Out of stock
3DU33 Phototransistor - Smoke Detector
Silicon NPN Photo Transistor
Internal Reference:
SEN.3DU33
The 3DU33 is a small silicon NPN phototransistor mainly used for detecting infrared (IR) light and visible light.
It is a very common low-cost optoelectronic sensor used in:
- IR obstacle sensors
- Light detection circuits
- Line follower robots
- IR communication receivers
- Light barriers / object counters
- DIY Arduino projects
A typical package is a 5mm body, looking similar to a standard LED.
Main Specifications
Parameter | Typical Value |
|---|---|
| Type | Silicon NPN Phototransistor |
| Peak Sensitivity | ~880nm IR |
| Max Operating Voltage | 10V |
| Breakdown Voltage | 15V |
| Dark Current | ~0.3µA |
| Light Current | ~0.5–1mA |
| Package | 5mm Through-hole |
| Pins | 2 |
How it Works
A phototransistor works like a normal transistor, but instead of using base current, light controls the transistor conduction.
- More IR/light → more current flows
- Darkness → very small current
Usually connected with a pull-up resistor
When IR/light hits the sensor:
- transistor turns ON
- output voltage changes
Pinout
Most 3DU33 parts use:
- Long leg → Collector
- Short leg → Emitter
Common Applications
- IR flame sensors
- Encoder disks
- Robot line tracking
- Object counters
- Automatic lighting
- Optocoupler circuits
- RPM sensing
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