FAQ
TL;DR: Most IR remotes modulate light at 38 kHz; “most consumer IR remotes use a 38 kHz carrier.” Build with a demodulating receiver, decode the protocol, then drive a relay or MCU. [Vishay, 2013]
Why it matters: This FAQ helps beginners wire, code, and secure simple IR remote circuits for switching lights, doors, or DIY home projects.
Quick Facts
- Typical carrier: 36–40 kHz; 38 kHz is most common in consumer gear. [Vishay, 2013]
- Typical indoor range: Approx. 5–10 m line‑of‑sight with a 940 nm LED and matched receiver. [Vishay, 2013]
- Popular IR protocols: NEC, RC‑5, Sony SIRC; data rates are often around 1–3 kbps. “IR remote control.” [Wikipedia]
- Uncoded receivers accept any remote; use coded or rolling code designs for security‑aware uses. [Elektroda, Mark Harrington, post #21667702]
How does an IR remote control circuit work?
A handheld remote blinks a 940 nm IR LED with data riding on a 38 kHz carrier. A demodulating receiver module filters, AGC‑amplifies, and demodulates that carrier to logic pulses. A decoder (IC or microcontroller) interprets the protocol and drives loads through a transistor or relay. “Most consumer IR remotes use a 38 kHz carrier,” so select a matching receiver. [Vishay, 2013]
Can I use this circuit to switch lights, doors, or other home loads?
Yes. A basic IR receiver can toggle relays to control bulbs, door strikes, or low‑voltage devices. However, if the receiver is uncoded, any remote using the same carrier may trigger it. “It will however work but is not secure by any means.” Add coding before using it for security‑aware control. [Elektroda, Mark Harrington, post #21667702]
Is a basic IR remote safe enough for home security?
It can work for hobby setups, but treat it as low security unless you add coding and tamper measures. One forum expert notes burglars focus on higher‑value targets; still, conceal sensors so the system’s nature is unclear. Use coded protocols and lockouts to reduce spoofing risk. [Elektroda, Frank Bushnell, post #21667705]
How do I add a coded output so only my remote works?
Use a microcontroller (e.g., PIC, AVR, Arduino) to decode a specific protocol like Sony SIRC or Philips RC‑5, and reject unknown frames. For stronger protection, implement challenge/response or rolling code. “Migrate to PIC micro and look at Sony IR in and Philips RC5 codecs.” [Elektroda, Mark Harrington, post #21667703]
What is Philips RC‑5?
RC‑5 is a bi‑phase (Manchester) encoded IR protocol defined by Philips. It typically uses a 36 kHz carrier with 14‑bit frames (toggle, address, command). It’s simple, well‑documented, and widely supported in hobby libraries and consumer devices. [“Philips RC‑5”]
What is Sony SIRC?
Sony SIRC is a pulse‑width encoded IR protocol family (12/15/20‑bit variants) commonly using a 40 kHz carrier. It defines address and command fields and repeats commands while a key is held. Many universal remotes and decoder libraries support SIRC. [“Sony SIRC”]
What’s rolling code and why is it more secure than fixed codes?
Rolling code changes the transmitted code every use, preventing simple replay attacks. Transmitter and receiver share a secret and a moving counter; only fresh codes authenticate. It’s the basis of systems like KEELOQ for remotes and access control. [Microchip, 2011]
How do I build a simple Arduino IR receiver and read remote codes?
- Connect a 38 kHz receiver (e.g., TSOP38238) to 5V, GND, and a digital pin through its OUT.
- Install the IRremote library; load the Receive example.
- Open Serial Monitor, press remote keys, note protocol and codes for your sketch logic.
Use a logic‑level MOSFET or relay module to switch loads. [Ken Shirriff, IRremote]
Why does my IR receiver misfire in sunlight or near CFL/LED lamps?
Strong ambient IR or lamp flicker can saturate the receiver’s AGC or mimic carrier bursts, causing false triggers or dropouts. Shield the sensor, use a proper 38 kHz module with narrow bandpass, and avoid direct sunlight. Some modules include improved AGC to resist interference. [Vishay, 2013]
What range should I expect, and how can I extend it?
Expect about 5–10 m indoors line‑of‑sight with a 940 nm LED and a matched 38 kHz receiver. Improve range by increasing LED current within datasheet limits, narrowing the LED beam, and ensuring clean line‑of‑sight. Use fresh batteries and proper carrier frequency matching. [Vishay, 2013]
Bluetooth or Wi‑Fi vs. IR: which is better for smart control?
IR is simple, cheap, and one‑way. Bluetooth and Wi‑Fi add encryption, two‑way feedback, and no line‑of‑sight requirement. For security‑aware control, consider BLE or Wi‑Fi and authenticated protocols. A forum expert suggested exploring Bluetooth and Wi‑Fi for modern systems. [Elektroda, Mark Harrington, post #21667703]
How should I place or hide sensors for home projects?
Mount receivers behind dark IR‑transparent windows, inside bezels, or near existing indicators. Avoid direct sunlight and reflective surfaces. Concealing sensor placement reduces tampering and keeps the system’s design unclear to casual attackers, as one poster advised. [Elektroda, Frank Bushnell, post #21667705]
What is RFID, and should I combine it with IR for access control?
RFID uses radio to identify tags without line‑of‑sight. You can pair RFID for identity and IR for command confirmation. If you use RFID, add encryption and an override method to handle card or reader failures, as highlighted in the forum discussion. [Elektroda, Mark Harrington, post #21667703]
Which receiver frequency should I choose?
Select a receiver tuned to your remote’s carrier, typically 38 kHz. Using the wrong center frequency reduces range and increases false triggers. Match 36, 38, or 40 kHz modules to your protocol and transmitter, with 38 kHz being the most common choice. [Vishay, 2013]
