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slimjerkins
Fireman
USA
1271 Posts |
 Posted - 10/06/2011 : 3:24:54 PM
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Jeff is on to something...
The circuit isn't complete unless the crossing frogs are connected.
Try this:
As for the 14-plus volts on the battery eliminator - that's not out of the ordinary at all. Battery eliminators do not normally deliver a nice clean well regulated and filtered power supply. If you were to look at the output of the eliminator on an oscilloscope the trace would probably look rather "lumpy." You are measuring the peaks of those "lumps." The manufacturer uses an average value for the output (~12V)
Let me know if this helps. I didn't test it.
-slim |
Edited by - slimjerkins on 10/06/2011 3:26:42 PM |
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jeffjan2001
Engine Wiper
USA
198 Posts |
Posted - 10/06/2011 : 4:25:24 PM
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ok, i think that this config from slim would cause you LEDs to be very bright for a very short period of time (short!). as drawn, the curent would forward bias both LEDs at the same time without going through the resistor. that would let out the "magic blue smoke" that all components need to operate. but the idea of getting a circuit is right. now, we have to figure out this little logic puzzle... [:-banghead]. i'm having printer troubles at the moment, so i can't draw on the print out and work pencil to paper as i would like [:-banghead][:-banghead][:-banghead].
to quote pooh, "think, think think..."
quote:
Originally posted by slimjerkins
Jeff is on to something...
The circuit isn't complete unless the crossing frogs are connected.
Try this:
As for the 14-plus volts on the battery eliminator - that's not out of the ordinary at all. Battery eliminators do not normally deliver a nice clean well regulated and filtered power supply. If you were to look at the output of the eliminator on an oscilloscope the trace would probably look rather "lumpy." You are measuring the peaks of those "lumps." The manufacturer uses an average value for the output (~12V)
Let me know if this helps. I didn't test it.
-slim
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Jeff
Spitton, Bailey & Wyre RR
"We'll get you there even if we have to get out and push!"
http://www.trainweb.org/sbwrr
Loosely Based on the Camas Prairie RR in Northern ID
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Carrie Creek
Crew Chief
USA
948 Posts |
Posted - 10/06/2011 : 4:49:41 PM
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Anders,
I am not seeing the need to indicate which leg of the crossing is hot as both of them should be all the time, even if they are only spurs. If you are using a commercial crossing the current should already flow through the crossing without shorting. Do a continuity test to make sure. If either you have a hand laid or it fails the test then you will need to cut some gaps on the frogs. If you make the frogs small enough you might be able to get away from powering them, I would definitely have the inside diamond guard rails dead. Your turnout indicators should tell you which leg you are operating on. If necessary add a lite on the leg from the turnout indicator for that route(dash lines on diagram).
You did not indicate if this is a single or double slip. if, so then, disregard this.
I did not show any wiring for the turnout indicators as you seem to know how to do this.
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Phil
POR (press on regardless) |
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slimjerkins
Fireman
USA
1271 Posts |
Posted - 10/06/2011 : 5:38:43 PM
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Anders/Jeff
I just tested my arrangement and it works. Remember - LEDs are current devices. Nothing happens unless we can get the juice moving along trough a COMPLETED circuit. Jeff - the little rectangle with an R in is a resistor. I didn't specify the value of the resistor. Don't know if you missed it or not.
The resistor limits the current flowing in the circuit to level that is below the breakdown voltage (blue smoke puff) value of the LED. It doesn't matter if the resistor is "before" or "after" the LEDs - just as long as it is somewhere in series with the power source.
Depending on the position of the switch only one LED will be forward biased and only THAT LED will light.
Hope this helps.
-slim |
Edited by - slimjerkins on 10/06/2011 5:40:21 PM |
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emccamey
Crew Chief
USA
908 Posts |
Posted - 10/06/2011 : 10:49:12 PM
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-slim,
Since the LEDs are being fed from the power source (not after the DPDT) - how does the indicators change? Correct the resistor can be after the LED , and also correct the circuit has to have 'continuity flow'.
