DHT11 Temperature and Humidity (hydrometer) sensor – Example with source code for Arduino

DHT11 Temp/Humidity sensor attached to an Arduino Uno.
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);
}

ELP Synchronized Stereo Camera module (ELP-USB960P2CAM-V90)

ELP Bare circuit board camera module with dual cameras.

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

Dwarf Lab Dwarf 2 vs ZWO Seestar S50 Solar shootout

I took my Dwarf Lab Dwarf 2 and my ZWO Seestar S50 smart telescopes outside and imaged the sun.  Here is a 1:1 pixel side by side comparison of the results (click for full sized image):

Side by side shots of the sun by both the Seestar S50 and Dwarf 2 smart telescopes.

Unlike in the daytime lunar shootout, the Seestar automatically acquired the sun, giving it both the image quality and ease of use wins.    Here are the two videos showing my procedure and the GUI for each smart telescope’s phone app:

Dwarf Lab Dwarf 2 vs ZWO Seestar S50 DAYTIME lunar shootout

I took both of my smart telescopes outside this morning and shot some images of the moon in the daytime. I have a video that outlines the session (Dwarf2 won for user experience, SeeStar won for image quality) here:

Here they are side by size at 1:1 pixel size (click for full size):
Side by Side images of the moon shot in the day time by the ZWO Seestar S50 and Dwarf 2 telescopes.

And here are two of the raw images for you to look at as you would like:

Dwarf 2 image of the moon in daytime

Dwarf 2 image of the moon in daytime – click to see the raw/full sized image.

Seestar S50 image of the moon in the daytime

Seestar S50 image of the moon in the daytime – Click to see the raw/full image

Dwarf 2 Tips & Tricks

I’ve been using my DWARF II (Dwarf 2) smart telescope for a few months now and feel like I mostly know what I’m doing. Here are common questions I see on the user’s forum with my answers.

What’s the first thing I should do?

Remove the plastic film that protects both the cameras in shipping, the image quality is better that way. Then put it on to charge before nightfall.

Best first target?

If you are in the Northern Hemisphere, I recommend the M31 Andromeda Galaxy or M42 the Orion Nebula as your first “target”. (Use a phone app such as SkySafari or SkyView to confirm you have a clear view to your target first…the Dwarf app doesn’t really do a good job of letting you know what is currently visible in the sky.)

Both of these targets are relatively large and bright, so you should be able to image something even in city glow. Here is what my Dwarf was able to do all on it’s own, without any post processing (click image for full size):

Spiral galaxy Andromeda in a starfield

M31 Andromeda Galaxy, 198 stacked shots, 10 sec exposures, gain 40

astronomy photo of the M42 Orion Nebula in front of a star field

M42 Orion Nebula – 47 stacked shots, 15 second exposures, gain 50

Astro-mode Calibration

For plate solving / calibration to work, the DWARF needs to be able to see a good number of stars in sharp focus. You should check/set the telephoto settings (try 1 second exposure and a gain number that leaves the background still mostly dark, but shows stars well) and then make sure the stars are small dots [using the [+][-] focus buttons, and/or a Bahtinov mask if you like to be super precise….]

NOTE: You MUST remove all filters before using the calibration procedure, as it turns the Dwarf’s tube all the way to the “zeroed” position facing down, inside the body of the telescope, and the filter holder would prevent this motion.

Then, pick a “good” starting position. When the Dwarf does it’s calibration, it zero’s out the two axis (hitting the end stops) and then navigates back to ALMOST where you had it set up at. (the place you set it up at is image number 2, it takes one image 5-10 degrees to the left, and a 3rd image 5-10 degrees to the right. If all three images get enough stars to plate solve successfully, the calibration is done. However, if ANY of the images don’t work (trees, clouds, not enough stars) it will keep trying to take more images as it moves to the right (4,5,6,7,8, up to 9 total).
So, when you pick a starting position, make sure it has stars, and then scroll the dwarf to the left and the right to make sure both adjacent positions also have good views of stars. (Favor more stars to the right after that, as it never goes left more than 1 image from the starting position).
When it does it’s plate solving, you should see “streaks” of stars while it is moving, and at least one image with dots for stars for each of the 1,2,3 plate solving attempts. If you can’t see star streaks when moving or dots when shooting, the exposure time or gain or focus is wrong.
Also, very rarely I have had it “calibrate successfully” but STILL not have the right calibration (early in the evening when you don’t have many stars….it finds a solution that is under-constrained / wrong but still thinks it knows where it is….GOTO the moon or a known object to test to make sure the calibration worked correctly before depending upon it. [or at least watch the first few stacked images to make sure the object you are imaging actually appears in it before walking away…]

 

Telephoto aiming rectangle mis-calibration

Because the telephoto lens and the wide angle lens are separated by 4 inches (have parallax) the area inside the rectangle in the wide angle view may or may not correspond to the field of view of the telephoto lens, depending upon the distance to your target.

