App note: HV823 & HV825 EL lamp driver circuits


App note from Microchip on their EL lamp drivers circuits utilizing (Supertex) HV823 and HV825, App note here.

This application note presents fourteen EL driver circuits utilizing the Supertex HV823 and HV825 drivers. They have been optimized for a variety of applications and may be used as-is or used as a starting point in designing a circuit for a particular application.

App note: HV823 & HV825 EL lamp driver circuits – [Link]

EEVblog #761 – Pebble Time Smartwatch Teardown

What’s inside the new Pebble Time Smartwatch?
Dave does a teardown after taking it through the torture test, and gives it a close up view with the Tagarno microscope.
How easy is it to disassemble and replace the battery?
How much do the components cost?
What is the manufacturing quality like?
How does the Bluetooth antenna work?

EEVblog #761 – Pebble Time Smartwatch Teardown – [Link]

Arduino Stepper Motors


by cornelam @

When we need precision and repeatability, a stepper motor is always the solution. With the way it is designed, a stepper can only move from one step to the next and fix in that position. A typical motor has 200 steps per revolution; if we tell the motor to go 100 steps in one direction, it will turn exactly 180 degrees. It gets interesting when we only tell it to go one step and it turns exactly 1.8 degrees.

Arduino Stepper Motors – [Link]

Arduino VFD Display Clock Tutorial


by Kesselwagen @

Vacuum fluorescent displays look really kinda fancy and cool to me, I really love the blue-breen color. That’s why I decided to write this Instructable about a clock based on this technology. This is my first instructable here, showing you how I have designed built my clock and how you can build yourself exactly the same or a similar clock that utilizes the VFD display. I’m not a native speaker – just for you to know if you’re wondering why some sentences might make no sense at all.

Arduino VFD Display Clock Tutorial – [Link]

Tiny-Dice: Electronic Dice Using an ATtiny2313


by Florian Schäffer:

This simple electronic dice is an ideal starter project to introduce youngsters and those still young at heart to the dark arts of microcontrollers and circuit building. We take you step by step through the process. For your troubles you will build a useful electronic dice. It will put an end to you scrabbling around under the table to retrieve a dice that’s been carelessly tossed and also an end to cheating… It landed on a six! It really did… yeah right.

This simple circuit simulates the rolling of a dice (or ‘die’ to pedants). When the roll button is pressed the display shows random numbers in the range of one to six, after a while the display settles with one number on the LED display.

Tiny-Dice: Electronic Dice Using an ATtiny2313 – [Link]

Add a fuse where it´s desirable


Without problems and directly at connecting a device. How? With a new Euroclamp MPF03 terminal block with integrated fuse holder.

Nowadays, when “almost everything” works on electricity we can see still more devices connected to mains line. That´s why it often happens, that many small-power devices are connected to one (circuit breaker fused) line. To increase a safety, it´s usually advantageous to fuse particular devices separately – for example by small glass fuses. Somewhere it´s advantageous on a panel or directly on a PCB, elsewhere directly in a control relay interface module and in many cases directly in a place of connection.

For this purpose a novelty in our offer is very suitable – 3-pole terminal block MPF03-10, where one of poles is fused by a glass tube fuse 5x20mm. In praxis it can look so, that on a place where you so far used a classic (“chocolate”) terminal block, you can use MPF03 and insert a suitable fuse.

In the MPF series can be found series with 1-5 poles. As already a name says, pin spacing (pitch) of the MPF series is 10mm. On stock we have the 3-pole version MPF03-10 ideally suitable for mains line appliances (L,N,PE). Exact dimensions and further parameters can be found in the Euroclamp MPF03-10 datasheet.

Add a fuse where it´s desirable – [Link]

Cliff knobs – a pleasure to touch


In our portfolio can be found quality knobs from company Cliff suitable for a wide range of potentiometers and encoders.

A device with excellent specification, quality components used, …., but a one step is still missing to reach a great overall impression – it is to use a quality and aesthetic control components.

Probably you´ll agree, that knobs for potentiometers and encoders belong to a “group of critical components”, determining a resulting look of a device. Company Cliff specializes on development and production of these components already from 1977 and considerable experience are reflected in a precise construction and a wide portfolio of components produced.

