Wiring LED Power Indicator on Control Panel Question

The easiest way would be to use LEDs with prewired diodes and resistors that would run on track power. One lead to the block side of the switch and the other to ground. Search ebay, that's the least costly route. If you are running conventional, they may not light at lower voltages.

Thank you John.  I am running DCS, not sure if that makes any difference.

Darren

That should work better. I have some cool white and ww 5mm. You could color them with paint. I will send you one of each if you would like to experiment. Just email me your address.

I had a similar situation.  My final solution was to replace my SPST switches with DPST switches.  The DPST switches fit the same envelope as the SPST switches so space was not an issue.  Used one pole to control track power and DC on the other pole for the LED.  This eliminated the brightness issue at low voltage levels.

Radio shack has some prewired LEDs in holders in Red and Green. Here's a link to a Red one...

https://www.radioshack.com/pro...-red-led-with-holder

If you wire this in parallel with your track lead that the switch turns on the track, it can show that the track is turned on. I would put a diode in series with it, or better you can put a diode in series with all the black common leads that normally go to the outside rail. Tie all the LED black leads together and connect one diode (1N4003 or equiv.) to the U terminal or outside rail point. A track voltage of 18 VAC will result in approximately 12 VDC effective to the LEDs by nature of the fact that only a half wave of the AC voltage will be conducted by the LEDs. Tying all the black leads together and to one diode connected to the common side of the AC will protect the LEDs from the reverse peak voltage of the AC. The arrow on the diode (1N4003) should point to the common or U terminal.

First, thank all of you for responding.  I spent some time this morning, attempting to make a "basic" diagram of what I have, so all of you can see.  It always helps me explain something better with a picture rather than words, especially in this case where I am novice at best!  I have not purchased the LED's but I thought 24v would be best since the Z4000 spikes to 21v.

What I am hoping, since I have never worked with on/off switches, indicator lights, etc, is that someone can please look at my picture and "Connect the dots" for me.  I am using terminal blocks, I just left them out of this picture to simplify matters.

I my mind, power from the + terminal to the on/off switch, then to the "+", red wire, of the LED, which would be paired/twisted and then connected to the center rail of the track.  This way once the switch is in the "On" position, power would flow to the LED, light the LED and power the track.  If that is correct, then where does the "-", black wire, on the LED go?  Does it go back to the "-" terminal from the power source or to the track?

For some reason I cannot add attachments at this time, once I can I will post the picture I made.

Again, thank you all for your help.

Darren Caruso

Here is the picture

Here is how I did mine.  Let me know if you'd like to know what resistor I used.

Here is a diagram. The 21 VAC doesn't matter. Just do it like this.

No offense guys but I think I'm more confused after your drawings, lol!  

Charlie, if I use LED's with built in Diodes will I still need the part you have labeled IN4005?  and I'm even sure what that is.

Cjack, I obviously need to educate myself on electrical drawing symbols because the SPST switches I have only have two pins, a 1 and a 2.

All I am looking to do is to have the LED illuminate when I move the toggle switch to the "On" position, and have power supplied to that "block" of track.

Thank you,

Darren

Darren, With a built in diode you would not need the diode in my drawing.

Thank you, just one more question, is the ground from the LED wire going back to the terminal block or to the track?

Darren

Darren, It goes to a barrier strip in the control panel tied to my common ground.

Darren Caruso posted:

No offense guys but I think I'm more confused after your drawings, lol!  

Charlie, if I use LED's with built in Diodes will I still need the part you have labeled IN4005?  and I'm even sure what that is.

Cjack, I obviously need to educate myself on electrical drawing symbols because the SPST switches I have only have two pins, a 1 and a 2.

All I am looking to do is to have the LED illuminate when I move the toggle switch to the "On" position, and have power supplied to that "block" of track.

Thank you,

Darren

 

I don't know of any 12 VDC prepackaged LED assembly that has it's own diode in the package. The LED itself is a diode. The problem is that running it on AC will exceed it's reverse voltage rating which is usually only about 5 vdc. So I say you have to put an external diode in series with it. AND you only need one diode for as many LED assemblies you have because one diode will protect them all.

That drawing shows THREE spst switches. I included more than one so that you would see the typical wiring scheme where there is usually more than just one block to be turned on or off. Sorry for the confusion. And yes, each spst switch only has 2 pins.

In the drawing, if wired as shown, the LED will light when turning the switch on.

You're right, Chuck. I can't find any with diodes. Search for prewired LED 18vdc. they are about 70 cents apiece on ebay.

Chuck, thank you, that helps clear up my confusion.

Charlie, thank you for clearing up my ground question.

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 Guys, these are the ones I found, but now that I understand the wiring I think I can purchase the diode and complete the project.

Just to be clear.  Are you buying the 24V GREEN LEDs and installing the single diode to work on your Z-4000 transformer?  As I undertstand it, you are operating DCS with the Z-4000 set to, say, 16-18VAC as recommended by MTH?

I was planning on using the 24v LED's because the readout on my Z4000 is consistently between 20 and 21 Volts.  I thought this was the "safe" way to go.  Am I overthinking this and only need 12v LED's?

Darren

24 VDC LED assemblies are not going to work well with 18 VAC. They naturally rectify the AC to using one half of the sine wave and the effective DC voltage for lighting them is only something like half the peak or less...so around 9 to 12 VDC which is perfect for 12 VDC LED assemblies. The addition of a rectifying diode in series is to protect the LED from reverse peak voltage damage.

One if the above diagrams shows a diode reversed and across the LED to protect it, but that consumes power thru the resistor for the reverse AC cycle. Better to put the diode in series with the LED I think.

Chuck, thank you!  You obviously are very knowledgeable when it comes to electronics, I am learning as I go.   In fact, I have had to look up some of the terminology so I can understand what you guys are talking about.  I will look into 12v LED's.

Darren

cjack posted:

One if the above diagrams shows a diode reversed and across the LED to protect it, but that consumes power thru the resistor for the reverse AC cycle. Better to put the diode in series with the LED I think.

Chuck,  I assume your referring to my diagram.  My Uncle who is an EE drew the circuit that way, so that's what I built.  It's been working fine for a couple of years now.  I can't debate the plus or minus of doing it the way he drew it or the way you've stated because I don't have the expertise of my Uncle or yourself.  I was just sharing a solution I knew had been tried and is working for me.

MichRR714 posted:

cjack posted:

One if the above diagrams shows a diode reversed and across the LED to protect it, but that consumes power thru the resistor for the reverse AC cycle. Better to put the diode in series with the LED I think.

Chuck,  I assume your referring to my diagram.  My Uncle who is an EE drew the circuit that way, so that's what I built.  It's been working fine for a couple of years now.  I can't debate the plus or minus of doing it the way he drew it or the way you've stated because I don't have the expertise of my Uncle or yourself.  I was just sharing a solution I knew had been tried and is working for me.

That's fine. I'm an EE and respect the design. In a way it protects the LED even better, but it's just that it consumes power on the negative half cycle and I guess I'm thinking green these days . I've been using the series diode with 12 VDC LED assemblies for 10 years now and they work well, no issues.

Charlie & Chuck, I want to thank you both again for taking the time and helping me work this electrical question out.  After I made a drawing of the plans it doesn't appear so complicated anymore.  I purchased some 12v LED's and a 10 pack of the IN4003 diodes.  I have 15 SPST toggle switches that I want to install on the control panel; so once I get to work on it I'll let you guys know how it went, hopefully successful!

Darren