When heating a fireplace or sauna stove at a dacha with wood, the combustion process must be monitored from time to time: adding firewood, increasing draft, etc. The proposed electronic device can replace the “owner’s eye” and remind of this by signalling when the flame in the stove (firebox) diminishes. I experimented a bit and Read more…
Among elastic oscillations of air, ultrasound (from Latin ultra — beyond, more, above), inaudible to the human ear and with a lower frequency limit conventionally taken as 20 kHz, has long attracted special interest. Insects, bats, and even cetaceans make successful use of this natural gift: some for communication, others for hunting, others for locating Read more…
Among self-defense devices, electroshock units (ESU) are far from the least notable, especially in terms of psychological impact on attackers. They are, however, quite costly, which motivates radio amateurs to build homemade analogues (see, for example, the detailed article on this in issue No. 5’99 of “Modelist-Konstruktor” magazine). Without claiming to be highly original or Read more…
The metal detector I developed has not yet been used in peacekeeping operations to detect and neutralize minefields, nor in large-scale geological or archaeological surveys. Designed not for professionals, but for amateurs whose desire to “look underground” can be satisfied by a design with the parameters given in the table, it is an improved version Read more…
When lighting fixtures and electricity were cheap, the question of a thrifty approach to choosing lighting for stairwells was not seriously considered by anyone. But life has taught everyone to count every penny, so there’s no need to convince anyone about the advisability of using an automatic stairwell and corridor lighting switch (ASCLS). The question Read more…
If a radio amateur’s inventory is burdened by a low-power portable radio station (or a set of two stations) designed for communication in the civilian range of 26.9 — 27.2 MHz, I propose a way to make good use of them. Often, a radio amateur is simultaneously a car owner and a dacha owner, who, Read more…
I propose a design for a gasoline-electric unit (GEU) “Firefly”, designed for charging batteries, powering lighting lamps and other DC consumers at 12 V. I developed this unit three years ago at the request of my friend, an avid hunter and fisherman. Since then, “Firefly” has been serving reliably, lighting his taiga cabin and helping Read more…
One of the inconveniences in the design of many cars is that the interior light immediately turns off when the doors are closed. There are, of course, special devices that delay switching off the lighting for 5–15 seconds, allowing the driver to check the dashboard, the controls, and insert the ignition key. However, such solutions Read more…
The metal detector I designed operates on the beat frequency principle, which arises from the difference in oscillations between the reference and the tunable oscillators (typically the 5th–10th harmonic, whichever is closest in frequency). This design allows the detector’s sensitivity to reach a level where it can detect, for example, a five-kopeck coin buried 10 Read more…
Many families today live in multi-storey buildings and use household washing machines. Anyone who has ever connected such a machine (to the electrical panel and plumbing system) knows how important both of these operations are. In particular, if the drain hose is poorly connected to the apartment’s fan pipes, a leak may occur. This can Read more…
