Low cost high accuracy STM32 FFT LCR meter

Adil Malik made a low cost FFT LCR meter with an STM32 MCU:

The approach I took was a mixed signal one where a capable analog front end would be paired up with a beefy DSP processor to compute the Impedance. Most importantly, in this scheme, the DSP is responsible for discriminating the phase between the sampled voltage and current waveforms; this approach is preferred because it leads to good accuracy and calibration stability.

See the full post on his blog.

DIY inline refractometer

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DIY inline refractometer project from Anfractuosity:

The idea of this project is to image the refractometer output, then convert the position of the blue line, to a digital reading, using image processing. The idea is to measure the brix of wort during mash and sparging, so that sparging can be stopped around 1.010 SG, to avoid tannins.

More details on Anfractuosity blog.

Check out the video after the break.

PLA dielectric strength measurement

PLA Dielectric Strength Measurement

Kerry Wong did some experiment measuring the dielectric breakdown voltage of PLA:

In my previous post, I designed and 3D printed a high voltage connector for my Bertan 225-20R high voltage power supply. The silicone high voltage wire I ordered had finally arrived so I made a couple of cables using the connectors I printed. A few of my viewers had questioned the suitability of using PLA as printing material in high voltage applications so I decided to measure the dielectric breakdown voltage of PLA and gather some real-world data.

See the full post on his blog here.

Check out the video after the break.

CurrentRanger: auto-ranging current meter

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An auto-ranging nanoAmp meter from LowPowerLab:

CurrentRanger is a nanoAmp current meter featuring auto-ranging, uni/bi-directional modes, bluetooth data logging options and more.
It is a highly hackable and affordable ultra low-burden-voltage ammeter, appropriate for hobby and professional use where capturing fast current transients and measurement precision are important.

More details on LowPowerLab site.

Check out the video after the break.

 

 

TRL measurements with homemade VNA and open source software

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Henrik Forstén writes:

I have been using the OSH Park’s 4 layer process a lot on my own projects. It has FR408 substrate that has better controlled permittivity and lower losses than ordinary FR-4 that other low cost PCB manufacturers use. In my opinion currently it is the best low cost process for making RF PCBs. My previous boards have worked pretty well, but I decided to make a test board that I can use to characterize the process better.
In the above picture is the test board that I made. It has two 50 ohm microstrip lines of different length, one open microstrip line, one microstrip line terminated with 50 ohm resistor and line with 0402 footprint that I populated with a 1 nF capacitor. I’m using this same type of capacitor as a general DC blocking capacitor in my VNA so I’m interested in finding out how it performs at high frequencies.

See the full post on Henrik’s blog.

Stand-alone simulated analog meter

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DuWayne S blogged about his stand alone simulated analog meter project:

Thinking about what values I would like to display, I came up with three basic items.  A S-meter when in receive, and a power output display when in transmit.  In transmit, I would also like to have the capability of measuring VSWR.  Thinking about the switching functions required for this I will need one control line that monitors  transmit/receive, this can come from the PTT or key line in the transceiver.  Then  I use a second control line to select either power or VSWR when the T/R line is in transmit.  Another control line can do the same for the S-meter or some other display when in receive.  Since this is based on a VU meter, I will use that for the secondary function in receive.  Now looking at the signal lines I need to measure, they are the AGC line for S-meter, audio signal for VU meter.  And in transmit, the forward and reverse power levels will take care of power and a computed VSWR reading.

See the full post at DuWayne’s Place blog.

Debug SONOFF AC relay with a thermal camera

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James Lewis shares his experience in debugging SONOFF AC relay with a thermal camera:

The clever solution seemed to be clever, at least for a few minutes. Suddenly the light turned off. I thought maybe there was a timeout for the manual button. Annoying, but workable. The lamp remained off for about another 2 minutes when I started to smell that unmistakeable burning plastic odor. Touching the case of the SONOFF identified the culprit immediately.
Great. So I have an AC mains switch that isn’t working, but I do not want to go poking my multimeter into it. What do I do?
Turns out, that SONOFF module was defective. I wanted to debug it, but I did not want to measure anything while connected to AC. Here’s how I used a thermal camera to debug my SONOFF.

See the full post on Bald Engineer blog.

ATM90E36 Dev-kit for 3-phase AC metering

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Tisham Dhar blogged about his ATM90E36 3-phase energy monitor project:

After successfully building the single-phase energy monitor with the ATM90E26 there has been lots of interest in the 3-phase version. Being an open-hardware project, many people have created remixed and derived versions as well. After a while I started receiving requests to assist with the code for ATM90E36, the 3-phase version of the Energy Monitor chip. However I did not have the hardware to test the code, so I put together this basic devkit to access the SPI bus and easily inject voltage and CT signals to take the ATM90E36 through its paces. This is the first board I have designed based purely on user demand rather than to scratch my own itch, since I don’t have 3-phase supply at home.

Project info at Tisham Dhar’s blog.

Check out the video after the break.