(Continued. Beginning in № 9’01). To making a universal charging apparatus, it is recommended to proceed only after at hand will be all you need, including tools and supplies. Case size mm 300x200x200 taken or prepared, as the front panel (300×200 mm), handmade. Transformer power 250 VA, is wound on the magnetic core SHL 50×32 mm (for calculations it is more convenient to use the units of measurement universally accepted Amateur practice, when the cross section of the magnetic circuit is expressed in cm2; in relation to the SHL package recommended core 17.5 cm2). If the core is W-shaped, the sectional area needs to be 1.4 times more, that is, 24.5 cm2.
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Generators of low frequency oscillations, as is known, can be used as a caretaker: intermittent loud noises warn of the approach of a stranger. On the same principle and made our “Keeper”. It is assembled on the transistor T1 and the transformer TR1 (Fig. 1). Load — the loudspeaker TP1. The chain of positive feedback R1, R2, R3, R4, C1 provides periodic self-excitation of the generator.
I remember a few years ago in the journal “modelist-Konstruktor” there is the material possibility of measuring electrical capacitance using a PC “Specialist”. Then published the program in machine code that allows with reasonable accuracy to determine the values of capacitors in the range of 0.1—1000 UF, and later version of it written in forth language, for which the wording, of course, a huge thank you!
“Dear edition! In rooms 11 and 12 your magazine from 1973 published a description of the guitar in Leningrad designers and lovers Guzina O. and D. Med, hex. The tool we liked.
The process of establishing electronic circuits the most exciting and interesting, but also the longest, sometimes bringing a lot of grief for Amateurs due to the lack of reliable power supply. After all, the battery or the battery do not serve indefinitely — they are discharged. Changes frequently and the line voltage. And each scheme is designed for a specific voltage. Changing it degrades the operation of the entire electronic device.
Without pretending to any special built in circuitry to use a more graceful version of an intercom that can be used as an intercom system in the private house or in the country. The design is simple and available for self-production, even a novice radio enthusiast. In standby mode the device does not consume battery power, but is always ready to work: just touch the button and — please say! Working on the second set you will certainly hear.
“What to replace the gauge?” — this question often arose during the meeting with an interesting measurement scheme. Ohmmeter, voltmeter, test transistors — these devices are difficult to imagine without a milliammeter. Nevertheless, this instrumentation can work without a dial indicator. This is easy to see, collecting scheme, in which the role of the indicator does… sound generator.
A lighter, a diagram is shown in the drawing, is intended for gas stoves. It is reliable, comfortable and safe. The device is a transistor blocking oscillator, powered by dry batteries with a voltage of SV.
The convenience of wireless remote control (RC) is undeniable. You can use them, without getting up, and the most interesting channel to enable, and the hardware on it to adjust according to the individual characteristics of perception.