If you are on the lookout for a $25 Multimeter (or $15 on eBay) for working with low voltages, the best one right now in my opinion is the cute and tiny Aneng AN8008 TrueRMS Multimeter. It has a lot of functions and can measure µA current and It’s a 9999-count meter. The continuity tester is reasonably fast, but there is one little problem that bothered me. It takes 5 to 10 seconds for it to settle on a correct voltage reading. When it finally settles, it’s spot on, but the waiting is annoying. But fortunately there is a simple fix for this problem.
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’s been 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 a friends 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.
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 an 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, constantly adjusting the frequency, because of the cheap crystals of computers constant 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 is as accurate as the PPS signal and used a SI5351C Clock Generator?
Read on to see a simple way of doing it and get a extremely accurate NTP server for under $200.
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, or for a little more on Amazon. so I’ts 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 the display and obviously something is wrong. What do you do now? Read on to find out.
The Sonoff brand is a whole series os IOT devices that uses the esp8266 WiFi processor internally. The devices are cheap and are easily hacked. The simplest device is the Sonoff WiFi Smart Switch, which is a small device that can turn on or off 110/220 Volt 10 Ampere remotely. That means the you can have your ceiling fan, lamp or anything else connected t mains power remotely controlled by your phone. But the software that comes with it isn’t very flexible and can not be integrated to a home control system like NodeRED, OpenHAB or any other home automation system.
Fortunately the Sonoff devices are easily hacked, where 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.