The whole idea is to power the frogs and indicate which route the frogs are powered for. With DCC, this can be automatic with a reverser and no indication would be needed. With DC, the frogs have to switch.
The battery eliminator is applying full voltage and not the 'current voltage setting' being applied to the rails. This is a problem, the source for the DPDT has to come off the rail wiring so the throttle settings are matched.
A 3PDT switch can handle all this well - separate power for LED indicators - track power for the frogs. But the LED indicators have to be wired for continuity current flow.
-ed-
-ed- |
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slimjerkins
Fireman
USA
1271 Posts |
Posted - 10/07/2011 : 07:57:51 AM
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Okay - what I sketched and tested were different. Jeff is right - both LEDs are forward biased and I agree the 14 volts would most likely nail the LEDs in short order!
Jeff - You are correct sir! - my mistake!
I don't have my scanner in front of me or my sketching program but what if we were to take the two-LED/resistor combo and insert them between the lines going down to power the frogs? (that's the bit that I tested yesterday)
-slim
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Edited by - slimjerkins on 10/07/2011 08:35:44 AM |
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slimjerkins
Fireman
USA
1271 Posts |
Posted - 10/07/2011 : 10:32:47 AM
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Sorry for the confusion before.
THIS is what I tested and should have scribbled on the sketch:
Ed brings up some good points about the DCC vs DC issues and the LEDs being powered off of track voltage.
-slim |
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emccamey
Crew Chief
USA
908 Posts |
Posted - 10/07/2011 : 10:50:33 AM
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quote:
Originally posted by slimjerkins
Sorry for the confusion before.
THIS is what I tested and should have scribbled on the sketch:
Ed brings up some good points about the DCC vs DC issues and the LEDs being powered off of track voltage.
-slim
This will give the LEDs indication only when motive power is crossing the frogs. For the LEDs to light the circuit has to be completed. The separation of the power to the frogs and the LED indication is the better way to meet the intention of the indication and the powering of the frogs. I'll work out a graphic to give clarity - may be a few days before I can get to my computer and make the post.
-ed-
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slimjerkins
Fireman
USA
1271 Posts |
Posted - 10/07/2011 : 11:07:03 AM
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Ed - I agree that separating the indicator power and track power is a better way to go but the circuit above will illuminate. The indicator assembly is wired in parallel to the frogs. When motive power is not present current is only flowing through the properly biased LED and resistor. When motive power is present current flows through both the loco's motor and LED - and the LED will most liketly dim at that time.
-slim |
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Ironhand_13
Section Hand
USA
97 Posts |
Posted - 07/30/2012 : 6:37:25 PM
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This is an old thread I know, but is there a way to use a single DPDT switch to both a)switch polarity of the frog via DCC bus while b) using a seperate DC power supply to change an indicator light as on a dispatcher's panel or dwarf signal? Personally I doubt it, but wanting to see if any wiring gurus know of a way. I figure I'll have to use two DPDT's (or a DPDT and a SPDT) physically switched by my control rod to do what I want....correct?
I know I can use the bus to power my indicator LEDs, but I prefer to keep things seperate- bus power for the locos/passenger car lighting only, is my view. |
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bitlerisvj
Crew Chief
USA
926 Posts |
Posted - 07/31/2012 : 09:12:19 AM
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Nope, there are two different types of signals involved here. The DCC and DC don't mix and technically there is no polarity for DCC, but there is a RAIL A and RAIL B for DCC and these must be observed. You would need a triple pole double throw switch if there is such a thing. One of the poles would handle the frog for DCC and the other two poles would be used as a DPTD for directional lighting.
