Led panel circuit

If the red line from the power supply is positive, then it should connect to the longer lead on the on the leds. 

Each led should have at least a 470 ohm 1/2 watt resistor on one of the leads, not a single resistor for the entire circuit.  The 470 ohm resistors would be the minimum for a 20ma LED on a 12 volt supply circuit.  You could easily go up to 1000 ohms or more depending on the light intensity you want.

With the circuit as drawn, if the power supply positive is red, the leds would not light and in as much as the resistor is much to small, you most likely would not have burned out the leds.  If the red power supply is negative the leds may have to be replaced.

To correct the circuit, make sure the red line is positive (check with your meter) remove the 150 ohm resistor and add a 470 ohm or larger resistor in the positive lead to EACH led.  (The resistor could be in either lead but if in the positive lead, is just good practice.)  The longer wire on the LED is typically connected to the positive supply.

What is the device in the red lead between the power supply and the switches? A terminal strip?

Bill Feairheller

Ummm... at the risk of

Ummm... at the risk of sounding like a shill...  have you taken a look at the Berrett Hill Touch Toggles? (They advertise here...) You'd have indicators, turnout control, and turnout motor operation all in one plug-and-play system.

I'm anxiously awaiting the release of the Kato turnout controller (Real soon now!) myself to install them on my T-Trak Inglenook.

< < grinning And at the moment, their ad is right at the top of this page.

Dropping resistors

Have you verified that each LED is working?

Assuming general convention that the long lead on the LED is cathode, you appear to have it drawn incorrectly for LED polarity, assuming red is positive 12V.

Each LED should have its own dropping resistor.  12V-3.4V=8.6V needs to be dropped between the supply and the LED.  Assume 20ma and R=E/I=8.6V/.02A=430 ohm.  Suggest a resistor value between  0.5-1K ohm. 1/2W should be sufficient.

LED Panel Circuit

Bill,

Thanks for the comments.  I used terminal strips where indicated. In order to minimize the number of joints on the main bus, I use a jumper on some of the terminal strips shown by a straight line in red or green.  I will have to double check which is lead positive and negative per your question.  I have some 1.5K ohm 1/2 watt resistors that I used for the power on/off indicator LEDs on the staging tracks that work fine - would they work in this circuit?

John

Turnout Controls Have Built-In DPDT

Appreciate the comment but these manual turnout controllers come with integrated DPDT switches that activate when the controller is pulled and/or pushed.  I am merely used three of the contacts to route power to the LEDs for turnout indication.

Resistors

Thanks for the comments.  I will double check what is positive and negative and reroute as necessary.  That is one reason why I used the terminal strips.  I will pull each LED and double check that they are still working before adding the resistors.  I will also take out the current resistor.  I have some 1.5K 1/2 watt resistors that I used for the power on/off LED indicators for my staging tracks - will those work in this circuit??

Voltage to start with.

I used old transformer, took center tap which was 6.5 volts.  then went to diode converted to DC and put capacitor in curcuit.  Then applied resistors at led location to each led. My circuit for LEDs covers the whole layout.  Work indicators off of Tortoise machine extra switch terminals.  using 3mm LED, need to be under 2 volts.  Good Luck.

Resistors for LEDs

John,

The 1.5K resistors will work,but the leds may be rather dim.  Try one in series with one of the LED connected  to your power supply to see if is bright enough.  Also this will tell you if the LED are still OK and which lead of the power supply is the positive lead.  Just connect the power supply to a led through the resistor.  If it doesn't light, reverse the power supply leads and check again. If it doesn't light, you may have burned out the led.  If it does light, check to see if it is bright enough.  If it is not, get some resistors between 470 and 1K ohms  Remember you need one resistor for each LED.  If the LED doesn't light, you may want to check each of the LED you used in the circuit test

Bill