ESP8266 is really cheap (~$4) WiFi transceiver module that comes in many PCB configurations. WiFi module can be connected to other devices that can access and control it with AT commands, but fun part is that WiFi module can be used as stand alone device which can be programmed with LUA script which could perform simple tasks like connect to WiFi, control GPIOs and toggle LEDs or drive other devices.
Rui Santos have written a nice tutorial where he teaches how to set up a schematic of two LEDs connected to ESP8266 module. Then he demonstrates how to write a simple LUA script using ESPlorer Java based GUI and how to flash device with NodeMCU flasher. His example script enables WiFI module to work as web server where you can access it through web page and turn ON/OFF two LEDs by simply pressing buttons.
When working with power devices it is always good to know what is going on. Especially this is important when experimenting with unknown parameter devices like motors, inductors or batteries. Dorkbotpdx shared a power playground that would allow to run different things and have full control and feedback of process.
He used PMOS/NMOS H-Bridge configuration attached to Teensy-3.1 microcontroller board which runs FreeRTOS. There is a current sensor next to bridge which helps on experiments with PWM motor control, power line synchronization, battery charging/discharging. Four digit 7-segment LED indicator gives a simple visual feedback. This is a great tool for many interesting experiments.
If you are running website on a server you know that many things can happen. It can go down due several reasons and you may notice this only when try to connect or load webpage. In order to avoid long downtimes you need to set up alarm which would ring bells and whistles once it goes down. Kelsey shared a website down alarm project based on Tessel board.
Tessel board simply pings website every second and once trouble is detected it starts alarm which is a large red alarm light. Lamp was modified to be controlled from relay module which plugs directly to Tessel board. Speaking of Tessel boar it is an ARM processor based development board which runs entirely on Node.js. It already has built in WiFi module what makes it great tool for Internet of Things (IoT).
Regular multimeter isn’t convenient to measure parameters of SMD components. Also most of multimeters measure only R and C, but not L and Z(impedance). For SMD components you need tweezers that can reach small contacts. If your budget is limited and you want ZRLC measurement features, then probably go with DIY version. Ajoyraman shared his instructable, where he builds tweezers around TMS320F28027 microcontroller. To switch between modes he uses ADG714 analog switch and rail to rail operation amplifier MCP6022.
To make tweezers small and yet functional, he is not using any displays on them. Instead he connected tweezers to PC via USB where information is seen in nice PC GUI. You can find all codes in GitHub. We have seen how resistance and capacitance and inductance can be measured. More interesting feature in tweezers is impedance measurement. The idea is to generate sine wave and pass it through unknown impedance. By measuring amplitude and phase on target PC software is able to process and display real and imaginary part of unknown impedance. PC software is very well built with complete information for each measurement mode along with graphical representation. It could be great tool on your desk that would cost you no more than $25.