USB to RS485 converter


Marko Pavlin has published a USB to RS485 converter. He writes:

Testing of sensors with RS485 using PC without proper interface is not possible. Since RS232 interfaces are very rare, the interface should be hooked to USB. The interface between USB and RS485 can be soldered with one of the many FTDI interfaces with added RS485 driver, or bought as assembled module. There is always the third option. I made it from scratch.

USB to RS485 converter – [Link]

Optically Isolated LPT Breakout Board for CNC & Routers


Optically isolated parallel port  break out board designed for Hobby CNC, Routers and Motion controller, This Board is an easy solution to drive stepper Motor driver through PC parallel port, The Board is compatible with various CNC software specially made for LPT port data output. The board has been tested with MACH3 CNC software.   All outputs are optically isolated and inverse, all inputs are optical isolated and can be used as emergency switch, limit switch, home switch and feedbacks. The Opt coupler and inverter require power supply at both PC side and output side. USB connector and CN5 Screw terminal provided for PC side power supply input and CN4 for output side power supply 7 to 36V DC.

The board has 12 output pins that can control various devices such as stepping motor drivers, Plasma Torch, Pump for coolant, spindle, 5 Input pins are provided for limit or home switches, feedbacks, Emergency switch.  All inputs has 470E for TTL Voltage input required driving the inputs.

Note: For 24V inputs replace R10, R12, R13, R15, and R16 with 2K2 Ohms.


  • Supply 7V to 36V DC output side of opt-coupler
  • 5V DC for PC side
  • 25 D SUB Male Connecter for PC LPT Port Interface
  • High Speed Opto-coupler s 6N137 on all outputs
  • PC817 Opto-coupler for Inputs and Output Controls
  • On Board USB Connector for Supply from PC or other source
  • All Outputs are buffered and optically isolated
  • All inputs are optically isolated
  • Screw Terminals for all outputs and inputs
  • On Board L317 Regulator for 5V DC
  • Heat sink for regulator

Optically Isolated LPT Breakout Board for CNC & Routers – [Link]

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Elektor is more than a magazine, it is a community of active electronic engineers eager to learn, make, design and share surprising electronics. If you would like to join this community by purchasing a yearly membership you may consider this exclusive offer. Elektor, offers 50% discount on yearly membership on all visitors. To benefit from the offer just enter E-LAB16 code on this form. The offer is valid for Elektor GREEN Membership and costs US $37.50 (€34.00 / £24.48) for a year.

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1.8″ DIY Photo Frame using and Arduino Nano and a ST7735 Color TFT display

In this video is  going to show us how to use the SD card slot of the popular 1.8″ Color TFT display which uses the ST7735 driver. Then we will save some bitmap images in the SD card and we will display them on the display. In other words, we will build a simple Photo Frame using Arduino!

If you have watched some of my previous videos, you may have noticed that I use this 1.8” color TFT display a lot recently. The reason for that is that this display is very easy to use, it costs less than $5 and it offers color! At the back, the display has an SD card slot, so I thought that we have to learn how to use that as well. As it turned out, it is really easy to use the SD card slot of the display! That makes this display even better.

The project that we are going to build today is this. A simple photo frame which loads images from the SD card. I have placed some .bmp images in the SD card and the project loads them and displays them at the display in full color! As you can see the speed of the project is very high if we take in consideration that the brains of this project is the old and slow Arduino Nano. In my opinion, this is really impressive. But let’s now see how to build this project.

1.8″ DIY Photo Frame using and Arduino Nano and a ST7735 Color TFT display – [Link]

150V DC/DC inverting controller: single inductor, ground-referenced control


LTC3896 is a high voltage inverting switching regulator controller that drives an all N-channel synchronous power MOSFET stage. Most low to medium power inverting DC/DC converters use a coupled inductor or transformer: this device uses only a single inductor.

The chip converts a 4V to (150V – |VOUT‾|) positive input voltage to a regulated negative output voltage from -60V to -0.8V at output currents up to 15A. Efficiencies are as high as 96%, for transportation, industrial, telecom and power distribution applications.

150V DC/DC inverting controller: single inductor, ground-referenced control – [Link]

Curve Tracer Project


Jason Jones has tipped us with his latest project. He is working on a semiconductor curve tracer and details his progress on his website.

I have thought about this a lot recently and – in order to get the cost down – the unit must have a cheap or available power supply and must coopt the screen for another device.  The first and easiest thing that comes to mind is to simply use USB for the power supply and use your PC screen as the screen.  This is the direction that we will go for the moment in order to keep things simple.  Up to this point, we have a screen and power supply without even starting the design.

Curve Tracer Project – [Link]

How to Use Arduino and a RF 433 Long Range


This is a tutorial on how to use a 433MHz long range transmitter/receiver with Arduino.

I just explain how i have use the 433MHz RF Long Distance Transmitter / Receiver Pair and a arduino to install it on my rc truck for a firework ignition, lamp , pan tilt camera system

How to Use Arduino and a RF 433 Long Range – [Link]

DIY Mini Quadcopter with 3D-Printed Frame and Custom Firmware


Simon D. Levy designed and build a mini quadcopter with 3D printed frame and custom C++ firmware. See the full project notes including bill of materials and more photos on the link below, and check out Simon’s blog on the C++ firmware here.

I wanted to try my hand at a true “DIY” project, designing and building my own micro quadcotper frame and writing my own firmware in C++.  In this post I will describe the frame and build; in my next post I will talk about the firmware.

DIY Mini Quadcopter with 3D-Printed Frame and Custom Firmware – [Link]

Energy monitoring using ATM90E26


Tisham Dhar designed an ATM90E26 energy meter breakout board which can be used in single phase power measurements.

After designing and testing the ADE7763 based Energy Monitor Breakout Board, I started looking around for cheaper and more modern alternatives.I came across the Atmel ATM90E26 Smart Metering IC with dual communication options – UART/SPI and multiple metering modes (tamper proofing with current sensing on live and neutral).

Energy monitoring using ATM90E26 – [Link]

RC snubber calculator spreadsheet


Paulo has developed an Excel-based calculator that eases the design of RC snubbers in power switching applications:

In power switching applications, a designer often has to contend with spurious oscillations. These are the result of parasitic capacitances and inductance on the board and behave like the step response of an RLC circuit. These transients can induced undesired noise in neighboring circuits and create over voltage spikes that can compromise long term component reliability.

RC snubber calculator spreadsheet – [Link]