The Ravemen PR1400 bike light ($70 as reviewed) is VERY bright in the HI / EMERGENCY mountain biking mode. Plenty of light. Blinding light. More than you should have on a road bike.

HIGH / Mountain Biking / EMERGENCY full power mode with both “high” and “low” beams at full power

Although it claims a 1.5 hour runtime in the highest setting, it actually goes for 1 hour 45 minutes in my testing, because it was producing so much heat the light would thermally throttle the light output and occasionally drop down to the “medium” setting until the light cooled down. [I was testing statically on a garage floor, so it may get more cooling airflow if you are actually riding it on a bike…]

High light setting in road biking (low beam) mode

The “road biking” modes deliver a more reasonable amount of light and it is aimed lower (think, low beam vs high beam). You get a High/Medium/Low/Eco mode in the road bike mode.

The eco mode claims to deliver 22 hours of battery life (I didn’t test this, but I believe it, as it is much dimmer than the high powered modes). I think this mode provides enough light to walk, or bike along at a walking pace, but I’d want to use the “low” mode at a minimum for most biking at night. There is also a “pulse” mode which appears to cycle between the medium and eco modes, and makes you more noticeable to drivers. Continue reading →

I recently tried out the DIYMalls DHT11 temperature and humidity (DHT11) sensors with an Arduino Uno. With simple 3 wire set up (+5 volts, ground, and data) and the Adafruit DHT library, it was super simple to get readings streaming over the serial monitor.

Example code is as follows:

// Must install Adafruit DHT library and unified sensor library.
// Code below borrows heavily from their example code, but distills it down to the bare minimum.
#include <DHT.h>

// Connect the yellow/Signal/data line to pin 4
// Connect the GND/black line to GND
// Connect the Red/VCC line to 5V

#define DHTPIN 4
#define DHTTYPE DHT11


DHT dht(DHTPIN, DHTTYPE);

void setup()
{
  Serial.begin(9600);
  Serial.println("DHT11 test!");
  dht.begin();
}

void loop()
{

// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
float h = dht.readHumidity();
// Read temperature as Fahrenheit (isFahrenheit = true)
float f = dht.readTemperature(true);

Serial.print(F("Humidity: "));
Serial.print(h);

Serial.print(F("% Temperature: "));
Serial.print(f);
Serial.println();

delay(2000);
}

This is the ELP-USB960P2CAM-V90, a dual camera with synchronized shutters on a single board. It streams side-by-side stereo pair images at maximum resolution of 2560 x 960 pixels [1280×960 for each image].  It is amazing what you can get for $80 on Amazon.   This module and a few hours of calibration and programming with OpenCV will get you a reasonable depth math / 3D vision setup.

It enumerated on my Linux system as a UVC 1.0 camera as follows:

usb 1-2: New USB device found, idVendor=32e4, idProduct=9750, bcdDevice=21.03
usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 1-2: Product: 3D USB Camera
usb 1-2: Manufacturer: 3D USB Camera
usb 1-2: Found UVC 1.00 device 3D USB Camera (32e4:9750)

Albert Armea walks you through the basics, including calibration using an older version of this module that was basically two different cameras on a USB hub (so they were not well synchronized and you had to open each camera independently) here:
https://albertarmea.com/post/opencv-stereo-camera/

For testing purposes, I didn’t even bother to calibrate the cameras, I just opened the stream, chopped it down the middle to get a left and right image, and passed that right into the SterioBM object.  sterio_camera_demo_code.zip