Extending Infrared Remote Control Range
Numerous consumer electronic devices such as TV sets, VCRs, CDs, and DVD players are equipped with infrared remote control functionality. However, there are instances where expanding the control range becomes necessary. This circuit provides a solution by receiving the IR signal from your remote control and re-transmitting it, enabling control even around corners or in different rooms.
Photodiode Integration and Signal Conversion
The setup involves connecting photodiode D4 to the inverting input of a 741 op-amp through resistor R2 and capacitor C1. The BPW41 photodiode, sourced from Vishay/Telefunken, requires reverse-biasing to convert light energy into a corresponding voltage. To achieve this, it is linked to the positive supply rail via resistor R1, facilitating the necessary signal conversion process.
Setting Up the Signal Path
To maintain stability and accuracy, the non-inverting input of the ‘741 operational amplifier is held at half the supply voltage. This balancing act is achieved through equal resistors R3 and R4. Following the op-amp, a BD240 afterburner transistor is deployed, capable of delivering substantial current pulses through IR LEDs D2 and D3. However, it’s crucial to ensure that the pulsed current through the LD274s does not exceed approximately 100 mA. To regulate this, a fixed resistor is placed in series with preset P1. Additionally, a standard visible-light LED (D1) has been incorporated, serving as an indicator that flashes when an IR signal is received from the remote control.
When configuring P1, exercise caution not to set the IRED current higher than necessary for reliable signal transmission. Also, it’s vital to note that the mentioned currents are peak levels, given the small duty factor of IR pulses. Consequently, the average current drawn from the battery will be considerably smaller. For enhanced directivity of the IR LEDs — thereby extending the range of the control extender — reflective caps can be fitted to the devices.
Utilizing BPW41N PIN Photodiodes
BPW41N, a PIN photodiode enclosed in a black, side-view plastic package with a daylight-blocking filter, is employed in this setup. This photodiode boasts high speed and radiant sensitivity, particularly in the infrared spectrum between 900 nm to 950 nm. The filter’s bandwidth is meticulously matched with IR emitters falling within this range, ensuring optimal performance.
• High-speed detector for infrared radiation
• Infrared remote control and free air data transmission systems, e.g. in combination with TSALxxxx series IR emitters
- Package type: leaded
- Package form: side view
- Dimensions (in mm): 5 x 4 x 6.8
- Radiant sensitive area (in mm2): 7.5
- High radiant sensitivity
- Daylight blocking filter matched with 940 nm emitters
- Fast response times
- The angle of half sensitivity: ϕ= ± 65°
- Lead (Pb)-free component in accordance with RoHS 2002/95/EC and WEEE 2002/96/EC