This might also be interesting for you: Do it yourself powerbank with voltage regulator and voltmeter

Planning and choice of material

Before I start building, I first think about where the solar panels should be mounted: One on the garden shed, two on the balcony railing and one on the weather station mast.

The garden shed has a straight wooden wall, which makes a flat bracket necessary. The balcony railing and the mast, on the other hand, each have a diameter of 30 mm – a bracket with a rounding is required here. So I currently need two different types of mounting.

I use a monocrystalline 2-watt module with an output voltage of around 6 V as the solar panel (see Figure 1.0.1). For the electrical connection to the panel, I opted for a standard 5.5×2.1 mm hollow socket (see Fig. 1.0.2). Cables and screws are not included in the illustration as they may vary depending on the application. The panels are available in packs of five or ten from various online retailers. Their dimensions are 120 × 110 mm (length × width), whereby the height can vary between 1.3 mm and 1.8 mm.

Construction of the housing

The central component for the solar panel mount is the frame. It provides both the stability and the sealing function of the housing. The frame must be torsion-resistant, be able to accommodate all the necessary threads and still remain compact. The solar panel is pressed into its seat from behind with strips so that it is tightly sealed at the front.
Several screws are required to create an even contact pressure (see Figure 2.0.1).

There is a cover on the back (Fig. 2.0.2), which is reinforced in an X shape for stability. This cover also accommodates the hollow bushing (5.5 × 2.1 mm), which is later attached with a small bridge. One of the four pressure bars that press the panel into the frame can be seen in Figure 2.0.3. The joint holder (Fig. 2.0.4) is used to attach the panel to railings or walls. This serves as a holder for the retaining lever, which holds the housing securely in place and allows flexible alignment.

Figure 2.1.1 shows the holding arm for railing attachment with a 30 mm diameter at the end. The counterpart for the holder can be seen in Fig. 2.1.2. The bridge (Fig. 2.1.3) for attaching the hollow bushing to the cover.

3D printing of the components

For 3D printing, I chose the following print orientations for the Prusa MK4 (see Figures 3.0.1 and 3.0.2).
Particularly important: The bar must of course be printed four times, as it is used on all four sides of the solar panel.

Thread cutting

Now let’s move on to my favorite activity: thread cutting. Admittedly, there is a lot to do in the frame (see Figure 3.1.1): The green markings indicate 12× M3 threads, the yellow ones 4× M3 threads.

There is an alternative version of the frame for those who are not the biggest fans of thread cutting. This is equipped with slots to accommodate normal M3 nuts. The matching file is called: Deckel110x120_V1-2.stl (see Figure 3.1.3).
The recesses for the nuts are also clearly visible in Figures 3.1.4 and 3.1.5.

On the back cover (Figure 3.1.2), however, the cutting of threads can hardly be avoided: 3× M3 threads and 2× M2 threads are required here.
Alternatively, self-tapping screws can also be used – this saves tools and time.

Soldering and assembly

Once all 3D printed parts have been cleaned and threaded, the solar panel can be connected and soldered.

Electrical connections

The first hurdle is to find out where the positive pole is located on the panel.
There are only two soldering lugs on the back of the solar panel, but no labeling – so: plus or minus? To determine this quickly and clearly, we need a multimeter. If we set it to measure direct voltage (DC), it helps us to recognize the polarity.

Figure 4.0.1: The red wire (positive) of the multimeter is connected to one of the soldering lugs, the black wire (negative) to the other. If a minus sign appears in front of the measured value on the display, this means that the red wire is connected to the negative terminal – i.e. the opposite tab is the positive terminal of the solar panel.

Figure 4.0.2 shows the reverse configuration: the red wire is connected to the positive pole of the panel, the black wire to the negative pole. In this case, no minus sign appears in the display – the polarity is correct,
and we now know for sure where the positive pole of the solar panel is.

The hollow socket is now soldered to the solar panel. Figure 4.1.1 clearly shows which connections need to be connected.
Figure 4.1.2 shows the finished soldering in the installed state.

I have also soldered a diode to the positive pole of the hollow socket (see Fig. 4.1.3).
This protects against reverse current: if the connected load does not have its own protective diode, the solar panel would draw energy from the battery in the dark – and unintentionally work as a heater.

A typical example:
If a charge controller does not have an integrated diode, the battery can discharge the panel backwards in the absence of sunlight.

