Hi guys need your help if you can please im trying to wire some leds on to my buffer stop but woud like the power to come from track i hv on order 24 1.8 leds red plus resistor and dieo need to work out how to go from AC TO DC via the bit sais pics would be helful please ty inadvance .mike PS USING D C C ON LAYOUTl
Led problem
- Thread starter Why me
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Mike - since trackpower for dcc is on permanently, I'd have thought that taking a wire from one side of the track via a resistor to the led, and connecting the other leg to the other side of the track with another wire would solve the problem. I have a homemade signal on my DC layout that uses a two colour LED and protects an off-layout crossing. It shows red when the loco runs towards it, and green when it reverses. It is wired directly across the track and works fine. If you are running on AC you'll need a small bridge rectifier in the feed to the buffer stop
Shortliner(Jack)away up here in the Highlands
Shortliner(Jack)away up here in the Highlands
Mike,
Jack's suggestion of using rail power is a good one, no need to worry about AC. But if you do want to use AC, you don't really need a bridge rectifier to run an LED from AC power. It's better, but not necessary. I have done it many times and, because the LED is a diode anyway, it will run on AC and not be polarity sensitive. The LED will provide half-wave rectification which is all you need. If you are using AC accessory power, like 18 volts, use about a 3K ohm resistor in series with the LED. What happens is the diode blocks the current in one direction and gives you a DC pulse that is higher than the 18 volts, but the LED can handle it since it is on for only 50% of the time. That's OK since it happens 60 (or 50) times a second and you won't notice any flicker. If you do notice a flicker, than you can either go with a full-wave bridge like Jack suggested, or put a capacitor across the LED.
Jack's suggestion of using rail power is a good one, no need to worry about AC. But if you do want to use AC, you don't really need a bridge rectifier to run an LED from AC power. It's better, but not necessary. I have done it many times and, because the LED is a diode anyway, it will run on AC and not be polarity sensitive. The LED will provide half-wave rectification which is all you need. If you are using AC accessory power, like 18 volts, use about a 3K ohm resistor in series with the LED. What happens is the diode blocks the current in one direction and gives you a DC pulse that is higher than the 18 volts, but the LED can handle it since it is on for only 50% of the time. That's OK since it happens 60 (or 50) times a second and you won't notice any flicker. If you do notice a flicker, than you can either go with a full-wave bridge like Jack suggested, or put a capacitor across the LED.