the bread board. I don't want to put it in backwards.
The arrow points at the end that needs to be connected to -VDC.
 

SgtWookie

Joined Jul 17, 2007
22,230
OK, I've posted the schematic and the graphical board layout of the simple CDU already; here's the schematic translated into what the parts look like (except I don't know what your AC transformer looks like)


 

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Thread Starter

maassmi

Joined Oct 30, 2011
81
SgtWookie, Based on the schematics that had been posted earlier, this is a sketch of the board I put together. I have not soldered it yet as I would like you to look at this before I make it permanent. Am I close, or way off. I am now looking at your simplified drawing and it has fewer eliments than before by far. Take a look at what I and let me know what to move or remove please. I hope I have not made it too confusing.
 

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Thread Starter

maassmi

Joined Oct 30, 2011
81
I think I drew what you had provided me in an earlier posting you sent. This drawing is what I have actually put together and would like to know if I got it right before I solder it.
 

Thread Starter

maassmi

Joined Oct 30, 2011
81
Let me try that again. I built the CDU based on your simplified bread board sketch and added the green LED back into it. This sketch is of what I built and I would like to make sure I got it right before I solder it.
 

SgtWookie

Joined Jul 17, 2007
22,230
If you lay the parts out with wires long like that, you'll probably wind up with shorts all over the place.

I had the colors for the AC wiring as blue; meaning that there was no real significance to polarity - it's AC.

I had the wiring between the base, collector, resistor R1 and the positive rail as red, because it was all positive. You changed it to blue, which is what I was using to indicate AC.

Electrically, the two diodes on the right are connected correctly. However, their leads are WAY too long.
The resistor for the LED should go from the pad supplying power to another pad that is not already used. Then the anode of the LED should be connected to this formerly unused pad. Then the cathode gets connected to the negative rail.
 
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