VCR attachment. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Телевидение
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The set-top box is designed to broadcast video programs from a VCR within the apartment. It can be used, for example, to send cartoons to a children's room, or in stores to display one picture on all screens.
The board for converting video and audio signals into a modulated RF signal from the Dendy children's gaming computer (hereinafter referred to as the modulator) is taken as the basis. It is no secret that such computers often fail, and for many they either lie idle or are disassembled for details. The modulator itself rarely fails, except that the stabilizer chip burns out, but it is not used in the prefix described below.
Figure 1 shows the part of the board to be reworked (dotted). In the indicated place, all radio components and the connector should be removed, and it should be cleaned of current-carrying tracks, which is easily done with a soldering iron and tweezers.
Ris.1
Then, two 5 uF capacitors and two 33 kΩ variable resistors are installed in this place, as shown in Fig. 2. A 1000 uF x 16 V capacitor is connected in parallel with the power supply. If the "video" and "audio" connectors on this board are enabled (sometimes not), you should cut the tracks coming from them. The RF output jack (not shown in the figure) should be unsoldered, and the output itself should be connected with an ordinary mounting wire to an antenna, which can be any telescopic antenna from industrial radios. The modulator is powered by any 5 ... 10 V power source, for example, an adapter plug from a calculator. Due to the fact that voltage is applied to the circuit without a stabilizer, the transmission range will slightly increase.
Ris.2
Reception is carried out on a conventional indoor antenna by almost any TV, because. The device operates in the meter range. Setting up the transmitter comes down to setting the signal levels with variable resistors for the best image and sound quality.
Attention! It is not recommended to make such a transmitter if there is a TV broadcast in your area on the same channel on which the modulator operates.
Author: A. Lysunets, v. Vozzhaevka, Amur Region; Publication: N. Bolshakov, rf.atnn.ru
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