Help with 5V Circuit & 3x 100 OHM Resistor LED

  • Thread starter Zatara7
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In summary, the person is seeking help with a circuit that includes a 5 V input, three 100Ω resistors in series, and one LED. They are unable to measure the current due to a broken fuse on their multimeter, but have tested the voltage and resistors and are using LEDs recommended for 300Ω at 5V. The issue was resolved by realizing a mistake in the breadboard setup.
  • #1
Zatara7
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Hello, I need help with this circuit. I didn't post this in the homework section because it isn't homework I'm just doing this for fun.
circuit:
http://imgur.com/i5fSX
image isn't working so here's a direct link: http://imgur.com/i5fSX

It is a 5 V input and three 100 OHM resistors in series and one LED. I can't measure current through it because fuse on multimeter died. I'm sure that 5 v is coming in because I tested that and the resistors are 100 +- 5 ohms I tested that too.
I have these leds (http://www.radioshack.com/product/index.jsp?productId=2062588) from radio shack and people on the website say that I need around 300 ohms at 5 volts to run turn them on but nothing.

I hope you guys could help out a circuit noob
 
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  • #2
You know you have 100Ω resistors, measure the voltage across the resistor, then calculate using:

[tex] I=\frac V R[/tex]
 
  • #3
Weird, I'm getting zero voltage across the resistor
 
  • #4
It looks like you are off by one hole in a couple of places. Rows of holes are connected, columns are not.
 
  • #5
the_emi_guy said:
It looks like you are off by one hole in a couple of places. Rows of holes are connected, columns are not.

Thanks a lot man. Yea this breadboard is different from the one we use in class. I was looking at everything else but it was just this simple fix.
after I measured the voltage now I'm getting 0.1667 like expected :)

thanks all for input
 

1. How do I calculate the voltage drop across each resistor in a series circuit?

The voltage drop across each resistor in a series circuit can be calculated by dividing the total voltage by the number of resistors. In this case, the voltage drop across each resistor would be 1.67 volts (5V / 3 = 1.67V).

2. What is the purpose of using a 100 OHM resistor in this circuit?

The 100 OHM resistor is used to limit the current flowing through the LED and prevent it from burning out. It also helps to ensure that the LED receives the appropriate amount of voltage for optimal functioning.

3. Can I use a different value resistor instead of 100 OHM?

Yes, you can use a different value resistor as long as it is within the appropriate range for the LED and circuit. The resistance value will affect the current and voltage in the circuit, so it is important to choose a value that is suitable for your specific needs.

4. How can I test the circuit to ensure it is working properly?

You can use a multimeter to test the voltage and current in the circuit. Make sure the voltage is within the expected range (in this case, around 5V) and the current is not too high or too low. You can also visually inspect the LED to see if it is lit up.

5. Is it safe to connect multiple LEDs in series with a 5V power supply?

Yes, it is generally safe to connect multiple LEDs in series with a 5V power supply as long as the total voltage does not exceed the supply voltage. However, it is important to use the appropriate resistors to limit the current and avoid damaging the LEDs or circuit.

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