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TSOP-1738: How To Connect The IR Receiver In Circuits

Have you held a Remote Control and observed the infrared light via the LED when you press a button? The TSOP-1738 infrared sensor helps decode those output signals from your remote control. You find this IR receiver in home appliances like your Home Theater system, AC, TV, etc.

Furthermore, the TSOP-1738 IC is quite relevant in other fields of infrared technology. So if you have always wondered how IR receivers work, you are in the right place. 

The TSOP1738 Pin Configuration

This electronic chip functions as a switch. With its three pins, it is possible to connect the TSOP-1738 with devices such as microcontrollers, microprocessors, boards, etc.

TSOP1738 IR Receiver Features & Specifications

Here are some of the unique qualities of the TSOP-1738 IC.

  • The typical input operating voltage is +5V. However, a minimum input voltage of-0.3 and a max input voltage of 5V are tolerable.
  • The IC senses unique IR signals of 38kHz pulses.
  • At particular frequencies, the IC is fit to operate specific devices.
  • Although, the conventional operating current is 5mA.
  • Also, the TSOP-1738 has a low power consumption of 50mW when the max temperature is 85°C.
  • Further, it has relatively comprehensive coverage and a high range area.
  • In addition, the microchip can operate at a speed of 1200 bits/s.
  • The TSOP-1738 technology uses an internal filter for the bandpass to block ambient light. Therefore, it responds to IR pulses only.
  • The package comes with both the IR receiver and an in-built preamplifier.
  • It is compatible with both TTL and CMOS technologies.
  • There is an internal PCM frequency filter for releasing analog signals.
  • temperature range: -25 to 85°C.
  • However, the junction temperature inside is 100°C.

How Does the IR Receiver Work?

The TSOP-1738 IR receiver comprises several internal components. Together, they all contribute to how the IR receiver works. Below is a highlight of the major components and how they work.

A remote control icon showing transmission of IR signals

(A remote control icon showing transmission of IR signals).

Automatic Gain Control

In most cases, the IR receiver works directly without the AGC. However, the automatic gain control helps give the TSOP a more secure and intelligent functionality.

To that effect, you connect the IR receiver to the AGC. The Automatic Gain Control, in turn, acts as an input signal amplifier. Then it transfers these amplified signals from the IR receiver as output to the Bandpass filter.

Bandpass Filter

This component has several functions in the TSOP-1738. First, it receives and converts analog signals to digital form. In turn, the now digital output passes to the demodulator.

Furthermore, the bandpass filter and AGC combination are a good shield for familiar ambient light sources such as sunlight. Irrespective of the inbuilt sunlight protection feature, it is advisable not to use it from afar. As a result, other weather factors will have minimal effect on the TSOP transmission.

Lastly, the bandpass filter gives the TSOP a unique frequency of 38kHz for operation.


On one side, the demodulator has an NPN transistor connected. Meanwhile, the Bandpass filter connects on the other side.

So, when the bandpass filter outputs data, it goes in for demodulation. The demodulator, thus, acts as a low input signal driver for the NPN transistor.

Effectively, you connect the NPN transistor directly to the power, the collector’s output, and the ground of the emitter. As a result, the transistor turns off to detect low signals. On the hand, power then passes on to the output signal pin.

Control Circuit

In the TSOP-1738, the control circuit functions as a switch. For instance, output feedback from the bandpass filter switches on an output signal when there is output feedback. Therefore, this output signal at the output pin tells the AGC and demodulator that filtration is complete.

TSOP-1738 Equivalent IR Receivers

Other IR receivers are equivalent to the TSOP-1738. So, in a case where TSOP-1738 is not available, you have:

  • TSOP-17XX (a series of TSOP variants).
  • SM0038.
A robot controlled by a remote device

(A robot controlled by a remote device).

How to Connect the TSOP1738 Sensor?

Connecting the TSOP-1738 sensor for wireless communication is quite simple. However, the first step is to know how the supply voltage and IR signals work at the pinouts.

The three pins on the TSOP-1738 sensor IC are the ground, VSS, and output. Otherwise, you may find marks (-), (+), and OUT.

The pins marked (-) and (+) represent the supply terminals of the sensor IC. Usually, a supply voltage of 5V is the standard. But, you could still apply a voltage ranging from 3V to 6V. However, a 5V supply voltage is advisable for easy tuning with the 5V regulator IC 7805. In addition, it permits a wide input range of 6V to 24V.

On the other hand, the curved lens is the central focus of the sensor body. This lens is where you focus the infrared signal of the remote control device. In effect, the TSOP then begins to operate as a sensing device.


(A video guide on how to connect the TSOP-1738 IR sensor).

TSOP1738 IR Receiver applications

The TSOP-1738 IC is critical in several areas of modern technology. Below is an outline of the popular uses.

  • It works as a receiver for IR signals in TVs, doors, ACs, etc.
  • The IC helps build line-following devices like robots.
  • They are used in the analysis, recreation, and duplication of remote signals.
  • Generally, it is essential in applications requiring wireless control.
  • Furthermore, it is helpful in object detection technology alongside an IR transmitter.
  • The TSOP-1738 is also a component of tester circuits for IR remote control applications.
  • Most IoT security systems use the TSOP-1738 for a variety of applications. 
An example of a remote-controlled AC

(An example of a remote-controlled AC).


The TSOP-1738 is an IR receiver chip with an inbuilt amplifier. Most times, it functions as a switch. The IR receiver, at other times, works as a converter, depending on the circuit. Its input pins and output terminal help convert IR signals to electric signals. As a result, the TSOP-1738 is a valuable asset in applications like remote control systems, remote tester circuits, wireless control circuits, etc.

Building and fixing circuits is a gift to some and therefore comes easy to them. Still, some professional help with handling special devices like the TSOP-1738 IR receiver is advisable. So, feel free to contact us for assistance anytime.

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Emma Lu
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