Sounds easy enough. Right? But I'm not getting the desired effect.
A simple circuit with a supply and an LED. See attached. (LED had range 3.2V - 3.8 V)
So here's what I have done.
Put a 3.4V supply across the circuit. LED shines. Supply unit tells me the current through the circuit is 51 mA.
So, I deduce that 51 mA makes my LED shine brightly.
Now, if I want to up the supply to 9V I need to create a voltage drop of 5.6 volts in the circuit between the supply and the LED.
I do my calculation using V = iR. ie: V = 5.6V, i = .051A. So R = 5.6/.051 Ohms = 110 Ohms.
So, I put my 110 Ohms in place and it has very little effect.
What am I doing wrong here?
Thanks
A simple circuit with a supply and an LED. See attached. (LED had range 3.2V - 3.8 V)
So here's what I have done.
Put a 3.4V supply across the circuit. LED shines. Supply unit tells me the current through the circuit is 51 mA.
So, I deduce that 51 mA makes my LED shine brightly.
Now, if I want to up the supply to 9V I need to create a voltage drop of 5.6 volts in the circuit between the supply and the LED.
I do my calculation using V = iR. ie: V = 5.6V, i = .051A. So R = 5.6/.051 Ohms = 110 Ohms.
So, I put my 110 Ohms in place and it has very little effect.
What am I doing wrong here?
Thanks
Attachments
-
135 KB Views: 20
Last edited: