The TSOP1738 is an infrared receiver that helps electronic devices understand signals sent by a remote. It works at 38 kHz, which is the common frequency used in most remote controls. Inside the small package, it has everything needed to process signals, so it can give a clean digital output without extra parts. It is also built to handle light interference and uses very little power, which makes it useful in many types of electronic systems.
TSOP1738 IR Receiver Overview
The TSOP1738 IR Receiver is a highly reliable and used infrared detection module, designed for remote control systems and embedded electronics. Operating at a carrier frequency of 38 kHz, it ensures stable signal reception by filtering out unwanted ambient light and electrical noise.
Unlike basic photodiodes that require external amplifiers and demodulators, the TSOP1738 integrates a photodiode, pre-amplifier, automatic gain control (AGC), and a demodulator into a single compact package. This built-in signal processing capability provides a clean TTL-compatible digital output, making it easy to interface with popular microcontrollers such as Arduino, PIC, and Raspberry Pi. Its compact design, high sensitivity, and immunity to interference make it a preferred choice in TVs, set-top boxes, robotics, and other IR-based control systems.
TSOP1738 Main Features
Integrated Design
The TSOP1738 combines a photodiode, preamplifier, automatic gain control (AGC), and demodulator in one package, reducing the need for external circuitry.
Standard 38 kHz Frequency
Optimized for detecting IR signals modulated at 38 kHz, which is the most common standard for remote control systems.
TTL-Compatible Output
Provides a clean digital output signal that can directly interface with microcontrollers and digital logic circuits.
Noise and Interference Immunity
Built-in filters reject ambient light sources such as sunlight, fluorescent lamps, and other electrical noise.
Wide Operating Voltage
Operates reliably in the range of 2.7V to 5.5V, making it suitable for both 3.3V and 5V logic systems.
Low Power Consumption
Consumes minimal current during operation, best for battery-powered devices.
Compact Through-Hole Package
Available in a small epoxy through-hole design that allows easy PCB mounting and integration into compact electronic systems.
Long Detection Range
Capable of detecting IR signals from several meters away, depending on the transmitter power and environmental conditions.
TSOP1738 Pinout Diagram
The image shows the pinout diagram of the TSOP1738 infrared (IR) receiver module, a used component for detecting 38 kHz modulated IR signals from remote controls. It has three pins that are clearly marked and serve different purposes.
On the left side is the GND pin, which connects to the ground of the circuit and ensures stable operation. The middle pin is labeled Vs, and it is used to supply the operating voltage, typically 5 V DC. On the right side is the OUT pin, which provides the demodulated digital signal output. When the TSOP1738 detects a valid 38 kHz IR signal, this outputs switches between logic levels, making it easy to interface with microcontrollers or digital circuits.
Internal Block Diagram of TSOP1738
The diagram shows what happens inside the TSOP1738 infrared receiver. At the beginning, a photodiode (PIN) picks up infrared light signals. These signals are weak or change in strength, so they go through an Automatic Gain Control (AGC) stage, which keeps them steady. After that, the signal passes into a band-pass filter that only allows signals around 38 kHz, blocking unwanted noise.
The filtered signal is then sent to a demodulator, which removes the carrier frequency and leaves behind the useful digital information. A control circuit manages these stages to keep everything working smoothly. Finally, the output is sent to the OUT pin, while the other pins connect to power (Vs) and ground (GND). This setup allows the TSOP1738 to provide a clean, ready-to-use signal for electronic circuits.
TSOP1738 Electrical Specifications
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Supply Voltage (Vs) | 2.7–5.5 | V | 5V |
| Supply Current | 0.4–1.5 | mA | Very low power |
| Carrier Frequency | 38 | kHz | Center tuned |
| Output Voltage (Low) | ≤0.4 | V | At a 2 mA load |
| Output Voltage (High) | ≥4.5 | V | At Vs = 5 V |
| Reception Distance | Up to 5 | m | With standard remote |
| Viewing Angle | ±45 | ° | Half sensitivity |
| Operating Temperature | −25 to +85 | °C | Stable in most environments |
TSOP1738 Output Signal Characteristics
The image shows the output signal characteristics of the TSOP1738 infrared receiver. The graph plots voltage levels over time, demonstrating how the output reacts to incoming IR signals. The TSOP1738 has an active low output, meaning the signal goes LOW when it detects a valid infrared pulse and returns to HIGH when no signal is present.