The installation direction of the diode is crucial so that the current can only flow in one direction.

Mounting the hollow bushing and inserting the panel

The installation of the soldered hollow bushing on the retaining bridge is shown in Figure 4.2.1.
The hollow bushing is pushed into the large opening of the retaining bridge until the thread protrudes on the other side. The nut is then placed on the thread and tightened – the result is shown in Figure 4.2.2. The solar panel is now inserted into the retaining seat of the frame (see Figure 4.2.3, red frame).
If you want to increase the tightness, you can apply some elastic adhesive evenly to the seat before inserting the panel. Once the solar panel is correctly seated, the first strip is placed in position and lightly tightened with a screw in the middle (see Figure 4.2.4, magenta circle). A side view is shown in Figure 4.2.5 to illustrate this.

Fastening the slats and screwing

The remaining slats are attached one by one with the screw in the middle (see figure 4.3.1). Then insert the remaining screws, but do not tighten them yet (see figure 4.3.2). When the solar panel is evenly positioned, first tighten the middle screws of each strip.
Then tighten all the remaining screws and retighten them after a short time. If the solar panel still has some play, you can place some shims between the solar panel and the rail until it is firmly in place. Figure 4.3.3 shows how the hollow bushing and retaining bridge are attached to the inside of the back cover.
Finally, the back cover is screwed onto the frame with four screws (see Fig. 4.3.4).

Only a few steps are required to complete the bracket:
First, the M6 nut is pressed into the joint bracket (see figure 4.4.1).
The holder for the railing is then attached to the joint holder with an M6 screw (see Figure 4.4.2).
The joint holder is now screwed to the back cover with three M3 screws.
Do not forget: The M3 nuts must be pressed into the counterholder that will later be used for mounting on the railing (see figure 4.4.4).

Exploded view of the solar panel mount

For a better overview, there is an exploded view of the solar panel holder in Figure 4.5.1.

Note

Of course, there are also alternative mounting options. For instance, in a garden flower bed, plants may grow over time and gradually shade the solar panel. In this case, a holder with an aluminum rod and ground spike can be used (see Fig. 5.0.1).

On a balcony, the panel can be attached via flower boxes that cover the railing; here too, a holder with an aluminum rod is available (see Fig. 5.0.2).

Additionally, a holder designed for mounting on a wall or post is also provided (see Fig. 5.0.3).

Furthermore, I plan to design a solar panel holder with a built-in USB-C output.

The solar panel is an excellent addition for powering my small devices and outdoor sensors – and this holds true even in winter! Depending on your needs, you can either assemble the cables yourself or purchase them ready-made. In any case, the rule of thumb is: the shorter, the better.

Have fun building your own version – or perhaps this project has inspired you to create something entirely new.

Files for Download

• Housing for the solar panel mount

The post DIY solar panel mount for 2W panels appeared first on Nerd Corner.

You might also be interested in this: Hosting NestJS on Vercel

Creation of the Docker Compose Yml

With Docker Compose, all components of an application can be defined via a single configuration file and built or started together.

version: '3.8'

services:
  frontend:
    build: ./frontend
    ports:
      - "80:80"
    depends_on:
      - backend

  backend:
    build: ./backend
    ports:
      - "3000:3000"
    depends_on:
      - mysql
      - redis
    environment:
      - DATABASE_URL=mysql://user:password@mysql:3306/db
      - SESSION_STORE=redis://redis:6379

  mysql:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: root
      MYSQL_DATABASE: db
    ports:
      - "3306:3306"

  redis:
    image: redis:latest
    ports:
      - "6379:6379"

Creating the env file

To manage environment variables centrally, we create an .env file:

DATABASE_URL=mysql://user:password@mysql:3306/db 
SESSION_STORE=redis://redis:6379

Important: All ENV variables used in the code must also appear in docker-compose.yml!

Docker image for the frontend

The Angular frontend must be built for production. Here is an example Dockerfile:

FROM node:20 AS build
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm install
COPY . .
RUN npm run build --prod

FROM nginx:alpine
COPY --from=build /app/dist /usr/share/nginx/html
COPY nginx.conf /etc/nginx/nginx.conf

Since we are dependent on nginx for the build, we also need a corresponding config file:

server {
  listen 80;
  server_name _;

  location / {
    root /usr/share/nginx/html;
    index index.html;
    try_files $uri $uri/ /index.html;
  }
}

Docker image for the backend

The NestJS backend also needs to be built. Here is an optimized Dockerfile.

