Perhaps the most difficult stage in the process of creating radiokonstruktor — setting. But if you have even the simplest instrumentation, to establish any electronic device will be much easier. At least, for this job you need avometr, or simply tester. For example, very popular among ham radio uses a simple inexpensive device C-20. But the problem is, he is not entirely comfortable, and this tester is limited. So for those of you who already have such avometr, we propose to improve it by extending the limits of measurement and adding the generator probe with the test transistors.
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About code locks wrote more than once. However, most of them are difficult to repeat. Design suggested by our Bulgarian friends (the journal “Radio Television Electronics”), devoid of this shortcoming. For opening this lock simply insert the key and complete the circuit with the resistor R1 a certain value (it is mounted in the housing of the key). If the resistance will be different from that specified on the schematic, the relay does not work and the lock will not unlock.
In a previous article under the heading “electronics for beginners” (see “M-K” № 8, 1979) we understand how magnetic field is formed it Turned out that, in particular, generates supplied to the coil (solenoid) electric current. The same field with a certain force acts on it carried to the magnet. But the magnet with the same force acts on the wire, which carries current. On the phenomenon of the interaction of electric current and magnet based electric motors (electric motors).
Time relay, the readers, used in the automation devices in the workplace and at home. The device is simple in design, has small dimensions, is reliable in operation, but its main feature — a large range of exposures.
electrical Work on a modern industrial enterprise impossible without measuring instruments, many of them are very complex.
In the sixth issue of our magazine in 1974 we told about the device “Pulse” for the control of knowledge of students. Practice operating the machine created by the participants NTTM Donetsk Polytechnic Institute, as well as the feedback from readers has convinced authors of the need to improve the design.
10 years — 15 ago, the industry was widely released table lamps with fluorescent lamps, designed for a voltage of 127 V. A today 127 V network was preserved only in rare homes. It is clear that the owners of these lamps was now “tied” to expensive and bulky step-down transformers. We offer our readers we developed and tested a device that allows you to include a 127-volt lamp in the network a voltage of 220 V without the step-down transformer.
The design uses dynamic heads 0,25 GD or similar without any alterations. Ear cushions and pillows are made of a rubber sponge (you can buy in the pharmacy). For heads with a cone diameter of about 55 mm suitable sponge about the size of 155X60X35 mm. First take a piece of pressshpana or solid cardboard the size of 130X130 mm. In it cut a hole and glued it to the head (Fig. 1). Then, in the spongebob ear cushions cut out (or pluck) recess the speaker housing (Fig. 3), and the sponge-cushion (Fig. 2) make the hole oval. Its inner edge is cut from the side adjacent to the ear.
The basis of a capacitive relay — a low-power generator of high frequency such as local oscillator of a radio receiver. To the circuit L1C4 (see diagram) of the connected metal plate sensor. Approached to him the palm of the hand represents the second plate of the capacitor CD. The capacity of such a condenser is the greater, the more area it covers and the smaller the distance between them.
To the line “Start” suitable for a student with basketball ball in hands, and comes on the panel associated with the starting button of the examiner, the Machine still does not work: it can be switched on only after the button is released.