HiLetgo 20pcs 5MM Photo Transistor Phototransistor PT334-6C Photo Transistor Phototransistor Round F5 3V

These work great. I make a voltage divider type circuit with these and a 10K resistor. I chose these over photoresistors for ambient light sensors for 2 reasons. The first is that since these are the shape of standard 5mm leds, they can be mounted in an enclosure using 5mm led holders which makes them easy to mount in enclosures. The second is that these are sensitive to a wide range of wavelengths from infrared to ultraviolet. Now ideally for an ambient light sensor, you only want to measure visible light, but I wanted to be able to use these on other projects like with infrared lasers, so I needed them to detect infrared too. When using touch screens in the car, the sun can hit at such an angle that it’s not really hitting the light sensor dead on, but is casting at an angle on the screen and washing the picture out. So I was hoping with the extra infrared light that the sun puts out compared to indoor lighting, that the arduino could overcompensate and increase the brightness.Overall these work well, mount cleanly, and have a wide range of sensitive wavelengths so these are great little sensors.

A photodiode generates a voltage even when not externally biased: if you just put the leads of a voltmeter on it and shine light on the device you will see a few tenths of a volt. It is like a miniature solar battery. Not so with these guys, which require a bias of a volt or so to put out a photocurrent. The attached I-V curve is typical of a photo transistor under illumination.Given that, the devices do work well as light sensors as long as you bias them. And the price is right!

I haven't tried testing for IR apps, but for visible white light these things are fine. Sharp curve means linear apps are going to be a PITA to get exactly right; would require either some calibration mechanism or automated gain control in the linear circuitry.

These were specifically purchased for an ESP32 laser tripwire project using a red laser diode and they worked perfectly.

Works well with 650 nm laser, and even with a blue-white LED with most emission around 450 nm.Was able to get 15-30 mV of perfect response range with a 650 nm red 5 mW laser.Excellent frequency response up to 20 KHz, did not test higher.Needs amplification to drive any load, but great for receiving optical signals.

These photo-transistors are working well for me in an application that involves measuring the intensity of visible light.

This is not a photodiode it is a phototransistor(it behaves like a light dependent resistor).If you want a photodiode just buy a regular LED.

Based on the information provided on the HiLetgo description the photo transistors are PT334-6C. Google this number for the datasheet.