To fix this, have the wide angle lens view be large (with the telephoto view in the smaller picture-in-picture mode). Then, you can press and hold your finger on the rectangle, and drag to move it around the wide angle view.  [I suggest you use the joystick to aim the telephoto view at something that is distinctive in the wide angle view, such as the top of a utility post, or recognizable star.]

This calibration should be “good” for objects of the same distance, but if you calibrate it with a close up object, it won’t match up for “infinite” field of view objects like stars.

MicroSD card “upside-down” orientation

The micro-sd card orientation is “upside down” from what you might expect it to be. Pay very special attention to the icon of the SD card and which way the small cutout on the card is facing when you insert it.

Rubber Micro SD card cover not fitting

If you pull out the rubber cover for the Micro SD card, you will find that it is attached to the Dwarf 2 with a thin cylindrical piece of rubber (attachment string) that comes out of a hole.  If you pull it out too hard, the cylindrical rubber bit may not want to go back into the hole, and the rubber plug may not re-insert correctly, which will block the rotation of the telescope tube when the Dwarf tries to calibrate.  To fix this, you have to carefully push the cylinder of rubber back into the hole, either by using a pair of tweezers, or by carefully pushing using the rubber plug near the cylinder. Some careful maneuvering should get it to slide back into the hole.  Once the cylinder is sliding freely back into the hole, you will be able to re-insert the micro SD card cover.

Polar or Equatorial or EQ alignment

The Dwarf 2 is designed to be mounted on the level, and its two motors act as an Altitude / Azimuth  (Alt/Az or pan/tilt) head. [The entire telescope rotates around the small base to provide Azimuth control, and the telescope tube rotates to provide Altitude control.]

It works fine in this configuration, and it uses it’s alt/az drive to track the current object of interest. But if you are taking a large number of images, due to the rotation of the Earth, the subsequent images are slightly rotated from the first image, even if the target stays in the center of the frame. This is called “Frame Rotation” and results in not having a full set of images for the outside edges of your image stack. [And requires any software stacking solution to apply a corresponding “anti-rotation”.]

You can mostly resolve this issue by mounting the Dwarf2 telescope with the axis of the base (azimuth axis) pointing in the same direction as the Earth’s axis of rotation. In the northern hemisphere, the easy way to do this is to align the Dwarf 2 with Polaris (the north star). This can be done with a tripod head that tilts at least the number of degrees of latitude of your location.  [There are several 3D printed aiming devices to help you, or you can just tape a drinking straw to the side of the Dwarf.]  If you want to know how to do this, I recommend this video: https://www.youtube.com/watch?v=X9rIk6skTU8

The questions are then….but will the DWARF work correctly in this “non-level” configuration? Will this hurt my Dwarf, or void the warranty?

Many people, including myself, are using the DWARF 2 in polar alignment successfully, so it does work and helps to reduce field rotation. So far I have not heard of any reports of a DWARF 2 failing because it was used in polar alignment, or of DwarfLabs denying a valid warranty claim due to usage in polar alignment.

However, you should know that early models of the DWARF 2 had an issue where the base plate could break off of the base. As the base plate is where the tripod nut is mounted, this could cause the entire rest of the telescope to fall to its doom.  [Dwarf Labs has published a technical note explaining how to fix this yourself if you have one of the early models.] This is due to a design flaw (the plastic that the base plate screwed into was not strong enough for the potential forces).  The factory has “fixed” this issue by using a glue to adhere the base plate to the bottom of the Dwarf as part of the assembly process.  However, I am still suspicious of the overall strength of the tripod nut and base plate, so I use a 3D printed “support bracket” with my Dwarf. It is called the “Dwarf 2 Base Plate Saver“. With this bracket, which distributes the load around the entire base of the Dwarf, I do not worry about mounting it in polar alignment.

The azimuth motor has worked perfectly fine for me, even with my Dwarf at a 28.5 degree tilt. As the weight is nicely balanced, I expect it would work very well, even with the dwarf at a much more inclined angle, so motor strength does not appear to be an issue.   There is a potential issue of the axis bearings not being designed for off-level operation, but so far I have not noticed any issues that I can attribute to non-level mounting.

