View Single Post
  #2  
Old 24th March 2019, 05:12 PM
bikerhifinut bikerhifinut is offline
Senior Member
 
Join Date: Jan 2006
Location: Penrith, Cumbria
Posts: 1,089
Default Re: KEL84 Bi-coloured LED

That's because its a red and green bi colour LED. Red plus Green = orange.
simply swaping the legs over only alters the sequence.
One LED is wired into the cathode circuit of one output Valve and the other (red) in the heater circuit. Thus as the amp warms up the colour changes from red to Orange as the valve begins to cunduct and volts appear on the green LED. In fact the colour should be closer to yellow than orange. Also as the voltages are different, 12V or so on the cathode and 6V or so on the heater then the dropper resistor for each leg is different and you would need to swap those over too, depending on where you made the switch of course.The fact that it started green and went orange suggests also that the LED had been reversed originally anyway so it looks like you have restored the default condition.
The idea is that if a fault occurs then the colour of the LED changes. It's of limited use really.
Referring to the build instructions and circuit diagram will show you this if you read them, assuming you built it yourself of course and obtained the full build CD.

Andy.
Reply With Quote