Author Topic: Resistor?????  (Read 5911 times)

Offline cortay

  • *
  • Posts: 21
  • Karma: +0/-0
    • View Profile
on: September 19, 2008, 02:06:01 PM
Could someone please tell EXACTLY which resistor I should be using for the Vishay bulb??????  I am very frustrated right now. I thought I had put the correct numbers into the "resistor calculator" but I now believe they are wrong!  The vishay does not light up nearly as bright as the Radio Shack bulb I used without a resistor.  I am so confused!!!!!!!!!!!!  PLEASE HELP!!!!



Offline benpaddlejones

  • Support Admin
  • *
  • Posts: 1178
  • Karma: +49/-0
    • View Profile
    • Inter.Connect.Ed
Reply #1 on: September 19, 2008, 07:47:31 PM
cortay
Something must be wrong, this is not correct?

First go to http://www.dannyg.com/examples/res2/resistor.htm look at your resistor and plug in the colour bands, check you are using the resistor you think your using. Then I need the following info:

For calculating :-
   Power Source Volatge:
   Visay IR-led Model:

For Interest :-
   Power source size (N, AAA, etc):
   Power source type (Alkaline, NiCd, Nimh, etc):
   Power source brand:
   Rigging Wiring (hot glue, solder, mechanical, hand held):
   Wire Diameter:
   Resistor size using (ohms):

Benpaddlejones :)




See my full profile and links on my Google Profile: http://www.google.com/profiles/benpaddlejones


Offline cortay

  • *
  • Posts: 21
  • Karma: +0/-0
    • View Profile
Reply #2 on: September 19, 2008, 08:07:20 PM
PSV:  1.5V
Vishay TSAL 6400

Size "N"
Alkaline
Solder
1/8

I took out the resistor and it works WAY better.  Will this be ok?



Offline benpaddlejones

  • Support Admin
  • *
  • Posts: 1178
  • Karma: +49/-0
    • View Profile
    • Inter.Connect.Ed
Reply #3 on: September 19, 2008, 09:05:54 PM
Cortay
You should be using a 1/8w 1.5ohm resistor (Brown/Green/Gold/Gold).

If you are using the wrong resistor I suggest you use the correct one, as it will prolong the life of your IR-Led. You also may want to check the quality of your battery. Cheap batteries whilst saying 1.5v often are around 1.3v and have very quick drain rate. In this case a resistor is not needed.

Simply:
1. Make sure you have the correct resistor
2. If you are using a quality full powered battery, then yes use a resistor
3. If you plan to use low quality battery then no a resistor is not needed

Benpaddlejones :)



See my full profile and links on my Google Profile: http://www.google.com/profiles/benpaddlejones


Offline lderooy

  • *
  • Posts: 18
  • Karma: +0/-0
    • View Profile
Reply #4 on: September 30, 2008, 08:11:08 PM
Without going too much into the V=IR formulas, the resistor controls the current.  The current is somewhat proportional to the brightness of the LED.   

So if you have a big resistor the current will be lower and the brightness of the LED will be lower.  If you have a too small resistor (along with a higher voltage of 3 or more volts) then you could exceed the maximum current rating of the LED and "break" the LED.

 



Offline jamesKL

  • *
  • Posts: 83
  • Karma: +0/-0
    • View Profile
Reply #5 on: October 01, 2008, 09:37:14 PM
i dont think resisitor is required since the max forward current is 1.6v. it should be able to take it without any resistor