# Tagged Questions

601 views

### calculating resistance for LED strips to use as parking lamps and turn signals

I'm installing LED strips in my car's tail lamps to convert it from conventional bulbs to LEDs. I have a understanding of what I'm doing but not the complete knowledge to make the circuit work ...
99 views

### how many resistance do i need to safe the LED of PC814?

if i have a input of 5v (arduino HIGH) on the LED of a PC814, how is the value of the resistance that i must use before that, so i don't burn the led? ...
1k views

### Driving LEDs at long distance

I'm looking to drive 52 LEDs (datasheet), around a large inflatable tent. The LEDs have a forward voltage of 3.3V, at a maximum of 20mA. I'm thinking of using the NXP SAA1064 I²C 16-channel LED ...
806 views

### Requirement to display 3 mm LED by 220 V AC supply

I want to power a single 3 mm LED by a 220V AC source. For this I think I need one LED, one resistor and one capacitor. I don't know the needed resistor value and circuit diagram. The circuit also ...
4k views

### Connecting LEDs to a 9V battery

1) I have 6 4.5V 20mA LEDs and have connected them to a common 9V battery. Doing this I made 3 parallel circuits with 2 LEDs in each. Now, I see that most pages that describe LED circuitry say that ...
189 views

### wirewound adjustable resistor. Something I missed?

I am by no means an expert on electronics, but I thought that I had a fairly good grasp of the basics. That is, until 10 minutes ago. 1 picture ~ 1000 words, so here is what I have: The yellow wire ...
265 views

### What would the current be if I plug an LED into a perfect circuit

If I had an LED that had a forward voltage of 2.2 volts with a forward current of 20mA and I somehow created a battery that was exactly 2.2 volts and I put that LED, and only that LED, on that ...
3k views

### Correct formula for LED current-limiting resistor?

I'm trying to work out what value resistor to use in a LED circuit. The equation I'd use to do this is: $$R = \frac{V_{cc} - V_f}{I_f}$$ Seems logical, and makes complete sense. The answers to the ...