Handy Test Light (v1)
Get ready to make a high-resistance continuity tester pen that runs on a pair of common 1.5V AA batteries. This design is based on an idea from a Chinese website but with a few modifications. […]
6V Battery Guard Relay Module
Many of the newer robotic toys for kids now use 1.5V AA or AAA batteries as the power source. And it is a common practice to wire them in series to get a healthy 6VDC […]
CD4541 Programmable Timer IC Cheat Sheet
Today we are going to inspect the CD4541B CMOS programmable timer IC. The CD4541B programmable timer chip has a 16-stage binary counter, an integrated oscillator for use with an external capacitor and two resistors, output […]
An Old School Transistor Shunt Regulator
I had some time to kill on a recent rainy monsoon night, so I decided to brush up on my knowledge of basic shunt regulators. Luckily, I had a lot of BJTs and Zener diodes […]
5V Microcontroller Power Rail Guard
This 5V microcontroller power rail guard is a quite simple solution to add an overvoltage protection (OVP) mechanism between the 5VDC power source and your microcontroller board. In short, this little design uses a Zener […]
Doorbell Sensor IoT Module (v1)
In this post, I will attempt to share the design idea of a doorbell sensor that can be build using just a handful of inexpensive and easily available electronics components. When cleverly integrated into your […]
4V SLA Battery Charger
Pretty little 4V Sealed Lead Acid (SLA) or Sealed Maintenance Free (SMF) batteries are widely used in portable electronic gadgets such as mosquito bats, kitchen scales, healthcare instruments, etc. The most common 4V SLA rechargeable […]
Poor man’s AC230V Smart Plug v1
Recently I have received a few messages from a follower who is interested in making a simple relay box that will help him operate some regular electrical devices using the control signal from a common […]
Inverter Crystal Oscillators & A Half-Baked Project
This post describes the construction of basic crystal oscillator. The key parts in the experimental setup are a KDS4.000 quartz crystal (4.000MHz) and a SN74HC04N hex inverter IC. It should be easy to use an […]
Window Comparator Revisited
Circuit configuration of a Window Comparator usually consists of a pair of inverting and non-inverting voltage comparators in which the output indicates whether an input signal is within a voltage range defined by two different […]