I am planning on building a one of the circuits that were posted here - using a DF005 bridge, LM317LZ, cap and resistor. I plan to drive in parallel 5 leds, Do I need to have a resistor on each of the leds??? Thanks
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If you're driving five LED's in parallel, you'll want to consider the LM317T, I suspect you'll overheat the small TO-92 package with all of those in parallel. It's best to have a resistor for each LED, even if they're fairly small, say 50 ohms or so. This equalizes the voltages for the LED's and will result in even brightness. Without the resistors, one LED can hog more of the current and be brighter than the others or in the extreme case, cook. If you have enough voltage, you can also run the LED's in series.
Are you thinking of running the regulator as a constant current source? What are you putting this in, and what's the supply voltage you have?
Hi Gunrunner - I plan on installing this in a MTH pass car to replace the bulbs. We are talking about tmcc/Legacy so 18 - 19 volts AC in. This may have been a circuit you had designed / posted early in the year. Can't find the thread. Just trying to build something / rather then buy - Want to get my old EE legs back.
I'd use the LED strips, I posted about those recently in another thread. Check the 4th post of this thread, I just did some K-Line cars. I accommodated DCS with the choke, and I added a PTC to protect against cooking the wiring in a derailment. Total of five components for each car, it doesn't get much simpler than that. The connector detail was to show that I used snappable headers for the connectors, makes them cheap and small.
I lit the whole car with 20ma for all 18 LED's, and it's plenty bright.
Here's the thread: https://ogrforum.com/d...21#15086404566628721
If they are in parallel individually each LED needs a resistor.
Various circuits are shown on my blog
The lighting strips are circuited for 12VDC in and already have a resistor and are wired in series of 3
Dale H
That's basically the same as what I posted in the other thread. The only difference is I used the CL2 which is hard-wired to put out 20ma. Also, for command only operation, forget the bridge and just use a single diode, you'll get plenty of voltage and you don't have to drop as much power in the regulator. The bridge is good for conventional operation. If you run both conventional and command, use an LM317T in the circuit for the additional power handling capability.
If you want significant flicker resistance, try a 470uf 35V cap instead of the smaller one I used.
