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29 Nov 2014

by  TheSignalPathBlog @ youtube.com:

In this episode Shahriar repairs an Agilent 33250A function and arbitrary waveform generator which does not power on. The unit is equipped with a soft power switch which might be responsible for the fault. After a brief look at the unit’s constructions, the fault is traced to a few possible locations.

The schematic of the soft power circuitry is presented and the internal switching power supply is closely examined. After the fault is located, the repair is presented. The block diagram and operation of a current mode DC-DC switching IC is also presented.

Teardown and Repair of an Agilent 33250A Function and Arbitrary Waveform Generator - [Link]

29 Nov 2014

What’s inside a smart card pinpad EFTPOS terminal?
Dave looks at the anti-tamper mechanisms inside a Sagem Monetel EFT930S

EEVblog #687 – EFTPOS PIN Pad Terminal Teardown - [Link]

29 Nov 2014


Limpkin has build a development board for the ESP8266-03:

The ESP8266 modules come with a pre-loaded firmware that will accept some commands through their UART interface (connect to wifi, open udp socket, send data to this IP…). Moreover, since Espressif recently released their SDK you can now load your own custom programs using the existing bootloader. To launch this bootloader you just have to connect some IOs to GND in a specific order.
However, anyone wanting to develop a project involving dozens of Wifi nodes has to start from somewhere, eg make a prototype of their future platform. That is why I developed this development board, so the prototyping stage is as simple as possible.
As you can see in the picture below the dev board breaks out all the ESP8266-03 IOs, includes a 3.3V LDO, a USB to UART converter, some logic and a button to automatically start the bootloader.

A development board for the ESP8266-03 - [Link]

28 Nov 2014


Here is another piece of laboratory equipment – LC meter. This type of meter, especially L meter is hard to find in cheap commercial multimeters.

Schematic of this one came from this web page: https://sites.google.com/site/vk3bhr/home/index2-html

It uses PIC microcontroller 16F628A, and because I recently acquired a PIC programmer, I decided to test it with this project. Following the above link you will find the original schematic, PCB, source and HEX files for programing the microcontroller and detailed description.

Simple PIC LC meter - [Link]

28 Nov 2014


Raj @ embedded-lab.com shared his recent project. It’s a mcu controlled dice based on PIC mcu:

Tons of LED dice projects with different output forms have been published online. The most common output configuration in those projects is a 3-1-3 setup (two rows of three LEDs and one LED at in the middle) of seven LEDs, which simulates the actual patterns of dots found on the six faces of a traditional dice. When it is rolled, one or more LEDs are selectively turned on to display a random number between 1 to 6. This project is about a similar LED dice but with a slightly different output form. It uses 6 LEDs which are arranged in a circular pattern and are labeled 1 through 6. They create a chasing effect when the dice is rolled. The chasing effect slows down gradually, and eventually stops at one of the six LEDs. The rolling is done by a gentle shaking of the dice horizontally. The LED dice is powered with a 3V coin cell battery and uses PIC12LF1822 microcontroller to generate a random number and drive the output LEDs.

MCU running LED dice - [Link]

28 Nov 2014


A battery charger is a device used to energize a rechargeable battery by driving an electric current through it. The charging protocol depends on the size and type of the battery being charged. Some battery types have high tolerance for overcharging and can be recharged by connection to a constant voltage source or a constant current source; simple chargers of this type require manual disconnection at the end of the charge cycle, or may have a timer to cut off charging current at a fixed time.

The MCP1631HV multi-chemistry reference design board is used to charge one, two, three or four NiMH batteries or one or two cell Li-Ion batteries. The board uses the MCP1631HV high speed analog PWM and PIC16F883 to generate the charge algorithm for NiMH, NiCd or Li-Ion batteries. It is used to evaluate Microchip’s MCP1631HV in a SEPIC power converter application. As provided, it is user programmable using on board pushes buttons. The board can charge NiMH, NiCd or Li-Ion batteries. It provides a constant current charge (Ni based chemistry) and constant current / constant voltage (Li-Ion) with preconditioning, cell temperature monitoring (Ni based) and battery pack fault monitoring. Also, the charger provides a status or fault indication. It automatically detects the insertion or removal of a battery pack.

The MCP1631 multi-chemistry battery charger reference design is a complete stand-alone constant current battery charger for NiMH, NiCd or Li-Ion battery packs. When charging NiMH or NiCd batteries the reference design is capable of charging one, two, three or four batteries connected in series. If Li-Ion chemistry is selected, the board is capable of charging one or two series batteries. This board utilizes Microchip’s MCP1631HV (high-speed PIC® MCU PWM TSSOP-20). The input voltage range for the demo board is 5.3V to 16V.

Multi-Chemistry Battery Charger from Microchip - [Link]

28 Nov 2014


by elektor.com:

In a bid to encourage greater use of TI’s Programmable Real-time Unit (PRU) built into the Sitara AM335x and AM437x family of devices which power the BeagleBone Black development board Texas have announced the PRU cape. The PRU is made up of dual 200 MHz coprocessors, implementing a low-latency subsystem optimized for deterministic, real-time processing allowing direct access to I/Os. It would be fair to say that this capability is seldom used by BeagleBone developers because it has been found to be complex to program.

The Texas PRU Cape - [Link]

28 Nov 2014


Headless Ghost is a display emulator (dummy plug) that fits discreetly in to a HDMI socket.

It fixes a problem you probably didn’t even know you had – unlocking the full potential of your graphics card hardware.

By simulating the presence of an attached display, Headless Ghost allows you to use all of the power and available resolutions locked away inside your graphics hardware, which might otherwise be disabled when there is no screen available.

Headless Ghost – HDMI emulator - [Link]

28 Nov 2014


by elektor.com:

Linear Technology Corporation has announced the LTC2983 high performance digital temperature measurement IC. The IC is a single chip solution to temperature sensor interfacing; it has 20 input channels for sensor connection and each input can be assigned the characteristics appropriate to the sensor used. This includes 8 standard thermocouple types, 8 RTDs, 8 thermister profiles and an external diode; if you are using a custom sensor you can also specify a custom table.

In addition to the impressive sensor capability the IC measures temperature with an accuracy of 0.1°C and a resolution of 0.001°C. The LTC2983 allows direct interfacing to ground referenced sensors without the need for level shifters, negative supply voltages, or external amplifiers. All signals are buffered and simultaneously digitized with three high-accuracy, 24-bit ΔΣ ADC’s, driven by an internal 10 ppm/°C (maximum) reference.

High Accuracy Universal Temperature Sensor IC - [Link]

27 Nov 2014


This project is an audio amplifier based on TDA2050 and LM1875.

This is not an ordinary project, but an attempt to make a PCB that is suitable for TDA2050 and LM1875 and has all the necessary circuitry on board – power supply, speaker protection, delayed turn-on and fast turn-off. This is achieved using the convenient uPC1237 IC.

TDA2050 and LM1875 are pin to pin compatible, the differences in their schematics are the values of a couple resistors and one capacitor. All this allows to make an universal circuit board, suitable for any of these two ICs.

Audio Power Amplifier with TDA2050 - [Link]





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