Making a remote control or an infrared communication device requires a base system, which in this case would be an infrared emitter, combined with a specific circuit to achieve a high quality remote control, which we can use to manipulate a TV or a sound system. In this article, we will see how to make an infrared emitter in a straightforward manner.
- Four resistors: 1 of 22KΩ, 1 of 100Ω, 1 of 10KΩ and one of 100KΩ.
- Two transistors Q1 BC 548 and Q2 BC 557.
- 1 capacitor of 47 nF.
- An infrared type diode (LED).
- 5V power supply.
Creating our infrared emitter
In order to carry out our infrared emitterWe are going to make a series connection of our two transistors. First, we connect Q1 (BC548) to Q2 (BC 557), one of the outputs of Q1 goes to ground, while to the input of Q2 we will connect the power supply and the other contact will go to a branch that will be connected to a parallel arrangement with R2 and R3.
R3 will be connected to the capacitor in series and R2 to the LED, the other end of the LED will go to ground. On the other hand, we must connect at a junction point the output of the capacitor and the input on transistor Q1, from that point we will connect in series R1 and R4. The output of R4, will be a bifurcation where one side will go back to R4 and the other side will be connected directly to the other end of the power supply, in this way, we will have our infrared emitter (IR).
This basic emitter works in a simple way, the tone frequency of the emitter will be given by the capacitor. This frequency will be regulated by the 100K resistor, in this way, we will obtain our control signal.
An interesting point is that this base circuit can be modified to increase the power of this infrared emitter. To do this, we can connect two LEDs in series, and we even have the option of increasing the power supply with a power supply of up to 9V to compensate for the reduction of the resistor of 100.
Source: Electronics forums.