gregc There is enough voltage for three 3.3V LEDs. I don't believe you need a bridge. Without it, the LEDs will only be forward biased half the time, so use half the resistor value. Some people will worry about the reverse voltage across the LEDs. I believe a normal diode can be used to protect the LEDs.
There is enough voltage for three 3.3V LEDs.
I don't believe you need a bridge. Without it, the LEDs will only be forward biased half the time, so use half the resistor value.
Some people will worry about the reverse voltage across the LEDs. I believe a normal diode can be used to protect the LEDs.
You really should use either the bridge rectifier or the single reverse voltage protection diode. LED's are diodes, but they are not design to withstand much reverse voltage and by not protecting them from that you risk greatly shortening their lives.
The bridge rectifier will give you steady lighting on DCC when it's combined with a capacitor. The circuit I use for the 12 v strip lighting segments and lots of examples can be found here: http://cs.trains.com/mrr/f/88/t/213765.aspx?page=2
Dave,
That circuit is very similar to the one I use. It should work for the 12 v strip lights, too, I'd think.
Mike Lehman
Urbana, IL
EDIT:
I decided to withdraw the circuit I had shown because CSX Robert pointed out that there was a risk of damage to the 5 volt capacitor should the LEDs fail. i.e. in other words, the cap might blow up.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
You will need a bridge rectifier to convert the AC power to DC for the LED. It will work with out the bridge rectifier but the lights will flash very fast.
Slim
greg - Philadelphia & Reading / Reading
Can a 3-LED string be powered by DCC track power through a bridge rectifier? Or is the rectifier not needed? It would require trucks with power pick ups.
RicZ