AUTOMATIC ACTIVATION OF PC SPEAKERS

As you know, speaker of the personal computer (PC) it is necessary to include separately. If they are installed at some distance from the operator, this situation is hardly comfortable, especially if the user wishes to view on a DVD movie recorder or any other video, accompanied by sound effects.

How to make the speakers turn on automatically with the activation of a PC?

The simple solution suggests itself — to connect PC and speakers into a single electrical loop filter, for example SVEN OPTIMA, and run all the equipment a single switch on the body of the tee. But there is another more “elegant” way. For this purpose the author has developed a simple scheme is shown in Fig.

The simplest way to automate the inclusion of speakers of the acoustic system (as) PC during operation of the system unit — use the standard USB bus.

Modern PCs allow you to connect to the USB bus (in the family of Pentium-4 on the back panel of the system unit is not less than six connectors for connecting the interface device with USB port) variety of peripherals — scanners, WEB-cameras, printers, digital cameras and other peripheral devices.

For speakers that do not feature automatic inclusion together with the activation system unit of the PC (and there are now a majority in the price range up to 1000 RUB.) will be useful for the proposed revision. Implement it capable of any, even slightly familiar with a soldering iron and basic electrical engineering.

The knot complement is a transistor switch (amplifier current to the compound transistor VT1 — VT2), which is controlled by the positive potential from the connector of the USB device is +5 V. This voltage is removed with the connecting cable (of any configuration of the USB — if only it had a voltage of +5 V); in the author’s version used a USB connector with built-in led illumination. The control signal can take directly from the motherboard of the PC, but not to entangle the system unit “beard” of the wires, you can use the control signal from any of connecting USB cables going to the scanner, WEB camera and other peripheral devices.

Circuit diagram of automatic transfer switch speaker for PC simultaneously with turning on of the system unit

Circuit diagram of automatic transfer switch speaker for PC simultaneously with turning on the system unit.

To adapt to the host control speakers speakers PC USB connector open (dismantle) and connect to terminals 1 and 4 (respectively presented) conductors connecting the transistor switch VT1 — VT2 and column as PK. Recently, in retail there are USB connectors with built-in led backlight in a transparent enclosure. In this embodiment, finding contacts for additional equipment is greatly simplified.

Transistor switch with the features of “obiski” is placed inside the PC case. Connections are made flexible shielded wire. But if the distance from the speaker to the PC USB connector does not exceed 1 m, connections can be run unshielded wire type MGTF-… MNIF 0,6-0,8.

When you turn on the system unit control signal with an amplitude of +5 volts through a rectifier diode VD1 is supplied to the amplifier transistor VT1, VT2. In the absence of these in the diagram transistors can be implemented the current key on the other silicon transistors with high gain, for example, КТ34В, КТ817Б (n-p-n conductivity). Diode VD1 can be replaced KD522, Д310, Д220 with any alphabetic index. Oxide capacitors C1 and C2, the smoothing of ripples on diet, type K50-24, K50-35 or similar.

When you turn off the system unit control signal from the USB connector disappears, and speakers as the PC automatically disabled.

Node does not require configuration and serviceable details starts to work reliably and immediately. PCB was not designed, as all the small elements are mounted on a regular printed circuit Board with speaker method surface mounting.

USB connection to PC does not adversely impact on the sound parameters and the power amplifier of the sound card and PC speakers. Transistor VT2 may be used without heat sink plate.

A. KASHKAROV, St. Petersburg

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