This alternating HIGH and LOW pattern represent the demodulated data received from an infrared remote. The waveform makes it easy for microcontrollers and digital circuits to read the signal and process commands accurately.
Different TSOP1738 Applications
Television and Set-Top Boxes
Used for receiving signals from remote controls to change channels, adjust volume, and navigate menus.
DVD and Media Players
Provides reliable IR communication for controlling playback functions like play, pause, stop, and fast-forward.
Home Appliances
Integrated into air conditioners, projectors, and audio systems for remote-based operation.
Robotics and Automation
Enables wireless control in robotic projects, allowing movement, direction, and task management via IR remotes.
Arduino and DIY Projects
Popular among hobbyists for learning IR communication, building custom remotes, and designing smart control systems.
Security and Access Systems
Employed in IR-based door locks, alarm systems, and entry control where wireless activation is required.
Lighting Control Systems
Used in smart lighting solutions to remotely switch on/off or dim lights through IR remotes.
Toy Electronics
Commonly found in remote-controlled cars, drones, and other electronic toys that rely on IR-based control.
Connecting TSOP1738 to Arduino and Other Microcontrollers
Wiring Steps
• Connect Vs - 5V supply of the microcontroller
• Connect GND - Common ground
• Connect OUT - Digital input pin on the MCU
• Add a 10 kΩ pull-up resistor for signal stability in noisy environments
Programming Tips
On Arduino boards, the IRremote library is the most used option for decoding IR signals. This library supports popular IR protocols like NEC, Sony, and RC5, making it compatible with most consumer remotes. After installation, the received IR codes can be displayed in the Serial Monitor for quick verification.
TSOP1738 Placement and Performance Tips
• Face the IR source by mounting the TSOP1738 so its lens points directly toward the transmitter for reliable reception.
• Avoid strong light sources such as direct sunlight and fluorescent lighting, as these can saturate the sensor and reduce accuracy.
• Use a 100 nF capacitor across the Vcc and GND pins to stabilize power and reduce false triggering from supply noise.
• Add a dark IR filter window or tinted cover to block visible light and allow only infrared signals to pass through.
• Keep wiring short to minimize electromagnetic interference (EMI) and improve overall signal quality.
• Install the module in a stable housing to prevent vibration or misalignment during operation.
• Maintain line of sight between transmitter and receiver, avoiding obstacles in the signal path.
TSOP1738 Alternatives & Variants
| Model | Frequency | Package | Notes |
|---|---|---|---|
| TSOP1730 | 30 kHz | 3-pin TH | For 30 kHz remotes |
| TSOP1740 | 40 kHz | 3-pin TH | Common in AC remotes |
| TSOP1756 | 56 kHz | 3-pin TH | High-frequency remotes |
| TSOP38238 | 38 kHz | 3-pin SMT | Low power, compact |
| HS0038 | 38 kHz | 3-pin TH | Arduino-friendly equivalent |
Factors to Check in Purchasing TSOP1738
• Verify that the operating voltage is 5V to match your circuit.
• Confirm the modulation frequency is 38 kHz, as required by your remote system.
• Check the pinout and package type to ensure proper fit on your PCB or breadboard.
• Look at the sensitivity and detection range to match your application needs.
• Ensure the module has good noise immunity and AGC performance for stable operation.
• Review the operating temperature range to determine if it will be used in harsh environments.
• Make sure it is compatible with your microcontroller or development board.
Conclusion
The TSOP1738 is designed to provide stable and accurate infrared signal reception. It works well if it is connected properly and placed in the right direction. Adding simple steps like keeping the wires short, using a small capacitor for stable power, and avoiding strong light sources will help it perform better. With these considerations, the TSOP1738 can be used as a dependable part of many electronic projects and systems.
Frequently Asked Questions [FAQ]
What modulation does the TSOP1738 use?
It detects infrared signals modulated at 38 kHz only.
Can TSOP1738 work through walls or glass?
No, it requires line of sight, though weak reflections from glass or walls may work at short range.
Can TSOP1738 handle multiple remotes at once?
No, it can only decode one remote signal at a time; overlapping signals cause errors.
What type of output does TSOP1738 provide?
It gives an active-low digital output: idle is HIGH, detected signal is LOW.
Can TSOP1738 be used outdoors?
Yes, but sunlight and ambient IR reduce reliability unless filtered and paired with a strong IR transmitter.
What mistakes should be avoided with TSOP1738?
Don’t supply the wrong voltage, skip the 100 nF capacitor, expose it to direct light, or use long noisy wires.