HEAR COMES THE TRAIN!

HEAR COMES THE TRAIN!Many readers of the magazine are building all kinds of model planes, ships, trains, cars and other equipment. However, for greater affinity with their prototypes it is desirable to “voice”, which will give them even greater appeal. Recall, for example, sounded like a train. First heard a gradually increasing noise of a train, then near the station he blows his whistle to his approximation, and stood, and noisily blowing off steam, making a sound like “poof poof poof”. Before leaving the station bell sounds, and the locomotive gives a farewell whistle before the journey.

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SCREW ON THE CONTROL

SCREW CONTROLWhen developing propeller systems snowmobiles, trikes, aircraft and model aircraft designer is required to know the exact values of some parameters. And most importantly — the frequency of rotation of the propeller. It is necessary and when the force of the engines, and the selection of the propeller. The frequency of rotation is also one of the main parameters in the process of operation of the motor: the value of this parameter is possible to objectively judge the reliability of the engine.

THE LIGHT WILL ACTIVATE THE SIREN

LIGHT WILL ACTIVATE THE SIREN

The proposed German magazine “Funkamateur” light relay is activated when light falls on the photoresistor R1 (see diagram) — when this occurs, a loud siren sound. Transistors VT1, VT2 equivalent odnoimennogo of the transistor included under the circuit of the sawtooth generator. The oscillator frequency is determined by the capacitance of the capacitor C1, the internal resistance of the photoresistor R1 and the resistor R2. Transistors VT3, VT4 included in the Darlington circuit, perform the function of the AF amplifier. It is possible to replace. Photoresistor — any domestic; transistors: VT1 – КТ3107, KT361, КТ203; VT2, VT3 blocking – KT315, КТ312; VТ4 – КТ503, КТ603, КТ815 with any alphabetic indexes.

AT THE DOOR BARKS… A TAPE RECORDER

AT THE DOOR BARKS... RECORDERIn these troubled and difficult time when the crime situation every year more complicated, the important importance of watchdog and signaling device that protects property from encroachment by criminal elements. Among these developments, I have designed instrument, to collect which can anyone, even a novice radio Amateur. Using as actuator recorder of any type, on a looped tape which recorded tigrama barking dog, it simulates presence in the building watchdog. And the electronics triggering happens at the moment of approach or touch of a human hand to the castle.

CAN BE BRIGHT, CAN FAINTLY

CAN-BRIGHT, CAN FAINTLYWant to improve your capital on the lamp. Say equip it with a dimmer glow (which is especially important when watching television), and compactly built-in outlet, resulting in the lighting device have an additional opportunity to serve as a kind of extension! Then feel free to tackle The more scarce parts and assemblies necessary. As, however, and a solid knowledge-experience in the field of electrical and radio engineering.

THE REFEREE SIGNALS

REFEREE SIGNALSDo you think what is common between math and electronics? Readers familiar with digital technology, recall that the mathematical laws of Boolean algebra the basis for the action of logic circuits. But that’s not all. It turns out that in mathematics, and electronics often use this concept as a comparison. But if you have to compare them with other numeric values, in electronics there is a comparison of the electrical signals. To perform such operations even created special devices — Comparators.

ANTI-THEFT – IN 5 MINUTES

ANTI-THEFT ALARM FOR 5 MINUTESAfter reading No. 1 “M-K” for the year 1989 description electronic switch-off “weight” of the car, decided to use it as a simple anti-theft tool. However, the replacement of toggle on the button (as advised by the project author V. Arapov) or reed switch occurs very undesirable moment when the voltage produced by the generator will be equal to the battery voltage, the transistor closes. And in the future on-Board vehicle network will be powered by only one generator. And as for fuel economy the engine is regulated to the minimum idling speed, the voltage generated by the generator in this mode, will be low. Therefore, at the moment of starting off (as in a “weak” generator, and when the light is turned on) the engine may stall. But the main danger occurs when emergency braking, as when the engine stops, the on-Board system is de-energized and the brake lights do not burn!