RX/TX sequencer

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Lukas Fässler has designed and built an RX/TX sequencer based on a PIC16F18325,  that is available on github:

Much like the beacon keyer presented here earlier, this RX/TX sequencer is a simple but useful little device. Its typical use is in ham radio applications when a separate power amplifier (PA) and/or a sensitive low-noise pre-amplifier (LNA) is used. Care has then to be take to safely transition between RX and TX states – and that’s where this sequencer comes in.

Project info at Soldernerd homepage.

Check out the video after the break.

Bus Pirate PCB build

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Ben Kazemi shares his latest build a Bus Pirate v3.6a PCB.  The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

My latest build – i have to say the yellow soldermask is prettier than it looks on the photos, i also like to think i earnt something special for having ENIG pads :p

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Deepace KC901V 6.8GHz handheld network analyzer review, teardown and experiments

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Teardown and analysis of Deepace KC901V 6.8GHz handheld network analyzer from the The Signal Path:

In this episode Shahriar reviews the Deepace KC901V 6.8GHz handheld network analyzer. This battery-powered instrument is an RF multi-instrument integrating VNA, spectrum analyzer, field strength meter, and a low-frequency signal generator. It can also perform signal port vector measurement and 2-ports simple vector network analyzing (S11, S21).

More details at The Signal Path homepage.

Check out the video after the break.

Pulsecounting and deepsleep based IoT water meter

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Tisham Dhar has written an article detailing his pulsecounting and deepsleep based IoT water meter project:

I admit to being a tiny bit obsessed with monitoring utility bills and gathering data on my usage patterns blow-by-blow. The energy monitoring has reduced my electricity bills, so I wanted to have a go at the water usage. Granted a lot of the water bill is fixed supply costs and sewerage charges which I can’t do much about.
A while ago I made some pulse counting breakouts with the DS1682+ RTC. I have finally got a chance to put them to good use interfacing with my mechanical water meter. The water meter has a spinning permanent magnet and in principle this can trigger a reed switch and generate pulses for accumulation by the RTC.

More details at Tisham Dhar’s blog.

A DC motor controller with control LEDs

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Boris Landoni writes about a new open source project a DC motor controller with control LEDs:

It can be controlled through logic levels to set the speed and the direction of the rotation of CC brushed motors and stepper motors; outputs have LEDs indicating the rotation direction.

The circuit board we are presenting this time is based on the dual-bridge driver L298N, in a traditionally mounted version in a Multiwatt container with 15 staggered pins; it has two terminal blocks for attaching to DC motors or the coils of a bipolar stepper motor and a terminal block for powering logics and motors. Each of the two output channels of the circuit can provide a maximum current of 2 A, which is enough to drive two 2 A direct current motors or a bipolar stepper motor absorbing 2 A per phase.

More info at Open-electronics.org.

App note: Active capacitor discharge circuit considerations for FPGAs

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Power down sequencing and discharging on FPGAs app note from Diodes Incorporated. Link here (PDF)

FPGA’s need the different power rails to be powered up and down in a defined sequence. For power down, each sequenced rail needs to be fully off before the next rail is turned off. With large high speed and high functionality FPGA’s, the power rails have large bulk capacitors to be discharged quickly and safely within a total time of 100ms and up to 10 rails each to be discharged within 10ms.

This application note shows a methodology and considerations for safe open ended shutdown to be controlled by a power sequencing circuit and using correctly chosen MOSFET to discharge the capacitor bank.