I have an electrical problem going to a Tortoise switch machine.
1. The switch on the control panel is a DPDT. Also connected to LED lights on panel
2. One side of switch is sending 7.5VDC to the machine. The other is zero
3. All wiring appears to be good . This was a working machine
4. The LED does not light when the switch is thrown to that side.
Would this be a bad switch ( DPDT)?
How exactly is this all wired together, and what power supply are you using? 7.5V seems slightly low for a Tortoise.
And what are your voltage referenced to? If you have one probe on the negative of the power supply and then measure the voltage going to the tortoise, one side will have some + volts, and the other will be zero. If you flip the toggle, the side that was some plus voltage will now be zero, and the side that was zero will now be some plus voltage.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
If it all worked OK before, it sounds like a loose wire or a wiring short if wires are touching one another.
Rich
Alton Junction
LION rule TORTOISES!
If you are using a common return BE SURE IT IS GROUNDED! Stray voltages will eat you up every time.
Why anybody would use two where when one will do is beyond me. And well beyond my budget.
LIONS do not put LEDs in series with a Tortoise. Remember LEDs *ARE* rectifiers. Put them across the circuit (in parallel) with their own resistors. Then you can have as many as you need: at the control panel, and lighting signals on all tracks.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Standard DC installation with criss cross & center posts going to switch machine. I started checking the DCV at the machine to a terminal then to another terminal and then to the panel. As mentioned when the toggle is turned one way Green LED is on. When toggle is thrown there is nothing. Tortoise is not activated and Red LED is out.
Harold
And you're convinced that all wires are tightly connected and not touching one another where they shoudn't be touching?
hwolfGreen LED is on. When toggle is thrown there is nothing. Tortoise is not activated and Red LED is out.
Your RED LED is reversed. TURN IT AROUND! Remember LEDs are rectifiers.
Sounds like a bad LED.
Jim
1. Double checked all wires and connections. They are soldered or attatched to a terminal strip. All wire connections are tight with none touching
2.As far as the LED. I have 5 more wired exactly the same with no proble. Remember this was a working switch
3. Couldn't it be as simple as a DPDT toggle gone bad. If so ,how can I check this?
I would agree with you Jim,if it worked before,it has to be the LED. Or maybe a loose wire,in that connection.
Cheers,
Frank
I vote for a bad connection somewhere. How are your wires attached to the Tortoise? If you're using a circuit-board edge connector, try moving it around a bit. That might be the weak point.
You can check the LED easily by just jumpering a wire across is. Your voltage is low enough that the missing LED in the circuit will not hurt anything. If it works when you bypass the LED, that's your answer.
And yes, sometimes toggle switches just go bad. I've had that happen, too.
It takes an iron man to play with a toy iron horse.
Harold,
Do you have the small electrical jumper cables? I you do ,put a jumper on one end of the LED and the other end of the jumper to the other end of the LED,,IF the switch machine works,you know the LED,is open.Do a continuity on the DPDT,with power off,to both poles,IF you don't get continuity,with toggle is thrown both ways,contact bar inside may be bad..
How do you have the LEDs wired? They need to be wired back to back with each other, then the pair inserted into the wire goign to either pin 1 or pin 8 of the Tortoise. If the LEDs are not connected opposite each other, it will only work in one direction.
The LEDs are wired as follows
Both red wires going to black wire of other LED.
One LED wired to center post of DPDT Toggle
Other going to Tortoise.
Don't forget these have been working with this configuration.
Beautifully opaque. Have you tried applying about 9VDC directly to the 1 and 8 connections on the tortoise to see if it is working?
Joe
All of the above suggestions make sense.
This may require a bench test to isolate the faulty component.
Have you done anything recently to the "circuit"? Or did this problem just start occurring without any intervention on your part?
hwolfThe LEDs are wired as follows Both red wires going to black wire of other LED. One LED wired to center post of DPDT Toggle Other going to Tortoise. Don't forget these have been working with this configuration.
are you saying that the LED is in series with the Tortise?
if so, can an LED handle that much current? did it burn out?
edit: what are red and black wires going to (if LED, to cathode or anode)
are they wired as shown in one of the following figure?
greg - Philadelphia & Reading / Reading
It is wired like the TOP picture above
Then it is certain to be a open Red LED,,Burnt out.
Let me show my ignorance of electronic circuitry with this question.
Would a burned out Red LED prevent power from reaching the Tortoise?
It is interesting to me that nothing works when he flips the toggle on the DPDT one way.
Not the Red LED and not the Tortoise.
richhotrainWould a burned out Red LED prevent power from reaching the Tortoise? It is interesting to me that nothing works when he flips the toggle on the DPDT one way. Not the Red LED and not the Tortoise.
yes
i believe he has a combination of the two drawings. The first doesn't show the switch. The bi-polar LED in the 2nd figure is replaced by the two LEDs wired as shown in the 1st drawing.
