Basics of Phase Dots on Transformer Windings

This video describes what the “phase dots” are that you often see adjacent to windings of a transformer. It discusses how these dots are used in certain circuits to establish a desired phase relationship between the signals on the various windings. A couple of tips are given regarding how to determine the phasing relationship on homebrew transformers. Finally, measurements are made with an oscilloscope on a trifilar wound transformer to see the phase relationship between the signals on each of the windings with respect to the phasing dots.

Basics of Phase Dots on Transformer Windings – [Link]

Analog Ultrasound Range Finder


by netzener @

When I started my career in control systems I was fascinated with the many different ways that machines could be interfaced to the environment they operated in. Limit switches (electrical and optical), encoders, resolvers, strain gauges, thermocouples… the control system engineer had a long list of sensors to choose from. And the list has grown even longer following successful innovations in micro machining.

Analog Ultrasound Range Finder – [Link]

UT204 is able to measure DC current and also True RMS


Clamp multimeter UT204 measures reliably even in real conditions of nowadays mains supplies and for an affordable price moreover.

UT204 from company UNI-Trend is a near relative to the UT203. multimeter. Already UT203 provides a lot of user comfort and a very pleasant feature – measuring of a DC current without interrupting a measured circuit. However UT204 is different from its “weaker” brother in one essential thing – it enable measuring of a true RMS value of alternating signals (TRMS).

As we know, usual multimeters usually deploy a simple rectifier and an RC cell and they´re calibrated to show an effective value of AC voltage – supposing an ideally sinusoidal shape of a measured variable.

In many cases, a non-TRMS multimeter is fully sufficient, but still more frequently we meet devices, which by their power consumption significantly deform originally sinusoidal shape of a mains line voltage. A vast majority of new devices is equipped with switch-mode power supplies deforming a sinusoid, as they draw current for charging of input capacitors mainly on a top of a sinusoid. This situation is partially better at power supplies with a power factor correction (PFC), but even in these cases it´s never an ideal load. At any difference from an ideal sinusoid the accuracy of a common meter significantly drops down and the error can exceed tens of percents. Similar situation is also at various DC/AC inverters (for example 12VDC/230VAC), whose output is usually only an approximated sinus.  

That´s why if exact measurement matters to us, it´s more certain to measure by a device equipped by a TRMS measurement. There are many types with this function on the market, and in a segment of clamp multimeters it´s for example the above mentioned UT204, which moreover offers a lot of other functionality for an excellent price.

Detailed information and comparison of UT203/ UT204 will provide you the UT204 datasheet and the UT204 datasheet and UT203-204 user guide. We keep Uni Trend UT204 as a standard – immediately available item.

UT204 is able to measure DC current and also True RMS – [Link]

RFM69HCW transceiver can go up to 20dBm


This powerful RF transceiver is also highly secure thanks to a HW support of CRC-16 and AES-128.

The RFM69HCW is a highly integrated RF transceiver capable of operation over a wide frequency range, including the 433, 868 and 915 MHz license-free ISM (Industry Scientific and Medical) frequency bands. Its highly integrated architecture allows for a minimum of external components whilst maintaining maximum design flexibility.All major RF communication parameters are programmable and most of them can be dynamically set. The RFM69HW offers the unique advantage of programmable narrow-band and wide-band communication modes without the need to modify external components. The RFM69HW is optimized for low power consumption while offering high RF output power and channelized operation. TrueRF™ technology enables a low- cost external component count (elimination of the SAW filter) whilst still satisfying ETSI and FCC regulations.

On stock we also keep a less powerful version – RFM69CW, suitable for all applications where a lower range is sufficient.

RFM69HCW transceiver can go up to 20dBm – [Link]

Arduino dust sensor


Shadowandy’s Arduino-based Dust Sensor project:

Put together a dust sensor using Arduino Mega 2560, Shinyei PPD42NS dust sensor and LCD shield.

The codes and wiring instructions for Arduino Mega 2560 and Shinyei PPD42NS is as follow. However, I did include Serial output so you can view the sampling results using Arduino IDE’s Serial Monitor (9600 bauds).

Arduino dust sensor – [Link]


RS232 To RS485 Module


RS232 to RS485 Board (R) provides a seamless connection of the PC to an RS485 network.

  • Simplex connection of this interface to the RS485 network
  • Easy way of switching the modes between Receiver and Transmitter ( Slide Switch)
  • 5 V regulated supply provision on board
  • 9-pin, PCB mounted, Female type D-connector available
  • Supply can also be provided by the host interface via Header connector carrying data
  • Four mounting holes 3.2 mm each
  • PCB dimensions 82 mm x 33 mm

RS232 To RS485 Module – [Link]

DTMF Module


DTMF Development Board offers a very convenient way to generate DTMF tones and demodulate it.  It uses the famous MT8880/MT8888 DTMF transreceiver IC.

  • Easy 10 pin Box Header connector for interfacing data/control pins
  • Crystal derived frequency source for accurate generation and demodulation of DTMF tones for your project
  • Onboard upto 350 mW audio amplifier block for DTMF tones with Volume Adjust Preset
  • 5V Supply sourced via interfacing Box Header
  • Header  type analog connection
  • Four mounting holes 3.2 mm each
  • PCB dimensions 56 mm x 49 mm

DTMF Module – [Link]


Matchbox car


Shane has been working on making small robots and made a prototype of a matchbox car, a robot car that fits inside a matchbox:

This build consists of a tiny DC motors ripped from a pair of 9g servos, a h-bridge motor controller, an el-cheapo 8 bit pic and a 100mAh 3.7V LiPo battery.

Matchbox car – [Link]

Arduino-based “Analog” slow cooker controller


Dan Ternes blogged about his Arduino-based controller for analog slow cookers:

With the AC power control figured out, I considered the User Interface. I opted for something simple. The Adafruit RGB LCD Shield would work well as it had both a display and buttons built in. Sure, I could have beat this project about the head and neck with “IoT”-this and “ESP8266″-that, but I was feeling lazy and just wanted a simple timer control. Of course, there’s nothing that says I won’t add some kind of wireless connectivity, but for now, local control is fine.

Arduino-based “Analog” slow cooker controller – [Link]

Tic-Tac TV Remote Jammer


by DangerousTim @

That moment you take your eyes off the TV remote for just a second, because of which it falls into the hands of your annoying sibling. Yes, fighting for control over the TV is a daily struggle for many. But the TV Remote Jammer shown in this Instructable, will make everyone else stop dead in their tracks.

This Remote Jammer circuit, in the disguise of an inconspicuous TicTac Box, sends a constant signal to the TV receiver that interferes with the signal from the TV remote. This means that when the Jammer is on, your TV remote CANNOT be used to change channels. It practically blocks all signals from the remote.

Tic-Tac TV Remote Jammer – [Link]