bitem2k
New Member
To find the resistor in
hm: needed to protect a led i use the following equation:
R = (Supply Voltage - Led Voltage drop ) / I.
This seems to give an accurate value, so i use the next biggest resistor, about 50
hm: more. However when i measure the voltage drop over the led, it does not come even close to what i calculated. Nor does the current.
The multimeter appears to be working correctly, as it will measure accurately ( it agrees with my calculations) the voltage and current, in a simple voltage divider circuit.
Could these differences in calculated values be down to invalid specs given to me by supplier, or am i doing something wrong?
Also, if i know the current and resistance of a simple led and resistor circuit,
how can I find the voltage that runs through the LED?
thanks very much.![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
R = (Supply Voltage - Led Voltage drop ) / I.
This seems to give an accurate value, so i use the next biggest resistor, about 50
The multimeter appears to be working correctly, as it will measure accurately ( it agrees with my calculations) the voltage and current, in a simple voltage divider circuit.
Could these differences in calculated values be down to invalid specs given to me by supplier, or am i doing something wrong?
Also, if i know the current and resistance of a simple led and resistor circuit,
how can I find the voltage that runs through the LED?
thanks very much.