This security alarm device (SAD) is intended for automatic sounding of an alarm signal (electric bell) in case of unauthorized entry of outsiders into a protected premises — an apartment, a country house, or a garage. It features higher noise immunity and the absence of false alarms. The device is powered by a 12-volt battery Read more…
Many people keep various pets, and spending time with them brings plenty of pleasant moments to both children and adults. However, there are also animals that constantly live near humans and often visit their homes (for example, mice and rats). Yet they are uninvited and even harmful guests, since they are considered (and, probably, not Read more…
Having read in issue No. 1 of “M-K” for 1989 a description of an electronic vehicle ground cut-out, I decided to use it as a simple anti-theft device. However, when the toggle switch is replaced with a push-button (as recommended by the designer V. Arapov) or with a reed switch, a highly undesirable effect occurs: Read more…
Security systems are a rapidly developing area of modern electronics. A huge number of various circuits and designs have been published that anyone who has held a soldering iron in their hands at least a couple of times can build. For example, “electronic guards” can warn of an intruder entering a room or signal the Read more…
Explosions and fires caused by gas leaks are, unfortunately, not uncommon. While giving due credit to the work of administrative bodies and emergency services, radio amateur designers can also do something themselves to minimize this danger. However, in the field of gas monitoring there are almost no simple, reproducible devices, or they are unreasonably expensive. Read more…
It is hard for an outsider to understand anglers who sit all day, as if hypnotized, with a fishing rod, never taking their eyes off the float. Of course, patience eventually runs out even for the most devoted, especially if the fish does not often reward them with bites. That is why many experiment, trying Read more…
When I needed a megaphone, I looked at the prices of industrial Chinese products: as it turned out, they cost from $45 to $235, and I decided that I could assemble a similar device with my own hands in a couple of hours. A megaphone (or loudspeaker), the electrical circuit of which I recommend and Read more…
In large apartments and private houses, it is difficult in the evening and at night to walk along dark corridors or stairs and find the switch by touch to turn on the lighting. There is also an alternative — to buy autonomous “soft light” fixtures; they can be installed anywhere convenient for the owner. However, Read more…
I offer readers of our favorite magazine an automatic plant watering and spraying system of my own design, which has proven itself both indoors and in a greenhouse, winter garden, and flower bed. It consists of two interconnected subsystems: “sensor — water supply” (fig. 1) and an electronic control unit (fig. 2). While the first Read more…
Smartphones look similar on the outside, but the real changes are inside. iPhone 17 teardown — a journey into Apple’s engineering kitchen. Engineers worked hard: fixed old problems, made bold moves. Teardowns help understand “how it’s made” — how long the device will last, how it will survive drops, how painful battery replacement will be. Read more…
