Electronics – JackenHack

Calibrating Brymen BM-Series Multimeters

September 27, 2017 by Jack Zimmermann 2 Comments

Easy Way To Calibrate a Bryman BM869s Multimeter

After replacing my lost Fluke 87V multimeter with a new Brymen BM869s (rebranded Greenlee in the US) about a year ago, I’ve been delighted with the multimeter. It has every possible function I could ask for and then some. It’s been my go-to meter when working on electronics projects. I do have a Siglent SDM3055 DMM that is very good, but due to its startup time, I usually reach for my Brymen BM869s when I need to measure something, and it has higher resolution. But after getting a broken HP/Agilent 34401A DMM from eBay, fixing it up and replacing all the capacitors, I now have a better reference. I’ve compared it to my friend’s calibrated 6 ½-digit multimeter, and it’s still within spec, so naturally, I want my Brymen to be as close to my HP 34401A as possible. Turns out that calibrating and adjusting the Brymen is quite easy. Here’s how to do it.

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NTP Server Extreme accuracy for under $200 Using SI5351C

April 13, 2017 by Jack Zimmermann 2 Comments

When you make your own NTP server, you probably spend a lot of time trying to get it as accurate and stable as possible. To get good results, you need to connect your server to a good time reference, like an atomic clock, GPS or a GPSDO to get the PPS (Pulse Per Second) to sync your server with the reference clock.

In both Linux and BSD, there is kernel support to slave the very inaccurate CPU clock crystal to the PPS signal, continually adjusting the frequency, because the crystals of computers continuously drift due to temperature and barometric pressure differences. So most of the work is to get a crappy crystal to behave. What if you just jumped over that step, so the CPU clock gets synchronized with the same lab reference that the PPS signal uses, using a SI5351C Clock Generator?

Read on to see a simple way of doing it and get an extremely accurate NTP server for under $200.

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Atten 8502D Pinout Replacement Iron Heating element

March 23, 2017 by Jack Zimmermann Leave a Comment

So you need to replace the soldering iron on your Atten 8502D Soldering Station. You could just buy the heating element, but you can find a complete soldering iron with cable for less than $12 on eBay. So It’s easier just to replace the whole thing.

It Doesn’t Work!

I have ordered replacement irons before (I’m very rough with my soldering station) just to find out that they don’t work. You get the dreaded S-E or H-E message on display and, obviously, something is wrong. What do you do now? Read on to find out.

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Sonoff WiFi Smart Switch With I2C Port

March 21, 2017 by Jack Zimmermann 11 Comments

How to add an I2C interface to a Sonoff WiFi Smart Switch.

The Sonoff brand is a whole series os IOT devices that use the esp8266 WiFi processor internally. The devices are easily hacked and are cheap. The Sonoff WiFi Smart Switch is the most straightforward device, which can turn on or off 110/220 Volt 10 Ampere remotely. That means you can have your ceiling fan, lamp or anything else connected t mains power remotely controlled by your phone or computer. But the software that comes with it isn’t very flexible and cannot be integrated into a home control system like NodeRED, OpenHAB or any other home automation system.

Firmware

The Sonoff devices are easy to hack, so you can put a better firmware like ESPEasy on it and integrate the device with any system. ESPEasy has an extensive list of extra modules that you can connect, like temperature, barometric pressure, humidity, light sensors, PIR sensors and a long list of other things.

But most modules connect with I2C, which is a serial interface for interconnecting ICs using a clock and a data line. The Sonoff Switch only have one extra pin available, making it impossible to connect more advanced sensors. But there is a way of fixing that. Here’s how to add that to add an I2C connector to your $5 Sonoff and open up a whole field of stuff you can do.

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Cable Impedance How to Measure It

March 16, 2017 by Jack Zimmermann 8 Comments

What kind of impedance does this coax cable have?

Sometimes you dig around in your parts bin, desperately searching for a bit of coax cable to make a new connector to your fantastic whizzbang widget. If you find a piece of cable without markings, how do you know if it’s 75Ω, 50Ω or some other impedance? Well, here are two easy ways of finding out.

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