# Build stage
FROM node:20 AS build
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm install
COPY . .
RUN npm run build

# Production stage
FROM node:20-alpine
WORKDIR /app

COPY --from=build /app/dist ./dist
COPY package.json package-lock.json ./
RUN npm install --only=production
CMD ["node", "dist/main.js"]

Building the app with Docker Compose

Once all the Dockerfiles have been configured, the images can now be built. The whole thing is really easy with Docker compose.

docker compose up -d --build

The images are then ready, the containers are built and the app can be tested locally! The last step is to upload the images to DockerHub so that they can be used more easily later for deployment on a server.

Uploading to Docker Hub

Uploading is explained step by step below:

1. Create an account on Dockerhub
2. Create a repository for the frontend and backend (1 private repo is currently free)
3. Build the images and tag them:

   docker tag <image-id> dockerAccountName/frontend:latest
   docker tag <image-id> dockerAccountName/backend:latest

4. Sign up and push the images:

   docker login
   docker push dockerAccountName/frontend:latest
   docker push dockerAccountName/backend:latest

Outlook: Deployment with Kubernetes

Now that the images are on Docker Hub, nothing stands in the way of deployment. I have opted for a Kubernetes cluster on a Hetzner VPS. More information here.

The post Create Docker images and upload them to Docker Hub appeared first on Nerd Corner.

This might also be interesting for you: Do it yourself powerbank with voltage regulator and voltmeter

List of components

To demonstrate the function, I have decided on a small test setup. I need the following for my test setup:

• Barrel jack 5,5 x 2,1 (1.0.1)
• Voltmeter (1.0.2)
• 5V power supply unit (1.0.3)
• Barrel jack holder (1.0.4)
• Barrel jack Bridge(1.0.5)
• Some cables (1.0.6)

Assembly instructions for bracket and bridge

The first step is to print the holder (1.0.4) and the bridge (1.0.5) with the 3D printer. After cleaning the printed parts, I cut two M2 threads into the holder (see 2.0.1). If you prefer to work with self-tapping screws, you can skip this step. The barrel jack is then pushed into the large hole in the bridge (2.0.2) and screwed tight with the nut on the front of the bridge (2.0.3). Fitting the bridge to the bracket is also very simple: Slide the bridge with the recesses on the right and left over the two cylinder surfaces on the bracket (2.0.4) and secure it with M2 screws (2.0.5). The bracket and bridge with the barrel jack fitted form a very stable unit that can absorb large forces. If everything is fitted correctly, the barrel jack should not protrude, but should be recessed by 0.3 to 0.5 mm.

Wiring and soldering the barrel jack

Now we come to the core of this article: wiring and soldering the barrel jack. I use pre-assembled plugs and sockets that already contain crimped cables and a strain relief. The colour coding of the cables is also practical, as red stands for plus and black for minus (3.0.1).

The barrel jack with switching function usually has three solder lugs. The negative pole is always switched, i.e. in figure 3.0.2 this corresponds to number two. The negative pole of the primary power supply, e.g. battery or accumulator, is also soldered on here. Solder lug number one is intended for the common positive terminal; all positive connections are soldered here. The negative pole to the consumers in the device is soldered to soldering lug number three. Figure 3.0.3 shows the complete soldering of the barrel jack.

Assembly and connection

After successful soldering, you can now continue with the rest of the test setup. Firstly, the holder with the soldered barrel jack is screwed onto a wooden plate (4.0.1). The two mini-voltmeters are then attached to the wooden plate (4.0.2). The mini voltmeters are a creation of Nerd Corner. If you are interested in such housings, you can read the corresponding article and download the STL files at the following link.

Now I connect the cables soldered to the barrel jack to the mini-voltmeters (see Figure 4.0.2, pink frame). Next, I connect the primary power source to my 5V power supply and switch it on (see Figure 4.0.3, yellow frame). After switching on the power supply, a voltage is present at both mini voltmeters: 5.35 volts at the supply (red circle) and 5.28 volts at the load (green circle).

Integration of the second power source

As the current flows cleanly via the barrel jack to the consumer, the second power source now comes into play. I operate this with 12 V in order to have a clear difference to the primary power supply. Figure 4.1.1 shows the second power supply with 12.2 volts (turquoise frame).

