38khz led driver circuit

 · * Use an external Gated-Osc at 38KHz that the prop simply gates. A HEF should make a nice low-power, 38kHz 3 pin RC oscillator (3 pin has better tolerance than 2 pin), with 3v3 or even lower Vcc. If you can receive at 20Khz, you probably can also generate the modulation at the same speed, and just need a 38kHz gated-osc.  · The objective is to drive an IR LED at 38Khz off a 12F PIC. This will eventually be used in a infrared breakbeam circuit. I'm aiming at achieving a range of about 10m so I need the IR LED to be flashed as efficiently as possible. I'm just not sure if my circuit is the best way and if my component values are correct.  · The IR LEDs connected to the output emits IR pulses at www.doorway.ru circuit is ideal for most IR Sensors since these are designed for 38 kHz pulsed IR rays. The circuit uses IC uPD It is a CMOS version designed for IR www.doorway.rus: 1.

Really it is of no significance as long as the frequency is roughly 38KHz, and that you do not exceed the peak forward current in the datasheet. Better hardware will make it easier, but is by no means required. To get 38KHz you have to go up and down in 26uS, if you just set a period of 26uS then that gives you KHz. So that is a high period of 12uS and a low period of the same giving a total period of 26uS or 38KHz. There is no such thing as a "38KHz transmitter LED". There's no need for 2 transmitter LEDs to be dedicated to each frequency. That's just wasteful and you're missing out on possible distance gain.

The circuit here was designed to use a common IR LED and then amplify the tiny signal to drive an indicator. The range could be extended with subsequent. A common modulation scheme for IR communication is something called 38kHz modulation The second example circuit uses a nm IR LED and current limiting. LM Boost LED Driver Evaluation Board User's Guide (SNVA). Figure 1. Circuit Schematic. 2. Output Voltage. The forward voltage, VF, of each LED varies.