Busy with household chores or interesting conversation, we forget, for example, on a boiling kettle. Time to remind him maybe a simple buzzer. However, the oscillators sound frequency (e.g. multivibrators) based on transistor logic or integrated circuits do not always meet their creators. The simplest devices give a smooth tone, barely visible against the background of everyday noise, and sudden and loud “beep-beep” of a more complex designs can scare.
We offer homemade household heat stabilizer can be used in incubators, dryers, fruit, mini-greenhouses etc. From existing analogues it is original schematic construction, maintaining the temperature with an accuracy of ±0.1 °C, tolerance with fluctuations in the AC 160 to 240 V, and can operate from a DC source with voltage up to 310 V. the Power regulated heater element can reach 750 watts.
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needed for anyone who is keen on constructing of measuring equipment and equipment for radio control models. Simple circuit universal wavemeter, shown in figure, is a conventional crystal radio set, whose output is headphones included the arrow measuring device ИП1 with the DC amplifier transistor T1.
In the old days, when required to perform switching in the electric circuits when the voltage rises to a certain threshold, resorted to the use of polarized electromagnetic relay. However, the substantial size and weight, lack of reliability of the kinematics and contact pairs severely limited the use of these devices. Now in their place came a miniature non-contact thingies called discs. This four-layer semiconductor diodes whose structure is like a two transistor: p-n-p and n-p-n type, with the base of one is connected to the collector of the second, forming the internal positive feedback (Fig. 1).
“For the treatment of infield has decided to replace the tiller internal combustion engine electric. Already got polutoraterabaytny the motor. But it is three phase. How to connect to the network, where only one phase and “my best”?
Viewers living in areas of new buildings high-rise buildings and besides, near the television station, I recommend to get a homemade antenna-loop. It works reliably even when the so-called “strong reflections” television signals and preventing screen ghosting of the image.
Hams know how sometimes when soldering they do not have a third hand to fix a small detail. At the time it was proposed many devices that can help in such a situation (see, for example, the magazine “modelist-Konstruktor” No. 10’1996). In particular, I use a fixture, which is made in just a few seconds.
Informing about the occurrence of an event, people often use sound signals. Usually they have the character of a continuous sound “one note” annoying “beep-beep” or howling siren with a periodically varying frequency. Generators of electric vibrations, producing these signals is also straightforward. They are based on one-two multivibrators, which makes the structure very simple, accessible to even beginners repetition hams.
Who used a portable transistor radio, know how, over time, decrease the sensitivity and loudness of the radio, begins to “float” the rate of advance of the tape in the music player…