Range Finder LEDs

[animattor]

Is there anyone willing to share a schismatic of how to put together a small board with the LEds for the rangefinder. I really want to build it myself to keep my costs down but am unsure of the resistors needed. Thanks guys.

 

[Jc27]

You need to know the input voltage, the voltage of the LEDs as well as their current draw, to figure out what size resistors you will need.

 

[Jigglenomicon]

you can use this calculator to know how big of a a resistor you need
but only if the leds draw the same voltage and forward current
LED series parallel array wizard

For example i have 3 leds running in a parallel circut ,
Eatch draw 1.5 to 2v and their forward current is 20mA ,
so if i use a 9v battery i need a 150 ohms resistor.

Hope that helps a tad.

 

[animattor]

Thanks Jig that info was what was missing when we were at radio shack.

 

[Jigglenomicon]

eh.. doh i meant a serial circuit not parallel .
the calculator should work in both cases i think.

 

[Jigglenomicon]

also if you want some blinking red leds on top of the rangefinder you can get some that works without having a timer on your circut
[SIZE=-1]MSB557DA datasheet[/SIZE]