Stepped Timer (ART726E)
In this article, we will describe an interesting timer that provides timing indications in several stages of a given interval and, at the end, activates a relay, which can either power an external load or turn it off. By using a voltage comparator, we can achieve timings in a range that extends up to a few minutes, leading to a wide range of uses for the device.
Electronic Circuit Breaker (ART727E)
This circuit can serve as protection for power supplies and even loads in case of a short circuit, because when this occurs, the power supply is automatically cut off. If the short circuit is broken, the power supply is automatically restored. The circuit operates with power supplies up to 12 V and a current of 1 A.
Electronic Cockroach Killer (ART649E)
During hot weather, cockroaches proliferate in certain places, attacking various types of food, especially sweet ones. An environmentally friendly way to eliminate these insects is to use an electronic trap, which kills them without the use of chemicals. The design we describe in this article uses the same principle as the fly traps we see in the meat sections of supermarkets and other establishments: a high-voltage shock.
Two Projects with Ceramic Transducers (ART647E)
Do you know what a ceramic transducer is? Do you know its purpose or how it works? For some, this name might mean something quite critical and unfamiliar; for others, it's just another name for another component. Below, you will learn what a ceramic transducer is and how it works, as well as the opportunity to create two interesting assemblies with it: a police siren and a pressure or knock alarm.
Digital Capacitor (ART644E)
In Issue No. 2, 182, we published the design for a Digital Counter Module that, as mentioned in the article, would serve a multitude of practical applications. Among the applications suggested in that issue, we already published a 32MHz Digital Frequency Counter, a Digital Stopwatch, an Optical Counter, and an Electronic Sorter. Now it is the turn of the Digital Capacitor, a very useful bench top instrument for reading capacitances between 100pF and 10,000pF. Simple to assemble and using common components, the accuracy of the readings depends solely on the adjustments made by the assembler.
Designing and Assembling Transformerless Power Supplies (ART604E)
Transformerless power supplies, or FAST for short, or simply transformer less power supplies, are very useful in low-consumption projects that must be connected to the power supply network, as they eliminate the need for an expensive and bulky component, the power supply transformer. How to design and assemble this type of source is what we will see in this article, which is very useful for those who need sources of up to 12 V with maximum output currents of around 50 mA.
