I'm running a 6v smoke unit at about 5.3 v from my battery. I'd like to put an LED in the circuit to show when the smoke unit is actually turned on without dropping the voltage too much further.. The smoke unit runs off a positive and negative lead, through a servo controlled switch (powered seperately) and into the batterty. I'm looking for a suitable red or orange LED, the resistor (if needed) and instructions on fitting.

[link=http://www.lsdiodes.com/shop/index.php?main_page=index]LS Diodes[/link]

I've been buying from these guys. They've got different colors, shapes and sizes and a chart to tell you which resistor, if any you can use.

You can buy any basic LED and use a 1/4 watt resistor for current limiting. Since the voltage is about 5 volts use a 150 to 200 ohm resistor in series with the LED. Connect them in parallel with the smoke unit supply.

In other words solder the anode of the LED to the supply positive, one end of the resistor to the cathode of the LED, the other end of the resistor to ground. When the supply is on the LED will illuminate. You can use a higher value resistor to reduce the current if the LED appears to be too bright. This will also reduce power consumption.