Engineering in July: an ESP32 battery monitor, a DIY servo motor tester, and more

Whether you’re looking for a cloud-based battery monitoring solution or want to build a servo motor test circuit, Elektor has an article for you. And summer is the perfect time to dive into a new engineering project, right? Check out the following projects from previous Elektor editions in July.

Whether you’re looking for a cloud-based battery monitoring solution or want to build a servo motor test circuit, Elektor has an article for you. And summer is the perfect time to dive into a new engineering project, right? Check out the following projects from previous Elektor editions in July.

ESP32 Battery Monitor (July 2019)

You can easily measure analog values ​​with an ESP32 board, then send the data, via Wi-Fi, to a router and the ThingSpeak platform. This July 2019 article walks you through the process, especially because wiring a PCB isn’t necessary.

The design can measure three channels via Wi-Fi and Thingspeak. Set foot in the cloud!

Platino soldering station (July 2015)

Interested in SMD soldering stations? In the summer of 2015, Elektor introduced an affordable and quite practical soldering station built around the Elektor Platino Controller board. The unit was ideal for soldering SMD components and more.

Plantino Soldering Station - Engineering in July

Its main characteristics were: power supply (12 to 18 V DC, 5 A); Elektor Platino with ATmega328P microcontroller; 16×2 LCD; Weller type RT soldering tip with 3.5 mm jack connector; a three-pole jack socket to accept the 3.5 mm stereo jack plug; temperature selection range from 90°C to 450°C; temperature control via Platino PWM signal; display showing actual and set bit temperature; and a rotary encoder to select the setup temperature.

Hunter (July 2007)

If you love DIY robots, you’ll love the four-legged robot Hunter. The compact robot can detect moving hot objects, such as people and animals, from a greater distance using a PIR sensor. The design includes an Atmel AT90S2313 microcontroller, which has 2 KB of program memory, which provides enough space to program intelligent behavior.

hunter project

As long as the robot can see something, it will chase it. If he sees nothing, he takes five steps in the hope of seeing something. After these five stages, it remains upright and waits for new prey.

Quad Car Amp (July 2003)

Originally intended for use in a car, the Quad Car Amplifier can also be used for a wide variety of other medium power applications. As engineer Ton Giesberts explained, you can use the TDA7375A when you need a reasonable amount of audio power and only a relatively low supply voltage is available.

quad car amp

“The circuit shown here has four potentiometers to individually adjust the output levels of the amplifiers,” he noted. “In addition, all inputs have RC networks (R1/C1, etc.) to block possible RF interference. The function of R6 is to separate the grounds of the input and output stages, in order to avoid d possible ground loops that could occur with the use of multiple modules A 5W type is used for this resistor, to prevent it from going up in smoke if the ground connection of the power supply becomes loose .”

Stamp Security System (July 1997)

Elektor introduced Owen Bishop’s Stamp security system in July 1997. Built around a BASIC Stamp microcontroller, the design was intended for use in homes or offices.

Stamp Security 1997 - Engineering in July

“The system is based on the principle that the best line of defense against an intruder is strong walls with securely secured doors and windows,” Bishop explained. “The goal is to prevent the potential intruder from entering the building. Electronically, this first line of defense consists of a perimeter loop. It is a loop of wire that runs through the protected area, joining switches placed at vulnerable points.The loop includes switches at every door and window through which a person might enter the house, not to mention some of the more unlikely routes such as a trap door to the basement or a skylight on the roof.The loop covers normally all possible entrances to the basement and ground floor and all accessible entrances to upper floors Each loop entrance is protected by a normally closed switch and the switches are connected in series When a door or a window is open, even a few millimetres, the loop is broken. The control unit detects this event and triggers the alarm. If the intruder tries to cut the wires of the loop, this has so breaks the loop and triggers the alarm.”

Inexpensive transistor tester (July 1990)

In July 1990, Elektor reader J. Ruffell presented an affordable DIY design for testing transistors. The tester he developed allowed the transistor under test (TUT) to remain in the circuit, provided the circuit had relatively high resistance values. The solution was suitable for both pnp and npn transistors, and it also accepted Darlingtons.

transistor tester 1990

“The small size of the circuit board and the use of two 1.5 V batteries connected in series allow the tester to be housed in a compact housing”, explains the designer. “Connections to the TUT are made using flexible test leads terminated with small alligator clips.”

Servo motor tester (July 1986)

Elektor has always had a diverse audience with a wide variety of interests. For example, the Servo Motor Tester circuit featured in this article was intended to appeal to two different types of Elektor readers: DIY robot builders and model airplane/boat/train enthusiasts.

Great Servo Motor Tester

“The proposed servo motor test unit is, as shown in the circuit diagram, a downright simple design based on the use of 555 or 7555 type timer chips connected in a cascade arrangement which can be extended further to drive more than two servos at a time, if desired,” the author noted. “It is easy to see that the second and third stages of the circuit are identical.”

More engineering to come

Join us next month when we spotlight more classic Elektor items and projects. If you have any ideas or comments, please share your thoughts in the comments section below. The engineering continues!