THE MOTOR IN THE ROLE OF A TESTERAmong the devices that are used to check (continuity) of electrical circuits, not take samples. They are simple in design and application. The probe is an indicator, in series with which is connected, as a rule, galvanic cell (battery), current-limiting resistance and two testers. Touching the probes on different portions of the circuit, checks the condition of all its parts and proper connections.

But in addition to galvanic cells, and other known sources of supply. Why not apply them in the design of the probe and to make the device, for example operating on the basis of electromagnetic induction.

The prospects of this idea are convinced, collecting scheme, much like the school’s demonstration of experience in the study of the laws of Faraday. Source of electricity was multiturn coil (series-connected windings of polarized relay of the RP-4) introduced into the regular “band” magnet 3x3x40, the end of which is connected to a steel spring. As an indicator coming from the led with a nominal current of 20 mA glow. Probes were two cut flexible circuit wire in vinyl insulation, equipped with clips of type “crocodile”.

Of course: if you click on the core-a magnet (or a bit to pull out of the coil), and then let go, the spring will return the electromagnetic system to the original position. In the coils there will be induced EMF proportional to rate of change of magnetic flux. When connecting a probe with the same power source, e.g., a good diode svetaine-cator light will illuminate only in a single polarity of the p-R transition. If the flash is in both polarities, then check the diode is “punched”. When outbreaks no with one polarity, means there is an internal open in the studied semiconductor device.


Schematic and design of the probe, which in the role of the power source is a... the motor from a broken toy or electrified cassette recorder

Schematic and design of the probe, which in the role of the power source is a… the motor from a broken toy or electrified cassette recorder:

1 — transparent plastic case (modified from a shampoo bottle); 2 — terminal (stud M4 nuts, 2 sets.); 3 — microelectronical; 4 — led; 5 — output with clamp type “crocodile” (2 PCs.)

In the same way checked f-R transitions from the power transistors. Given that the collector in such a semiconductor triode is connected to the body, you can get the Pinout, not having at hand the appropriate directory.

Make sure of health considered the above design, began to experiment with other options a homemade probe, instead of embedding electrochemical cells “unconventional sources of supply” type of phone earpiece TK-67-NT or dynamics 1ГД-28. And made sure that when tapped on the diffuser in the audio coils of such electromagnetic systems EMF occurs, sufficient for the led test electrical circuits.

But the easiest way to perform file transfer probe, in which the power supply uses a standard microelectromechanical (e.g., electrified toys or cassette recorder), an employee of the now generator. In addition, this device distinguishes itself from other simplicity, reliability and originality of the design. Especially if the hull is… the “upgraded” plastic bottle for shampoo or other household chemicals (see figure). For probe only need neck from the container with a transparent Central part, in which are inserted a series-connected led and the power source—microelectromechanical generator, fixed studs with nuts terminals. To them and fasten the flexible leads having clips of type “crocodile” to connect to check the area of electrical circuits. If the circuit tests normal, then when turning generator shaft having flash led, which can be seen even peripheral vision.





In conclusion, a little advice to anyone who decides to make this probe with led indicator and microelectromechanical generator is a galvanic power source. At the stage of prototyping should ensure the correct setting of the polarity of the led anode to the “positive” output of the Converter of mechanical energy (rotation of the rotor in the usual direction, for example, clockwise) into electricity. The shaft it is desirable to provide a ribbed tip which can accommodate a screw cap from a tube of toothpaste.

S. LEVCHENKO, St. Petersburg

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