my first mod

I just completed my first mod. I used a 1AA garity flashlight that was laying around. I couldn't wait to order some leds so I went into Radio Shack and bought a 10mm with 5000 mcd at 1.8v and 20ma. I tried it with a regular 1.5v alkaline and it was very dim. With a lithium AA it was much better. It didn't specify color but turned out to be red . I used a 6volt battery and 150 ohm resistor to get about 28 ma, and I was fairly well impressed. I don't care much for the red but I'll never get rid of it as it was my first mod. Now I need to order some nichias and try my hand on a solitaire, I would love to be able to do the satcure but I wouldn't know where/what parts to get. Quick question, how do you calculate resistance if you are using multiple leds? Thanks for the ideas and help.

Might check out this thread: http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=14&t=000247


I posted a link there to satcure and a useful link on resistors help.

Welcome to the world of torch modding...let me warn you, it's seriously addictive...my hobby, which has become a small torchmaking enterprise since, began with someone giving me a defunct rubber 2AA torch to modify to LED. It was modded by dissasembling the bulb and replacing it with an orangish red LED on direct drive... the magic of almoast evrlasting light sources got me hooked and here I am 20 or 30 torches later doing multiple LED mods and producing my very own torch, the EMPOWERTORCH BTx.
As to multiple LED's it depends on how you conect them as to the resistance required. LED's can be in series or parallel. If making a multi-LED PR Bulb drop in to save space inside the bulb base I will use a single resistor from the bulb cap tip and common all the LED anodes to it. The resistor value is worked out using the aforementionned formula for a single LED and then dividing the value obtained by the number of LED's in parallel.
Make sure that the resistor used is capable of taking the current.
In soe of my latest torrch creations I'm using mixed technologies to create a dual beam torch. The torch runs off a 4AAA supply producing 6V and I want to run 2 widebeam nichias (InGaN at 3.6V) and 2 narrow bbeam Toshibas (GaP at 1.9 to 2.3V).
The Nichia's each have thier own series resistor and are connected in parallel, but the Toshibas are connected in series with a single ballast resistor as thier forward voltages add up to less than 6V. This does mean that less energy is resisatored away in the form of heat and your torch produces more useful light!
I hope that the above information answers a few questions.
Happy torchmodding!

Here's a bunch of circuit stuff I've been collecting.

http://edusite10.tripod.com/led3/index.html

There's a schematic note in there that says dividing resistors are optional for multiple leds. They help divide current more evenly, but it seems to work just fine without them.