Hi there,
I'm working on my LED Flasher Array, using 20 Infrared LEDs (here's the datasheet for the ones I will be using: https://www.electro-tech-online.com/custompdfs/2004/12/QED233.pdf )
I've just got a few questions. I'm going to use Nigel Goodwin's PIC LED flasher (), and then just connect a transistor to one of the pins on the PIC, then connect LEDs in series to the transistor. Here's a crude drawing of what I want to achieve; P=PIC, T=Transistor, L=LED, R=Resistor and the dashes are wires.
P----T----R---L---L---L---L
So on and so forth. Leds will be blinking at 11hz. What I wanted to know is what transistor should I use for this? I used the MetkuMods LED calculator to calculate my resistance I should be using (http://metku.net/index.html?sect=view&n=1&path=mods/ledcalc/index_eng) but I wasn't sure that I was putting in the right numbers (Wasn't completely sure what Voltage Drop Across LED was), but if somebody could double check my work, that would be great. Here's the numbers I got:
.: LEDs in Parallel:
Supply Voltage: 12 Volts (since I'll be plugging it into a 12V socket in my car)
Voltage Drop Across LED: 1.5 Volts
Desired LED Current: 100 Milliamps
How many LEDs connected: 20
And that should give me a resistor of 5.6 Ohm that rates at 35 Watts... Does any of that look right?
If so, then it looks like I'll be needing a transistor that can take the relatively weak voltage from the PIC(+5V) and use that to switch on and off the 12V supply from the car. Let me know what you guys think, I appreciate it.
Thanks,
--mindctrl
I'm working on my LED Flasher Array, using 20 Infrared LEDs (here's the datasheet for the ones I will be using: https://www.electro-tech-online.com/custompdfs/2004/12/QED233.pdf )
I've just got a few questions. I'm going to use Nigel Goodwin's PIC LED flasher (), and then just connect a transistor to one of the pins on the PIC, then connect LEDs in series to the transistor. Here's a crude drawing of what I want to achieve; P=PIC, T=Transistor, L=LED, R=Resistor and the dashes are wires.
P----T----R---L---L---L---L
So on and so forth. Leds will be blinking at 11hz. What I wanted to know is what transistor should I use for this? I used the MetkuMods LED calculator to calculate my resistance I should be using (http://metku.net/index.html?sect=view&n=1&path=mods/ledcalc/index_eng) but I wasn't sure that I was putting in the right numbers (Wasn't completely sure what Voltage Drop Across LED was), but if somebody could double check my work, that would be great. Here's the numbers I got:
.: LEDs in Parallel:
Supply Voltage: 12 Volts (since I'll be plugging it into a 12V socket in my car)
Voltage Drop Across LED: 1.5 Volts
Desired LED Current: 100 Milliamps
How many LEDs connected: 20
And that should give me a resistor of 5.6 Ohm that rates at 35 Watts... Does any of that look right?
If so, then it looks like I'll be needing a transistor that can take the relatively weak voltage from the PIC(+5V) and use that to switch on and off the 12V supply from the car. Let me know what you guys think, I appreciate it.
Thanks,
--mindctrl