The two LEDs are wired opposite one another so that only one LED passes current depending on the polarity of the voltage applied. Same with the bi-polar/color LED. The dpdt switch reverses the voltage and the current flows through one LED or the other..
if the one (red) LED is burnt out, there's no connection to the Tortoise for the associated switch position. and the green LED, that still works, is reversed biased and blocks current flow. The Tortoise only sees the one voltage and therefore never changes position.
I thought i read that the Tortoise is equivalent to a 600 Ohm resistor. Assuming 1.4V LED max voltage and 7.5V operating voltage, the LED current is ~10ma. How close is this to the max current of the LEDs?
edit: you can check if the LED is bad by measuring the voltages across both LEDs. There should only be ~1.5v across the LED that works. If the LED is burnt out, the full operating voltage, 7.5V, will be across the LED.
If there's a problem with the switch, there will be no voltage across the LED.
Thanks, greg.
There must be a better way to wire this entire circuit to prevent loss of power to the Tortoise if the LED fails.
Isn't there?
richhotrainThere must be a better way to wire this entire circuit to prevent loss of power to the Tortoise if the LED fails.
It would be nice to have an LED that indicates that there is simply voltage across the Tortoise, but it wouldn't indicate that the Tortoise actually failed. This circuit is better because it indicates that current is going through the Tortoise. There's a problem if the LED isn't lit.
Hopefully the cheap LED is simply burnt out, but it could still be the one side of the Tortoise
It's unusual that an LED can be in the circuit path like this and provide such a definitive indication of a problem.
I vote for miswired. Disconnect everything and start at the switch. Test that you have DC power before and after the switch. Throw the switch and check that it is reversed. Then add components one at a time and test. You will eventually find the problem.
An LED installed improperly will block DC current flow. Check them carefully.
Dave
Lackawanna Route of the Phoebe Snow
Phoebe Vet I vote for miswired. Disconnect everything and start at the switch. Test that you have DC power before and after the switch. Throw the switch and check that it is reversed. Then add components one at a time and test. You will eventually find the problem. An LED installed improperly will block DC current flow. Check them carefully.
Yep, that is what I would do too,
I have had 64 Tortoises on my layout for the past 10 years, and none has ever failed. I see no real reason for using an LED to indicate if the Tortoise is functionally properly. Worse yet, if a faulty LED shuts down the Tortoise, what good is that?
I wouldn't consider it a bad circuit design because power is cut off when the LED fails - once known to be working, LED lifespans are measures in 10's of years, assuming you don't do something silly and feed them without current limiting, or purposely overdrive them to make them super bright, or twist the leads so much that it breaks the fine bonding wire inside, or subject them to excessive voltage in the reverse direction. In this case it provides a pretty positive indication that something is wrong - since it works one way and the one LED lights, it's not the switch, power supply, or Tortoise. The two back to back protect each other from excessive reverse voltage, and the Tortoise motor itself provided current limiting well within the allowed range for common LEDs. It's actually a quite elegant design to get panel indicators without running more than 2 wires to the Tortoise, that as mentioned also indicate if the Tortoise actually moves, since the LEDs dim while in motion and then go to full brightness at the end of the throw.
Randy, I'm not sure who you were addressing your comments to but I, for one, don't consider it a "bad circuit design". I just don't consider it necessary.
If the system was working and suddenly quit, I find it hard to believe it is miss wired. I would bridge the gap between the leads of the non working LED and see if the Tortoise works. If it does, it's the LED, if not then a search of the entire circuit will be required. I agree with Randy, the tortoise power draw is well within the limits of the LED and the life of the LED is quite long. I did however have one of my 36 bi-color LEDS go bad after about six years. Can't remember if the Tortoise quite or not.
richhotrain Randy, I'm not sure who you were addressing your comments to but I, for one, don't consider it a "bad circuit design". I just don't consider it necessary. Rich
I don't understand why not,,what the red LED,tells you that the turnout is set for the diverging route and the green LED,for the straight route,on his control panel.
floridaflyer If the system was working and suddenly quit, I find it hard to believe it is miss wired.
If the system was working and suddenly quit, I find it hard to believe it is miss wired.
Maybe not miswired, but loose wire or wires touching where there shouldn't.
I cannot recall if the OP mentioned anything about messing with the wiring, but had any maintenance work be done recently where the wiring was in some way affected?
Of course, since the Red LED is being questioned, the OP could swap it out for a known good one or test in with a low voltage battery or with a resistor attached to a 9 volt battery.
Speaking of the OP, we haven't heard from him since late last night.