$14.5 All-Purpose Switched-Mode Power Supply

Switching technology devices and integrated circuits are growing fast providing solutions that obtain power for different kind of circuits and devices, and they are proposed in different variations. A useful little known kind which is suitable for mixed supply systems is called SEPIC,single-ended primary-inductor converter.

Torpedo is a switched-mode power supply with a SEPIC configuration which is produced by Open Electronics, an open source solutions producer and the brainchild of Futura Group Srl. It supports three different wide-range voltage sources, battery, USB, and external source from 3 to 20 volts with up to 1 A output current and integrated LiPo battery cell charger.

Torpedo Board
Torpedo Board

Torpedo comes with these features:

  • Triple power source, that is to say: the USB, the battery and an external one
  • Wide range of values as for the input voltage: from 3 to 20 volts
  • Minimum output current of 500mA, with the possibility to reach 1A and more, via an external source
  • High efficiency, above 70% and possibly above 80-90%
  • Single-cell LiPo battery charger incorporated
  • A transition from battery power to another source that is without interruptions
  • 5 V output with high stability, having a low ripple and when varying the load.

Torpedo’s circuit structure can be functionally divided into three different parts; Input Stage, Battery Charger, and SEPIC Converter.

At first, the Input Stage is composed of two diodes and a MOSFET transistor. This set forms a power source selector by allowing the highest voltage power source to pass through Vin pin and prevent it from going to another input having a lower voltage.

Torpedo Circuit Diagram
Torpedo Circuit Diagram

The Battery Charger is based on the MCP73831-2 integrated circuit, that is envisaged for charging single-cell LiPo batteries having a voltage of 4.2 volts. It comes with a red LED indicating the statues of charging, and a two-resistor bridge giving two different output current, 100mA and 500mA.

The SEPIC Converter in general is a DC/DC converter which control its output to be greater than, less than, or equal to that at its input. In Torpedo circuit, the SEPIC integrated circuit contains 1.2Mhz oscillator with variable duty cycle, a low-RDSON MOSFET, and a feedback circuit. This combination provides constant 5V output voltage from variant input voltage between 2.5V to 20V.

Torpedo is available for $14.5 from Open Electronics store, and its technical details are reachable here.

Making a Geiger counter with 555 timer IC

Radioactive particles are found abundantly in nature. Whether they come from space or generated on Earth (radioactive waste, medical X-rays, etc), they are high-energy particles resulting from radioactive decays. The three major types of radioactive particles are named after the first three letters of the Greek alphabet: α (alpha are helium nuclei), β (beta are high-speed electrons), and γ (gamma are high-energy photons). Exposing to any of these radiation for a long time can be dangerous as they can kill DNA and cause cancer. The presence of beta particles and gamma rays in your surrounding can be detected using a Geiger-Muller (GM) tube in conjunction with some basic electronics.

The GM tube is essentially a tube filled with an inert gas (at low pressure) and two electrodes at its opposite ends. A high voltage (~400-700V) is applied between the two electrodes but no current flows between them under normal condition. When radioactive particles passes through the tube, some of the gas molecules get ionized, which results in a short intense pulse of current between the electrodes.

Geiger-Muller tube operation (Source: Wikipedia)
Geiger-Muller tube operation (Source: Wikipedia)

The following circuit (originally published on Elektor July 2006 magazine) illustrates how a GM tube can be used with some basic electronics to make a radiation detector, often known as Geiger counter. The circuit uses two 555 timer ICs. The first 555 timer is setup as an astable multivibrator and drives a step up (6V-to-250V) transformer through a transistor to generate 250V alternating voltage. The high voltage output from the transformer is further amplified using a voltage multiplier circuit made of diodes and capacitors to derive a ~700V source required for the GM tube. When a radiation is detected, the current flow through the tube triggers the second 555 timer circuit, which is configured to produce a tick sound on a speaker when triggered. The output from the second 555 timer can be further fed to a counter circuit for counting the detected pulses.

Geiger counter using 555 timer ICs
Geiger counter using 555 timer ICs

More recently, tanner_tech published an Instructable on building a similar Geiger counter using a single 555 timer and a piezo buzzer. His GM tube operates at a much lower voltage (~400V).