But, there are LOTS of easier ways to handle this. Most methods of doing this involve the contacts that come with the switching mechanism. Most switch motors, stall motors and dual coil provide plenty of contacts to do what you want if you use bi-polor (red/green) LEDs. Even Caboose ground throws provide switch contacts for manual turnout throwing. I presume you want to use the switch in conjunction with actually throwing the turnout right?
Maybe you can explain your turnout throwing mechanism and more ideas will come out here.
Regards, Vic Bitleris
quote:
Originally posted by Ironhand_13
This is an old thread I know, but is there a way to use a single DPDT switch to both a)switch polarity of the frog via DCC bus while b) using a seperate DC power supply to change an indicator light as on a dispatcher's panel or dwarf signal? Personally I doubt it, but wanting to see if any wiring gurus know of a way. I figure I'll have to use two DPDT's (or a DPDT and a SPDT) physically switched by my control rod to do what I want....correct?
I know I can use the bus to power my indicator LEDs, but I prefer to keep things seperate- bus power for the locos/passenger car lighting only, is my view.
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emccamey
Crew Chief
USA
908 Posts |
Posted - 07/31/2012 : 09:53:16 AM
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Separating the signal power from the track power is VERY wise (even with DC track power).
There is 3PDT switches (and they have very useful control options). One can use SPDT contacts for a variety of control purposes (turnout control, signaling, interlocking) if you build a bi-polled power supply with +. -, and common. A whole lot depends on the turnout control mechanisms.
Options abound, but knowing 1st - the turnout control, 2nd - the signal indications 'needs', 3rd - control panel configuration (local (along fascia), remote (central point), automatic, etc.), and track power used (DC vs. DCC).
Advise the conditions of the environment (turnout control, power supplies, signal needs, etc.), and there will be easy solutions to recommend.
-ed-
-ed- |
Edited by - emccamey on 07/31/2012 09:54:14 AM |
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Ironhand_13
Section Hand
USA
97 Posts |
Posted - 07/31/2012 : 3:07:41 PM
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Ok as posted when I started this thread, I use the push-rod controlled DPDT switch mounted under the layout, music wire up through a hole, wired to a seperate DC 12V power source, used to power a (future) status-panel indicator. Currently I have a remote Peco turnout whose aspect is indicated by a pair of home-made dwarf lights- Bi-polar 2-prong LEDs. I am DCC. I have a 'status panel' as opposed to a control panel because I don't have block occupancy or Tortoise-switched turnouts. I do have Blue Points coming to replace my DPDTs because of a couple angled turnouts that, well, it'd just be easier to use an RC cable for, and would handle better than my somewhat floppy dowel control. My remote Peco has the control rod attached to a small screen-door eye-hook screwed into the end of my dowel, so all my pushrods look the same. --->I do know that at the heart of a Blue Point is a DPDT, so nothing is really changing there. I have replaced all but two of my turnouts with CV/Proto:87-detailed ones, and have pre-wired them to power my frogs. These CV turnouts are done using Joe Fugate's method of a PC tie here and there. What that means is that there really isn't an electric connection via the points, as the DCC power goes through the PC ties, having properly removed the copper foil between the rails as needed, of course.
That help? |
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CN6401
Crew Chief
Canada
901 Posts |
Posted - 08/04/2012 : 8:20:33 PM
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Hey guys I think everyone missed the obvious.
LED's or light emitting diode will allow power to flow in one direction only.
The diagram shows two diodes 1 & 2 connected in parallel and the two leads from the pair of diodes are connected in series with one resistor
and then connected to power.
That said, if power is allowed to flow from A to B then diode 2 will light up. If you reverse the polarity diode 1 will light up.
I agree with a comment maid by someone else that 'Peco turnouts are self routing'.
I hope this helps demystify the problem.
Ralph |
Growing old is mandatory . . . growing up is optional
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A Touch of Yesterday©..............Weathered Rail Cars. |
Edited by - CN6401 on 08/04/2012 8:33:10 PM |
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Turnout DPDT light
