APA102C LED strip at 28 MHz clock

I recently received 1m of APA102C led strip with 144 leds per meter. I want to use the strip for rotary POV display so I cut the strip in half and tested the performance with a STM32L476RGT nucleo board. The results of the tests are surprising and very promising for my application.

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Battery with charger

There will be series of simple(r) circuits for my new electronic course for elementary school. For start we need power source. Batteries are fine until flattened out, therefore it’s good to have rechargeable one. I took MCP73831T-2ACI/OT, added micro USB connector and switch to select between charge/discharge mode. In the charge mode, the output is connected to +5V input supply. The power is delivered to the charger via micro USB connector, which means eny mobile phone USB supply will do the job. The charge current is limited to 2A and battery cell has integrated protection circuit. I will add 3D printed housing for the complete pack after the testing of first prototypes.

Prototype of the battery pack

Prototype of the battery pack

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Affordable pH meter

Our home vineyard delivers about 1000 liters of wine every year. It takes some effort to keep good quality and pleasure for all friends tasting the must, new wine and “senior” wine reserves. One of the most important tasks in wine quality management is controlling the biological and chemical state of the wine. The wine can be monitored in special laboratory or in home lab. Of course home lab become rational when quantity of the wine is high enough to justify expenses in special equipment.  There is some low cost equipment available for wine analysis, mostly with titration techniques, but chemical lab equipment is rather expensive and many hobby wineries avoid buying such equipment. I hope this post can contribute a bit to change that. I will describe the development of simple pH meter in detail.

IMG_6366.jpg    IMG_0855.jpg

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Electric penny board

Penny skateboards are available on every corner for something under 20€. They are a lot of fun to ride on and are very useful when someone has to travel a great distance in pedestrian only area. But what happens when a 2.5 kW electric motor is attached on it? Scroll down to find out.

 

 

Finished electric penny board

Finished electric penny board

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USB/RS485 converter on a double sided PCB

USB/RS485 module on a single sided board worked successfully for several months. The code is now stable and I decided to order small batch of double sided PCBs for this project. Here is documentation:

RS485/USB interface on a double sided board

RS485/USB interface on a double sided board

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LED shades

Light Emitting Dance shades – general purpose party accessory.

LED Shades v0.3

LED Shades v0.3

About this project

I believe many young adults like to party and with the rapidly growing EDM community a lot of people attend parties with electronic music. I am one of them and you can probably tell where I got the idea to make the LED shades. Projects like this one don’t just keep me occupied in my free time but are also designed to broaden my knowledge in electronics and programming. Continue reading ‘LED shades’ »

Having fun with kill-o-watts

Here is our new power supply having fun:

 

Soldering TQFN with a distance

The MCBs (Machined Circuit Boards – an alternative to DIY printed circuit boards) are now jumping out from the mini-CNC like in high volume production. This is new revision of RH/Temperature sensor with RS485 interface with Si7013:

New revision of Si7013 sensor module - machined boards

New revision of Si7013 sensor module – machined boards

The boards are solder “plated” and prepared for assembly process. However, there is one issue with Si7013. It comes in SMD housing without leads. This is no big trouble, but the thermal pad is, because there is trace routed under the Si7013, which is not GND:

The "problematic" trace is white hatched.

The “problematic” trace is white hatched.

That means it must not be soldered to thermal pad. The good thing is, the thermal pad can be left floating.

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PCB footprint for TAG-connect

This is altium PCB layout for TAGconnect TC2030-MCP-NL 6-Pin No-Legs Cable.

tag-connect

Tag-connect layout for connector without legs

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