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Control panel and 2 aspect signal issue


669cpb
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I have been working on building a control panel using Seep PM1 motors, LED route indicators and 2 aspect signals.  As the signals were coming from China I built the panel whilst waiting.  The led route indicators work correctly and I added a bi colour led on the panel to show the state of the signal which is also working correctly.  Now the signals have arrived and so I connected them to the panel/point motor and nothing.

 

looking at the instructions, the red and green wires are on the negative part of the circuit with the black wire positive.  The instructions say the black wire is the anode.  

 

Now my my panel has the switches on the positive side.  So I can swap things around and can either have the panel leds all working correctly but no signal or the signal working but no route or signal indicators working.

 

The panel wiring is based on https://www.brian-lambert.co.uk/Electrical_Page_3.html

 

Seems odd that the signals operate differently. I thought leds were all wired the same way?

 

Any ideas on how I can get this working without rewiring the panel as it took about 2 days per panel to do and I have three, two completed so far?

 

Thanks in advance

Chris

 

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LEDs are wired the way you choose to wire them. The signals shown on the referenced page are wired common cathode. The signals are wired common anode. You will have to convert one or the other.

 

Model signals usually are common anode.

Edited by meil
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You do not need to change a thing. If you have point indicators wired one way and signals wired the other all you need is a simple diode / transistor interface to convert one to the other. I have used them on my layout with no problem at all.

 

If you would like a circuit diagram please let me know.

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10 hours ago, Rick-H said:

You do not need to change a thing. If you have point indicators wired one way and signals wired the other all you need is a simple diode / transistor interface to convert one to the other. I have used them on my layout with no problem at all.

 

If you would like a circuit diagram please let me know.

 

Thank Rick-H.

 

If you could provide a circuit diagram that would be great as I don't fancy having to rewire about 50 leds.

 

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669cpb,

 

As promised, here is my circuit diagram. It does a lot more than you have asked, so I will go through the stages, just in case.

 

I have shown both common anode and cathode panel LED's for you. I use the top one, ie common +12 volts, however the following circuit works with both.

 

The next stage, diodes and TR1 act as a very high impedance input. This stops the panel LED glowing when the switch is not connected to that LED leg. You only need one diode for each point switch.

 

This stage also works as an &Gate, so if you have say 3 points in a route that must be correctly set to clear the signal (light the green LED) then connect each point switch to a separate diode and it will work as follows: for green LED to light point A & point B & point C are high. If any input is low then the green LED will not light.

 

This "Gate" circuit works as a switch. If any input is low transistor TR1 will not switch on. So TR2 will see 12 volts, and switch on lighting the RED signal LED. This in turn will switch off TR3, so no GREEN LED. When all inputs to the Gate are high TR1 switches on, TR2 = off and TR3 = on, so GREEN signal LED is lit.

 

One last thing, if your signal comes with a fitted resistor in the common anode wire you do not need R5 in my circuit. However if the LED's are too bright you can add an additional resistor in R5's position. You will need to play with its value to get the brightness you want.

 

I have given a component list, however most NPN transistors and diodes will work. In fact I source my components from defective garden solar lights. In most cases its the solar panel that fails and they are un-repairable, however they all come with a transistor, a couple of resistors and a diode. A great source.

 

Hope this helps. Any questions please come back to me.

 

Rick

2 aspect signal interface.jpg

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I have tried this with a simple prototype but must be missing something.  At least I have the signal lit with the opposite polarity but both lights are lit with the red one not as bright.  

 

This is without anything connected to the diode.  If I then link the diode to the 0v DC to simulate input to the diode the red light goes out.  Not sure if the photos will help show what I have done?

 

Apologies if I have done something stupid here but have never used diodes or transistors before.

 

IMG_0657.jpg.b1aac7327c40a98569618f1e69db6d6f.jpgIMG_0658.jpg.a041c71f5a2ae1e5a123618588e4f407.jpg

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669cpb,

 

The way the circuit should work is with the diode open circuit or connected to 12volts the red LED should be off and green on. Connect the diode to 0volts and they should swap i.e. green off and red on.

 

I can not see what transistors you have used, so we may have a problem with base biasing. Please advise the transistors numbers, so I can check for you.

 

Rick

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I was using 3 x 2N2222A transistors.

 

I have found 2 BC108 so have swapped TR1 & TR2 for these.  I now have both lights lit and when I connect the diode to 0v the green led goes dimmer and the red brighter.  Whereas with the 2N2222As the green went out when connecting diode to 0v.  Will have to see if I can find another BC108 to try.

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Although the prototype separate circuit works, I have now connected to the control panel and only green is lit.  A trigger from the Seep point motor doesn't seem to work.  Based on diagram below I was thinking the output from D on Seep PM1 would be input to the diode?  D currently triggers the correct indication LED and signal representation LED on the control panel but the actual signal is staying green.

 

I'm thinking this is because the signal from D is positive and trigger to the diode needs to be negative?

 

Any ideas?

 

Chris

 

 

Screenshot 2019-04-28 at 08.16.03.png

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669cpb,

 

Are you saying that the signal LED stays green whatsoever the position of the point, or it's green and should be red? 

 

If the first one, we have a problem.

 

If the second option, move the input to 'E'.

 

If the input is high or floating then green LED should light. If input low then red LED should light. It doesn't matter which side of the point you connect too, you just need the correct signal indication.

 

I don't know the internals of the Seep switch, but assume it's a change over switch with 'F' being the common contact. So the input would see +12volts or close to zero depending on the switch position of the point.

 

Hope it helps.

 

Rick

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Rick,

 

Yes the green LED stays on regardless of the point position.  I have tried the trigger on both D & E and just green.  

 

Here are the PM1 wiring and the signal diagrams, if they are of use.

 

Chris 

IMG_20190429_0001.jpg

Screenshot 2019-04-29 at 07.30.56.png

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No I don't think a bridge rectifier will help.

 

I think the problem is that the LED plus 1k resistor is causing too much voltage drop and is therefore not switching off the first transistor, hence only green LED on.

 

What I think we need is a pnp transistor for the first stage. In effect swap tr1 position with r2 position and change tr1 to pnp type. Let me try some ideas.

 

Rick

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Here is a circuit that might work

I haven’t tested it

The resistor with the signal may not be necessary

With the point switch as shown then the voltage at the bottom of the green LED should be 12V(assuming a 12V supply) less the forward voltage of the diode (IN4001 or similar), if this is less than the forward voltage of the LED then it shouldn’t switch on.

I would use 1K resistors for the Signal LEDs

178725933_LedsSignalV3.jpg.ffb01d74740edc76d972f219ffbc34bc.jpg

Hope this helps

 

John

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I think a much simpler solution just requires TR2 & TR3 and the two 10K base resistors. If you have wired your panel exactly as Brian Lambert has in the circuit you showed. Then connect the Collectors of the two transistors to their respective LEDs in the signal and the emitters to the 0V connection as in Rick-H's diagram. Instead of connecting the 10K base resistors as shown simply connect them directly to terminals D & E on the SEEP PM1. The way the circuit works is that as the switch is used to switch between the panel LEDs it also switches between the transistors which when triggered switch on their respective signal LED.

 

Richard

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