Component values question for simple LED path.

[tooki]

I have read the maximum current draw for an ESP8266 GPIO is 15ma. They are at 3.3V. So if you want a IR led with say a 50ma draw, you have to use a different sort of setup than a resistor and a LED.

Quick question, is that an IR LED for sending remote control commands? If so, you need to know that 50mA is way too little. Typical IR remote emitters are designed to be pulsed at 1-1.5A. The only reason they don’t burn up instantly is because of the low duty cycle. But those high currents is how you get decent range.

[wasedadoc]

Thanks maybe I'll go BJT with the gate resistor. Still don't know exactly how to enter the bjt transistor into the main resistor calculations. I am assuming the bjt gate resistor should be calculated as to produce like 10ma.

For future reference, a BJT does not have a gate, so mentioning "gate resistor" is incorrect.

[msuffidy]

Typical IR remote emitters are designed to be pulsed at 1-1.5A. The only reason they don’t burn up instantly is because of the low duty cycle. But those high currents is how you get decent range.

I was expecting 300ma, but I have no data on this specific IR led I harvested out of a cheap LED strip remote, so I played it safe at 50ma. Most remotes I have used have a range of about 25 feet. This one is about 10 which is not as good but not bad.

[RJSV]

   You've moved that LED back to being above the bjt, but by way of explanation, why; the reason LED on emitter is not so good is that your driver to the bjt base would then have to 'overcome' the LED voltage.
That is, the usual nominal 0.7 V when driving transistor has to have the LED drop added...so, if LED is, say 2.2V then that's 2.9 volts that your processor output needs to be.  That's marginal, but worse for the IR type, as the voltage requirement for the processor starts approaching RAIL or the max possible.
   When put on the collector, most designers don't even deal, much with the 'Vsat.' at nominal '002'...just assume LED connects to ground.
I think maybe high power circuits, like for driving audio speakers at high power (30 watts etc), those start needing consideration, the Vsat. on power output circuit transistors.
   2n2222 is also a nice NPN for LEDs.