Post Processing Software for Linux

If you want to spend money and get the best result, Pix Insight  (and related plugins that cost more money) is the way to go. (There are a few other paid software that only work on Windows, but at least Pix Insight is cross platform.)

I have not spent any money, and am using the Open Source SIRIL software instead.
There are a lot of videos about how to use SIRIL on YouTube…but this one is Dwarf 2 specific and also shows off Pix Insight.

Both pieces of software have a steep learning curve, but post-processing off of the DWARF can improve your final result significantly.  For example, here are my results post-processing data from the two example images above using SIRIL (click for full size):

 

Anova Precision Handheld Vacuum Sealer – Works with FoodSaver Jar sealer accessories

Anova handheld vacuum sealer on top of a foodsaver jar sealer

We have a FoodSaver vacuum sealer that we only use for the accessory port with the mason / canning jar lid sealer accessories. [These allow you to vacuum seal items inside a canning jar.]

I purchased an Anova handheld vacuum sealer (that is made to work with re-usable ziplock style vacuum bags) and verified that it fits well enough onto the top of the FoodSaver jar sealer accessories to vacuum seal jars without the use of the (rather large FoodSaver).  This will allow me to get rid of the foodsaver, and only store the mason jar lid accessories with the Anova handheld vacuum pump.

I confirmed that the Anova unit could pull 14 inHg on the initial vacuum, and if you pushed the button a second time, it would get the vacuum down to 15 inHg. [The plug-in full sized FoodSaver unit drew down to 16 inHg, so slightly more vacuum, but not enough more to justify the space it takes up.]

 

 

Amazon affiliate links:

VECY’s CR60 car Fridge / Freezer (Dual Zone) Review

VECY's CR60 fridge

I reviewed the VECY’s CR60 car refrigerator / freezer. It is a 60 L wheeled cooler with built in dual zone compressor heat pump.  It has a dual zone control panel that can maintain temperatures between 68F down to -4F, and is powered by 12-24 volts DC. (It also includes an AC adapter to power it from 120-240v AC.)

You can watch my 5 minute summary review here:

(I also have a 30 minute long full review…but unless you are REALLY interested…the summary review gives you all you need to know.)

If you would prefer to read your review, here are the relevant details:

 

Continue reading

Battery Tray / Door discoloration on First Alert Smoke Detector (2018, SA511)

When changing smoke detector batteries on my First Alert SA511 smoke detectors, I noticed that ONE (of the six) has a discolored battery tray/door. It appears that the plastic used to make the battery tray was of a different composition from the rest of the shell, as it has turned yellow with age, while the rest of the smoke detector has not. (Also, my other five smoke detectors all have pure white battery trays that match the body as well…) Continue reading

ezShare (ez Sh@are) Wi-Fi SD Card – Works with Linux (and any WiFi enabled device with a web browser)!

32 GB ez Share Wifi SD card

A while back I purchased a generic Wifi Micro-SD card adapter that didn’t work with my Linux computer due to the proprietary protocol it used.  This ez Sh@are 32GB SDHC +Wi-Fi card is what I should have purchased in the first place.

When powered in the camera, it acts as an AP and broadcasts a Wi-Fi network (default SDID: ez Share, default PW: 88888888  – eight eights) that you can connect to with any laptop or phone. It captures your browser and directs it to a “ezshare.card” web-server that displays the photos on your SD card. (If that doesn’t work, you can direct your browser directly to 192.168.4.1).

You can view thumbnail previews of the images, and download a single image, or a selection of images (as a tar file) or all images in the folder (again, as a tar file).

If you want to see or download videos on the card, you need to select the “Video Gallary” link (it doesn’t show previews of the videos).

The only configuration options are to change the SSID of the network, the WiFi network password, and the administrative password (the default admin password is “admin”).  You should change the wifi password and the admin password if you don’t want random people downloading the photos from your SD card anytime your camera is on.

If you mess up the configuration, or find a ezShare WiFi card that you can’t access, the configuration is stored in a file on the card, so if you format the card it will overwrite the configuration and go back to the defaults.

I bought the 32GB card that includes a “share” (or not) switch on the bottom that gives you the option to turn off the WiFi AP when you don’t want to export one (Airplane mode, or to save power).  You can also purchase a TF/MicroSD card “adapter” version, that includes the WiFi server, but does NOT include any memory, allowing you to insert a larger sized MicroSD card if you need more than 32 GB of storage.