Long Range/Distance Infrared Transmitter Circuit Diagram

Here's the long range/distance IR transmitter circuit , giving you extra power for the IR transmitter . Most IR remotes do the job reliably within 5 meters. The complexity of the circuit increases in case you design the IR transmitter to operate well over extended distances than, for example, 10 meters. To double the distance from 5 meters to 10 meters, it is recommended to increase the transmit power 4 times.

If you want to achieve a highly directional infrared beam with a very narrow beam, you can appropriately utilize an infrared laser pointer as an infrared signal source. Laser pointers are easily available in the market. Even so, with a laser pointer from a very narrow beam, you're going to need to take special care lest the little bastard gadget might change the beam positioning, causing loss of contact. Here's a really simple circuit that will provide a pretty long distance. It utilizes three infrared emitting LEDs (IR1 through IR3 series) to increase radiant power. Additionally, to improve directivity and power density, you can construct reflective infrared LEDs within the torch.

To improve the performance of the circuit, a MOSFET (BS170) has been applied, which operates as a switch thereby minimizing the power loss that would occur if a transistor was applied. To prevent any drops while in its "on"/"off" action, a 100µF reservoir capacitor C2 is used for the entire battery source. The benefits will be more obvious if the infrared transmitter is operated by common batteries. Capacitor C2 provides additional charge while the process "switches".

Since MOSFETs present large cross-gate-source capacitance terminals, a specific driver arrangement has been implemented for the NPN type PNP Darlington pair BC547 and BC557 (emitter follower) to prevent distortion of the gate drive input. The data being transmitted (CMOS compatible) is regulated using the CD4047 (IC1) at a frequency of 38 kHz. Even so, in the circuit shown here, tactile switch S1 has been utilized to modulate and emit an infrared signal.

Assemble the circuit on a standard PCB. Use switching power supply'/'off' S2 control. Commercially available infrared receiver modules (eg, TSOP1738) can be used for efficient reception of emitted infrared signals.