DIY and Tinkering

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Currently I am preparing the bird nest cam. The ESP32 cam can be powered on two levels: On 3.3V or on 5V. In several articles on the web I found the information that the ESP32 Cam does sometimes not work properly when powered on 3.3V. Therefore I decided to power it on 5V. The LiPo cells of my old MacBook deliver 3.7V. So I needed a step up converter also called boost converter.

Summertime Project with the Kids: Soap Bubbles

Covid makes us still stay at home. Meanwhile we are allowed to leave home, but where shall we go? As the number of possible opportunities is limited, I had an idea of a nice little project with my kids: A soap bubble machine!

We took some parts of the Arduino starter kit and some Lego bricks and a few hours later it was finished.

Recycling old batteries

I found my 2007 MacBook in the attic and took it apart

MacBook 2007

I will try to re-use as many components as possible in my future projects, but first I’ll have to learn more about Apple’s components. I started with the battery. In its case are 6 LiPo cells. Unfortunately two of my cells are damaged, but that means 4 are left for further usage. Currently I am trying to charge them with the help of a TP4056 board and a 6V 200 mA solar panel. But to gather more data, I first needed to build a data logger.


The four remaining cells are in a good condition. It did several tests with them. I will use at least one of them as battery for my ESP32 cam.

Meanwhile I ordered a HDMI board at Amazon (LCD/HDMI-Karte für 12,1 Zoll / 33,8 cm B121EW03 V2 LTN121W3-L01 LTD133EX2X B133EW01 V4). With the help of this board I am able to use the display of my old MacBook as monitor of a Raspberry Pi4. I will build an Magic Mirror with those components.

Need something more complex…

The RC car project was nice. It showed me the principles of how to program in Arduino IDE and how to control engines. But I need something more complex…

My next projects will be either a small CNC machine or a smart LED lamp for my son. I know, DIY CNCs are as widely spread as my 4WD RC car project on the net, but most of them use existing libraries. I am thinking more on implementing my own protocol…

I also have many ideas for the lamp. First of all, I’d like to use an ESP32 controller, that would enable Bluetooth and Wifi usage. Then I am thinking about using Bluetooth audio, so I’d need an amplifier and speakers. Of course severals LEDs must be attached. The LEDs should be RGBs so color could be changed and brightness adapted. Maybe I’ll add a clock. I’ve not started yet because I still do not have a HMI concept: I was thinking about tipping on the light, but with all the audio, LED etc functions you can not use tipping. Then I was thinking about tough control. Yesterday I read an article about voice recognition which ws implemented on Arduino…. hmm. Let’s see where this leads me.

My First Arduino RC Car Atempt

The headline sounds pretty cool, but to be earnest: I messed it up. As this was my first real project with Arduino, it took my days to find out how things work and when I finally managed to drive the RC car I realized that I made several mistakes. Therefore I will not post what I did, but I’ll post what I will change in a few days.

The initial idea was to control a RC car via a Bluetooth module with my iPhone. Therefore I bought the HC-05 module which I already described in an article.

When I ordered the module, I did not know, that it is an Bluetooth 2.0 module and you need at least an Bluetooth 4.0 module to communicate with an IOS device. So, I ordered an HM-10 module, which arrived yesterday. The wiring is almost the same as the HC 05 and so my sketches for the HC 05 worked with the HM 10 too.

But I was not able to set up a connection between my Mac or iPhone and the HM 10. I googled the whole web and found that there are several articles out there pretending to be helpful, but they are not. Finally I tried the manufacturer’s site: Jinan Huamao Technology Co., Ltd.

Funny side fact: Nowadays you often hear people accusing Chinese companies to steal western intellectual property. I seems that Jinan Huamao does have a problem with other companies steeling their I.P. In the datasheet they wrote a paragraph on how to identify fake HM 10 modules.

They provide a package with very helpful files. But before I go into details, I’d like to emphasis, that I am not a professional and even more important: I do not have any knowledge about Bluetooth. What I write here is just what worked out for me. Do not hold me responsible if you follow my path and damage you hardware!

So, what did I do: The out of the box configuration of my HM 10 did not allow connecting my iPhone nor my Mac to it. Somewhere I found the info, that it is not as easy to connect a Mac to a BLE module as to a BT 2.0 module. I did not understand the reason, but the outcome it: If you’d like to connect to your Mac use the HC 05, if you’d like to connect to your iPhone use the HM 10.

I had to change the setup of HM 10. In the downloaded files there was a text file headlined „How to open ANCS function“. ANCS stands for Apple Notification Center Service. As far as I understood you use this if you’d like you bluetooth device to notify or to be notify on any change, like an incoming call, receiving a mail and so on. But I was not interested in using this service. To me it was more interesting to prepare my device for the service. I used the AT-sketch to change the set up:

  1. Send AT+TYPE3 command –> change to AUTH and BOND mode.
  2. Send AT+ANCS1 command to open ANCS.
  3. Send AT+PASS[para1] command to set passcode. Default passcode is „000000“
  4. Send AT+RESET to restart module.

I have not tried if step 2 really is necessary, but it worked. After I changed the setup my iPhone found a device named „HMSoft“ (the default name of HM 10).

Now I have a connection I can try if I am able to transceiver data. I will use Blynk as this seems to be a very convenient service – at least for starting. Because right now I am focusing on Arduino and not on programming apps.

HC 05: Wireless Bluetooth Transceiver Module for Arduino

In this Project I will try to bring my HC 05 Bluetooth module to life and control a LED with commands.

The HC 05: Wireless Bluetooth Transceiver Module for Arduino

But before I dive into the project, I need to write some words about the HC 05. It is a pretty old Serial Communication Bluetooth Module. It supports dynamic switching between Master and Slave mode – in contrast to its cheaper brother the HC 06. Both modules only support Bluetooth 2.x. That’s why it will not work with iOs devices – they need Bluetooth LE 4.0 support at least. I will buy a different module in the future. For the time being the HC 05 is ok for the first steps.

Don’t get me wrong. The Hc 05 is a cool module if you are using Android phones. They are not as picky as iPhones and i’ve seen cool projects in the web. But for iPhone users it is simply the wrong module.

But back to the facts: The HC 05 supports EDR (Enhanced Data Rate for tripple speed) on a 2,4-GHz band.

Pinning of HC 05

State: Do not know yet; I will post this asap

RX: Receive pin; DO NOT CONNECT TO 5V! If seen many projects on the web where the RX pin is connected to 5V, like one of Arduino’s digital pins. It will work, but it will harm the board. You should either use a Logic Level Shifter with 3.3V on one side and 5V on the other side. Or you use a simple voltage divider (see picture below).

TX: Transmit pin

GND: Connect with Arduino’s GND

VCC: +5V

EN: The enable pin for AT mode; must be high during powering the HC 05 to enter AT mode

Connecting the HC 05 using a voltage divider


Last friday I bought an Arduino. I did not know much about this thing, I ran across it when I visited some possible schools for our son. Some of the pupils showed what they did with it. And there were some really cool projects.

So I decided to buy one and find out where it will need me. I bought a Arduino Starter Kit which comes with multiple components like resistors, LEDs, switches and and and. But the most important thing ist the Project Book with 15 fun projects. The book really starts at the basics and leads you into the world of electronics and programming. Like!

It was at project 3 when I decided that the book is not enough. I needed a more sophisticated project in which I can include my son. So I decided to build robot car!

But with my current level of skills I will to be able to finish this project successfully. That’s why I will divide my project into several minor projects. First starting with a Bluetooth controlled LED. Let’s see where this leads…

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