At home we often have to work with electrical tools and appliances (electric, eletronica, furnace, etc.) at a considerable distance from the outlet. And if the extension wire has a greater length (>25 m), it becomes difficult to unwind, to reel and store.
What motorist don’t care how secure your vehicle against theft or intrusion by unauthorized persons? Here, as a rule, comes to the aid of electronics. However, most electronic devices designed for protection of vehicles, often complex and expensive; moreover, they often need isolated from the body of limit switches. This limits the wide application of such “watchmen” motorists.
This device whose description was published in the journal “Funkamateur” (GDR), used in various measuring devices or equipment, where necessary intermittent light or sound alarm. Moreover, the load can be connected both with the positive and the negative pole of the power source.
The device, whose scheme is published in the journal “Popular electronics” (USA), produces a positive pulse when a sound (for example, firing of the gun) reaches the microphone B1 (see diagram). The variable resistor RZ adjust the sensitivity of the instrument, and the led V4 indicates it is turned on. Break contact S1, the finish associated with a ribbon, breaks the supply circuit of SCR V5 as soon as the athlete crosses the finish line.
The gliders don’t need to explain how important the safety speed indicator. Such a device is especially valuable for beginners: its tip in a timely manner saves the pilot the novice from fatal errors in the management of the aircraft. In hang gliding, apply sound speed indicators. Our magazine has already told about similar designs (see “M-K”, No. 3, 4, 1982, “the Speedometer on a hang glider”).
Many motorists in a hurry to install in your car the so-called device to turn off the “masses” with which, without removing the terminals, the battery easily detaches from the electrical outlet. Nothing difficult here — just need to buy at the store is one of the commercially available mechanical switches and secure it in a suitable place under the hood. Is and switch the RAD-1 remote control, which will save you from having to open the hood. It is true that the control device remains under tension, and to disable the “masses” directly from salon of the car there lay a long negative cable and drill the hole in the cowl panel.
We are talking about miniature and low-power VHF transmitter that operates at a distance of only a few tens of meters. The contractor, using a wireless microphone, can move freely around the stage and even down the hall, not being tied to a long cable with amplifying equipment. Sent by the wireless microphone signals taking on a normal VHF radio range. Then, if necessary, enhance them with powerful uzch and reproduced through loudspeakers.
Designing electronic devices on integrated circuits, radio Amateurs often use to display the information indicators IN gas-1 — IN-16. They usually feed from the mains AC voltage of 220 V or from a separate winding of the transformer. Consequently, the instrument is “tied” to the grid and they can not be used in the field.
Many tinkerers are often trying to adapt three phase electric motors for various homemade machines: grinding, drilling, and other woodworking. But here’s the problem — not everyone knows how to feed this motor from single phase.
With great interest I read in “M-To” article L. Christmas “Cellar, on the balcony.” Without a doubt, the invented by good and necessary in a city apartment unit. Writing about the atom with knowledge of the matter, as he for two consecutive years, keeping vegetables on the balcony in a similar thermostat. The results are excellent: all placed in a container in the autumn, stored until spring.