Geiger counter made by [tanner_tech]
Geiger counter made by [tanner_tech]

Tiny OLED PC Performance Monitor


Rupert Hirst build a tiny OLED PC performance monitor based on Psyrax’s serial monitor. The display monitors CPU and GPU temperature and activity etc. He writes:

After a recent purchase of a Nvidia GTX1080 graphics card, 4k monitor plus Doom(2016), I thought it would be great to see some external telemetry… from my exorbitant purchase.
Then, I Stumbled upon on Psyrax’s “Serialmonitor” GitHub repository! Armed with an Arduino ProMicro plus a 128×64 pixel OLED display, I compiled the source code. After compiling Psyrax’s windows application in Visual Studio, I got to work.

Tiny OLED PC Performance Monitor – [Link]

MCU based LED VU Meter


dannyelectronics.wordpress.com discuss about how to build a mcu based LED vu meter and provides sample code.

From time to time, I see people trying to build an audio VU meter. In the analog era, that’s typically done with a voltage divider + a series of comparators; or using chips like LM3914/3915.

Those chips are harder and harder to find, or you may need more resolution, or a different output profile. What to do?

Modern MCUs offer an easy solution

MCU based LED VU Meter – [Link]

RC Signal Monitor Using Bargraph & RC Switch using Relay

The versatile Bar-Graph SMD components based R/C monitor & R/C switch is a great tool for R/C hobbyist R/C modeller and DIY robotics. Tiny Bar-Graph displays provide a Red color bright, easy to read display of Radio Control (R/C) signal from 1mS to 2mS. The Barograph RC Signal reader is based on PIC16F886 microcontroller. This high performance measurement device, provides unique capabilities and can be used in various applications like Radio Signal Monitor, Robotics, Machine Control, RC Remote Tester, RC Signal ON/OFF switch by connecting Relay board or Solid state relay at output of any suitable LED. Solder Jumpers provided on bottom side of PCB to select particular output to interface with Relay or Solid state Relay.

RC Signal Monitor Using Bargraph & RC Switch using Relay – [Link]

ESP8266 16MB Flash Handling


Piers Finlayson shares his adventures in programming the ESP8266 to access 16MB flash:

To put this in context, the original ESP8266 modules (such as the ESP-01) offered 512KB of flash, with the more recent ones (ESP-07) 1MB and then 4MB. The maximum addressable flash memory of the ESP8266 is 16MB according to the datasheet. (The ESP32 offers up to 4 x 16MB of flash.)

I don’t have a particular need for > 4MB flash (otb-iot currently only requires and supports 4MB) but my interest was tweaked in the larger flash chips, so I thought I’d give it a go. I’ve experience of replacing flash chips from older modules to upgrade them from 1MB to 4MB, so figured 16MB would be the same.

ESP8266 16MB Flash Handling – [Link]

MPPT solar charger


Lukas Fässler show us his progress on the MPPT solar charger:

One of my main goals with this design is to achieve very low standby current, somewhere in the tens of microamps. The basis for this is a low-power buck on the basis of a Texas TPS62120 where the microcontroller can switch the output voltage between 2.2 and 3.3 volts nominally. This works as intended. With no load and the output voltage low, the supply consumes 12.9 microamps at 12V input voltage. With the high output voltage the idle current goes up to 14.3uA. Quite a bit of that current is due to the voltage divider that sets the output voltage. The regulator itself consumes about 9uA in both cases.

MPPT solar charger – [Link]

RFID Tutorial with an Arduino Uno and an OLED display

educ8s.tv uploaded a new video on a RFID Arduino Tutorial:

Today we are going to build a very interesting project. For the first time we are going to use RFID tags with Arduino. I have built a simple project which reads the Unique ID (UID) of each RFID tag we place close to the reader and displays it on this OLED display. If the UID of the tag is equal to a predefined value that is stored in Arduino’s memory, then in the display we are going to see the “Unlocked” message. If the Unique ID of the card is not equal to the predefined value, the Unlock message won’t appear. Cool isn’t it?