Directly from our stock, we´re able to offer you a few interesting series:

  • K87MAR – plastic two-color knob with a colored top part and a side line. Available in 8 standard color versions. Thanks to a big popularity and a mass production, their price is very affordable. User friendly, soft – “rubber-feel” surface. Excellent for color coding of potentiometers groups in equipment with many knobs. 6mm „D“ shaft.
  • K87MBR – plastic two-color knob, very similar to series K87MAR, but only a side line is in color. Affordable price and a mild “rubber-feel” surface. 6mm splined shaft or 6 mm “D” shaft.
  • K18 – universal plastic knob for electronic encoders. Available in 5 colors and 3 weight categories. In our stock can be found 2 heavier versions (35 and 50g) in a grey and black color.
  • KMK – universal aluminium knob with a machined aluminium shell and a molded plastic inner. Available in a black or natural anodized surface. Push-on installation. In our stock can be found 4 versions with a 25 mm diameter – KMK25 in a black and silver (natural) color, with a 6mm splined as well as “D” shaft.

Types for splined arbors have 3 relatively robust juts (as visible on a Picture), that´s why they´re suitable only for potentiometers with deeper splines, or with a lower splin count. From our offer they´re suitable for example for Taiwan-Alpha potentiometers and they´re not suitable for potentiometers Piher series PC16.

Further information will provide you the K87MAR, K87MBR, K18 and KMK datasheets. Upon request, we´re able to deliver you more types from the portfolio of Cliff knobs.

Cliff knobs – a pleasure to touch – [Link]

Basic Temperature Control for Refrigerators

This design is a basic temperature control for refrigerators that has an electromechanical circuit. It specifically uses MC9RS08KA4CWJR microcontroller which has an 8-bit RS08 central processing unit, 254 bytes RAM, 8Kbytes flash, two 8-bit modulo timers, 2-channel 16-bit Timer/PWM, inter-integrated circuit BUS module, keyboard interrupt, and analog comparator. This project effectively controls temperature of any device using resistors and capacitors.

The refrigerator temperature control is a basic RC network connected to an I/O pin. A variable resistor (potentiometer) is used to modify the time the capacitor takes to reach VIH and adjusting its resistance varies that time. A basic voltage divider with one resistor and one thermistor is used to implement the temperature sensor. The thermistor resistance depends on the temperature. For each temperature, we have a different voltage in the divider. This value is effectively measured with the Analog-to-Digital Converter (ADC) implemented by software that uses one resistor, one capacitor, and the analog comparator. In addition, VDD and VSS are the primary power supply pins for the MCU. This voltage source supplies power to all I/O buffer circuitry and to an internal voltage regulator. The internal voltage regulator provides a regulated lower-voltage source to the CPU and other MCU internal circuitry.

This temperature control will not only be applicable to refrigerators but also to electronic devices that need temperature monitoring. It is a low cost device that may be integrated to appliances, medical and industrial equipment.

Basic Temperature Control for Refrigerators – [Link]

The Art of Representing Floating-Point Numbers as Integers


Mário Ribeiro writes:

Have you been using float or double variables to perform mathematical operations on embedded systems without a Floating-Point Unit (FPU)? You are doing it wrong! That’s incredibly inefficient.

An FPU is an hardware block specially designed to carry on arithmetic operations on floating point numbers. Even though the C/C++ code may work without an FPU, it’s always much faster to use hardware designed for a specific purpose, like this one, instead of relying on a software implementation, something that the compiler will do for you, knowing the hardware restrictions you have but not in an efficient manner. Essentially, it will generate a lot of assembly code, greatly increasing the size of your program and the amount of time required to complete the operation. Thus, if you don’t have an FPU available and you still want to perform those arithmetic operations efficiently you’ll have to convert those numbers to fixed-point representation. Integers! But how? By scaling them. Let’s see how that scaling value may be determined.

The Art of Representing Floating-Point Numbers as Integers – [Link]


DIY soldering station


MatthiasW over at DebuggingLab posted his DIY Weller station clone project, that is available at Github:

At the Forum I read about a DIY Weller station. Basically an Arduino shield to drive a Weller soldering tip. As there is not much to it, the board simply contains an precision OpAmp, a power MOSFET, 2 buttons for adjusting the temperature and a display to show the current values. This design looks like a good starting point for my own advanced project. As I have lately discovered a 1,8 inch SPI TFT at for an amazing price ( ~ 4.60 $ / 3,70 €), I started using them regularly in my projects. So I surely wanted to use it with this soldering station as well.

DIY soldering station – [Link]