View Full Version : Resistors and fuses in parallel strings
hvacman250
04/26/2011, 07:42 PM
Is this correct?
V+ from driver--->1 amp fuse--->1 ohm, 3 W resistor--->to first led---series of LEDs--->V- of driver
To measure current, set meter to DC volts and measure the voltage drop across the 1 ohm resistor (one meter lead to V- and one meter lead at exit of 1 ohm resistor) ???
So a reading of 5.5A w/ a 1 ohm resistor woudl be 550 mA ?
unkel j
04/26/2011, 11:21 PM
Hooking up the meter accross a component like that on the voltage setting and reading the voltage drop is how you tell how many volts that component is using. If you want to measure current (amps) you would have to set the meter to the amperage setting and either use an inductive lead or break the circuit and hook up the meter in series so that all the current passes through the meter. Most meters can only handle up to 10 amps before they blow a fuse. If more than 10 amps are going to pass through the meter, thats when you would need the inductive lead. Does the circuit have an ac to dc transformer? If not, it should be ac and you would have to set the meter to the ac scale. As far as how to wire it, I could not say for sure but I have seen leds with a resistor at each bulb. You may have to go online and try to find a wiring schematic.
hvacman250
04/27/2011, 06:46 AM
This video on reefledlight.com shows them using resistors and measuring voltage drop across the resistor:
http://reefledlights.com/resistors-and-fuses-in-parallel-strings/
kcress
04/27/2011, 02:31 PM
Is this correct?
V+ from driver--->1 amp fuse--->1 ohm, 3 W resistor--->to first led---series of LEDs--->V- of driver
Yes. Perfect.
To measure current, set meter to DC volts and measure the voltage drop across the 1 ohm resistor (one meter lead to V- and one meter lead at exit of 1 ohm resistor) ???
Just measure across the resistor wherever it is. Use the meter set to DC volts. Preferably a low number like a 2V setting.
So a reading of 5.5A w/ a 1 ohm resistor woudl be 550 mA ?
No. If you measure 0.95V across your resistor that means 950mA is flowing thru your string. 0.654V => 654mA. 1.35V => 1.35A Etc, Etc..
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