Search results

  1. D

    Current limiting resistor power rating question

    I have LED with a 100ma rating, 4.5v voltage drop and 12v power source. The formulae I have been using call for a resistor of 82 ohms with 1w rating. I have a 100 ohm 1w resistor in series with this LED and it gets too hot to hold. What am I doing wrong?
  2. D

    Led Flashlight Help

    I have an LED flashlight that runs on 3 AAA batteries. I want to run it with a 12 volt battery. I have adjusted a dc to dc converter to 4.2 volts. The flashlight gets very hot. (It doesn't get hot when the AAAs are connected) I've checked my volt meter to see if the dc to dc converter was...
  3. D

    Transient Voltage question

    I have a DC motor controller powered by 2 12v batteries in series. (The controller is a 4qd Pro 150 which powers my locomotive. The leads from the batteries have a 30a fuse.) I would like to put a relay between the batteries and controller in order to turn off all power to the controller. I've...
  4. D

    AGU FUSE HELP

    I have a 60a agu fuse in my 24v dc train controller. After running for approximately 20 hours my engine stopped. I was going down hill at the time of the malfunction. This was after nearly one mile of up hill travel. The motors and controller heat sink were cool. The fuse looked fine and...
  5. D

    How to properly connect wires

    I need to connect wires from the controller on my locomotive to the 2 motors wired parallel. There is one lead from the controller going to each of the motors. The circuit is protected with a 30a fuse and the motors are 7.5a each. The system is 24vdc. The wires are subject to movement as the...
  6. D

    Bad Capacitor?

    I have a small board with several relays caps, transistors etc. The board sustained an impact and stopped working. I've eliminated the power supply and cables as the problem. The signs of the impact are minimal except for a 1uf cap. It was bent and when looking at it closely, there is a...
  7. D

    DC MOTOR QUESTION

    I have 2 24v DC permanent magnet motors wired in parallel to 2 12v marine batteries wired in series. The motors are connected via gears to 2 axles which make up a truck for a 1/8 scale locomotive. I don't think the truck has equal force on each axle. (The frame of the locomotive is lower in...
  8. D

    Simple wiring problem

    I have a 250watt 12v landsape transformer powering lights, LEDs and accessories on my train layout. The total draw of all accessories is 5.57a. At the transformer, my volt meter shows 11.8 volts. At the end of my power wire, just before it connects to my terminal block it shows 11.8v...
  9. D

    Simple AC transformer question

    I have been using 12v 3a Radio Shack transformers and have recently found they are overloaded. So I'm looking for a good source for some with 100 watt (or so) output at a reasonable price. I've found low voltage landscape transformers, but they have timers. I don't want to pay for a case...
  10. D

    LED vs Incandescent

    I have a small project with a 6v battery power supply. In the project was 2 6v incandescent bulbs. I replaced one bulb with an LED and resistor. The bulb would no longer light. I understand electricity will follow the path of least resistance. Ok I have an LED nightlight in my...
  11. D

    LED vs Diodes

    It is my understanding a LED needs direct current to work. I have small LEDs which came from a 3v Walmart Christmas light string. I have a resistor in series and was going to put a small diode in series to protect the LED. I am using a 13v AC transformer. It doesn't make any...
  12. D

    Simple LED help please

    I'm about to my witts end on a simple project. I'm trying to install Radio Shack red blinking LEDs on my Lionel layout. They are rated at 20ma, 5 volts and I have a 13 volt AC power supply. From what I have learned, I need a 400ohm resistor and a DC power supply. Correct? Here...
Top