I love this topic there I like LED's in general and their applications.
In Auckland, New Zealand the first LED traffic light set appeared at the Auckland International Airport main road entrance around 2001.
In the last 2 years West Auckland has about ½ of all installations with LED's, some with only the high road lamps with LED's and side lamps with filaments.
The North shore and Central city are fitting the newer installations with LED's now a days but quite often only the high lamps.
You certainly notice the difference in brightness and equal colour and instant snap action during change over with almost a 'black stage' in between.
There is a batch (4) of Orange LED clusters out West with 4 LED's out, all in the same corner of the lamps. must be a manuf. error.
Some railway crossing lamps have LED's now and all the railway signal lamps at Britomart station are fitted with LED's.
We use LEDS in indicator lamps on the mains for the powerboard too, In kWh meters for potential indicators and streetlight and hotwater pilot circuits.
Very reliable LED indicator and better than the pre made ones I find is use:
High eff. LED, 2 x 33kOhm 1 Watt resistor in series, 1N4007 diode in series and 1N914 or eq. diode in antiparrallel with LED.
This yields a current of about 3 to 4 mA through the LED with very good visabilty and excellent lifespan >> 15 years in noisy, spikey electrical environment.
Note this is for 230 volts.
For 115 Volts 2 x 18 kOhms will do or a single 39 KOhms resistor.
I like to underrate the LED's a lot , most are designed for 20 to 30 mA and peaks of 100 mA are allowed. 4 mA is long life guarantied. LED man cheers