RFID Tutorial with an Arduino Uno and an OLED display [Link]

C.H.I.P Pro The New GR8-Based Module

NextThing Co., is a hardware company that has the goal to create things that would inspire creativity, and help people chase their own ideas of what needed to exist.  After producing their world’s first $9 computer C.H.I.P, they are ready now to launch a new product!

chippro_project_imgC.H.I.P Pro,  the newest addition to the Next Thing Co. family, is powered by GR8, a system-in-package (SiP) that was designed by Next Thing Co. GR8 features a 1GHz Allwinner R8 ARM Cortex-A8 processor, Mali400 GPU, and 256MB of Nanya DDR3 DRAM. in a 14mm x 14mm FBGA package. C.H.I.P. Pro is a system-on-module (SoM) that has 512MB of high-speed NAND storage flashed with NextThing Co.’s GadgetOS. Gadget is an Open Source Linux-based OS, software toolchain, and cloud infrastructure which is designed to bring the speed, openness, and productivity of modern software development to the world of embedded hardware. C.H.I.P Pro can be powered by USB or battery, intelligently managed by the AXP209 power management unit.

The Pro also features 802.11 b/g/n WiFi, Bluetooth 4.2, and is fully certified by the FCC. This board will be available in December at supposedly any quantity for $16.

C.H.I.P Pro block diagram
C.H.I.P Pro block diagram

C.H.I.P Pro design defines two possibilities of installations; either in a product or in a single board computer designed for a breadboard. Its SMT-ready castellated edges and elements on both sides will make reflow soldering not so preferable. Instead, header pins, a ‘debug board’, and two C.H.I.P Pro units are introduced in one package for only 49$ to make soldering easier and to start installing the unit in applications. Due to its size and efficiency, it could be a good competitor for Raspberry Pi Zero.

C.H.I.P. was designed to be used in computer powered products, but it was recognized later that it wasn’t always the best fit. Many of the design choices of C.H.I.P make it hard to build into products. C.H.I.P. Pro addresses this issue, implements feature requests from the community, and is engineered to embed in products. C.H.I.P. and C.H.I.P. Pro are similar in many important ways, but they differ in some features. Here are C.H.I.P Pro advantages:

  • Industrial Grade —512MB SLC NAND
  • Updated Realtek WiFi / BT chipset with B/G/N & BT 4.2
  • Digital Audio / Support for SD Cards via pins
  • USB Breakout for PCB Designs incorporating USB based peripherals
  • Breadboard and SMT Placeable
  • A complete suite of certifications: WiFi Alliance, Bluetooth Consortium, FCC, CE, ROHS
  • Based on GR8 making it 76% smaller than C.H.I.P.
  • Better power consumption with ~3mA suspend to RAM

chipcoC.H.I.P. Pro is powered by GR8, a system-in-package provides a powerful application processor and DDR3 SRAM which eliminates the need for high-speed routing and reduces manufacturing complexity. GR8 is $6 in any quantity and includes the Allwinner AXP209 power management unit.
GR8 also features many popular peripheral interfaces: Two-Wire Interface, two UARTs (one 2-wire and one 4-wire), SD Card-ready SPI, two PWM outputs, a 6-bit ADC, I2S digital audio, S/PDIF IEC-60958 digital audio output, two HS/FS/LS USB PHYs (one USB 2.0 Host and one USB 2.0 OTG), a CMOS Sensor Interface.

GR8 Block Diagram
GR8 Block Diagram

Although it is doubtless that C.H.I.P. Pro will be installed and used in various projects, making GR8 module available for customers is something huge. Providing a jellybean part that contains an entire Linux system makes it possible to add the power of open software into any project and it opens the door for more applications to come.

Further details can be reached at C.H.I.P Pro and GR8 datasheets and at NextThing Co. forums.

Via: Hackaday

That’s how nano solar cells work!

by Harry Baggen @ elektormagazine.com

Researchers from the AMOLF institute and Eindhoven University of Technology have developed a theory and an experimental method that for the first time provide a detailed description of how a nanoscale solar cell works. Previously this was difficult due to the extremely small dimensions of these solar cells. This new method brings the practical use of nanotechnology for sustainable energy supply a step closer.

That’s how nano solar cells work! – [Link]