Now I plug the second power supply with 12 volts into the barrel jack (Figure 4.1.2, blue frame). After a short delay, the value on the consumer’s mini-voltmeter changes to 12 volts (green frame). Nothing has changed on the primary power supply; it remains plugged in and switched on (red frame). The value is still 5.34 volts, which is 0.01 volts lower than before the second power supply was plugged in, but this is due to the fluctuations of the 5V power supply.

As a final step, I remove the 5 volt power supply unit from the primary circuit to check whether there really is no voltage on the primary circuit. Figure 4.2.1 in the yellow frame remains dark and so the test was successful!

Files for Downloading

• Barrel jack holder and bridge

The post Using a barrel jack as a switch appeared first on Nerd Corner.

My naive thought was that Tensorflow would automatically use the GPU. However, you first have to follow the step-by-step instructions below in order for Tensorflow to recognise and use the GPU at all.

You might also be interested in: Should I use Tensorflow.js or Tensorflow (Python)?

DISCLAIMER: As of version 2.11, Tensorflow no longer supports GPUs under Windows! Either change the operating system or downgrade Tensorflow to version 2.10. In addition, a graphics card from NVIDIA is required!

1. Checking the desired CUDA and cuDNN versions

First, you should find out which CUDA and cuDNN version you need for TensorFlow. The website lists all versions of Tensorflow and the desired CUDA versions or cuDNN versions: https://www.tensorflow.org/install/source_windows#gpu

2. Checking your own graphics card

As already mentioned in the disclaimer, the graphics card must be from NVIDIA. On the website https://developer.nvidia.com/cuda-gpus you can search for your own GPU and check the “Compute Capability”. The minimum requirement for Tensorflow is a value of 3.5, but this is fulfilled by all current graphics cards.

3. Installing the latest NVIDIA drivers

To enable the GPU for TensorFlow, the latest NVIDIA drivers must be installed. Simply go to the NVIDIA website and download the latest driver for your graphics card.

4. Install Visual Studio (optional)

In TensorFlow, some parts of the library have been written in C++ to maximise performance. Therefore, installing Visual Studio can help improve the compatibility and performance of TensorFlow: https://visualstudio.microsoft.com/de/vs/

It is sufficient to select individual components here. I have selected everything with C++ in “Compiler, Buildtools and Runtimes” and also MS Build, which in turn automatically installs a few more components. All in all, however, over 25 GB!

5. Install CUDA Toolkit

The CUDA Toolkit is a toolkit for CUDA application development provided by NVIDIA. TensorFlow requires CUDA to run on the GPU. Simply download and install the version of the CUDA toolkit requested in step 1 from the NVIDIA website: https://developer.nvidia.com/cuda-downloads

6. Installing the cuDNN libraries

cuDNN is a library of deep learning primitives provided by NVIDIA. TensorFlow also requires cuDNN to run on the GPU. cuDNN is free, but you have to create an account as NVIDIA Developer: https://developer.nvidia.com/rdp/cudnn-download

After the download, the content must be unpacked. The content is moved to the “NVIDIA GPU Computing Toolkit” in the “Programs” folder. After moving, copy the file path of the “bin” folder.

7. Set PATH variable

Open the environment variables by simply typing the term into the Windows search. Then edit the system variable “path” and add a new entry with the file path of the “bin” folder from the previous step.

8. Creating a virtual environment

It is recommended to install TensorFlow in a virtual environment to avoid conflicts with other Python packages. Ideally using Anaconda. Simply download and install here: https://www.anaconda.com/download

Then start the Anaconda Navigator. Create a new environment under Environments > Create. Then click on Home again and launch an existing Python IDE from here. Additional IDEs such as PyCharm should also be automatically displayed here after the download.

9. Verify Tensorflow GPU support

To check whether the TensorFlow GPU support was successfully detected, the Tensorflow package should first be installed in the Python IDE. But note that under Windows the GPU is only recognised up to version 2.10! In the following versions it is no longer recognised! Tensorflow 2.10 must therefore be installed.

Then run the following code to display a list of available GPUs:

import tensorflow as tf

tf.config.list_physical_devices('GPU')

The post Enable TensorFlow GPU under Windows appeared first on Nerd Corner.