DE2339850A1 - Small sender for carrier frequency A.F. signals transmission - transmits over short distances and has device for its external control - Google Patents

Abstract

It uses either d.c. voltage for the sender generated by a power pack supplied directly with the AF signal at the socket for external loudspeaker or headphones, or supplied by a battery with an intermediate automatic switch between battery and sender, controlled by the AF signal. The battery is connected to the sender when the AF signal voltage exceeds a minimum value, and this connection is broken after a delay of e.g. a minute after the AF signal is switched off. The AF signal collected from the socket for external loudspeaker or headphones is also used for the sender modulation. The storage time is at least several seconds. The power pack consists of a transformer, a rectifier and a capacitor, and a stabilisation circuit is provided between this power pack output and sender. The automatic switch consists of a switching transistor whose switching state depends on a transistor rectifier.

Description

Arrangement for the external operation of a small transmitter for the carrier-frequency transmission of audio signals over short distances.

In the main application no, P 23 07 6J2.6 was an arrangement for carrier-frequency Transmission of sound signals over short distances is the subject of the invention. There it was first announced that the transmitter was in the television receiver radio receiver or stereo amplifier or tape recorder etc. is built and is fed from the DC voltage source available there «

With the serial use of such wireless transmission systems arises, especially when retrofitting devices of the above type, the problem of the power supply of the transmitter after one in this Case without an intervention to be carried out by a specialist in the relevant receiving device, whose audio signal is to be transmitted wirelessly, wants to get along "

The present invention relates to an arrangement for external operation a small transmitter for the carrier-frequency transmission of audio signals via short distances, characterized by the use of one of the two Measures :

Obtaining the operating DC voltage for the transmitter with the help of a "Nets device ^w , which is fed directly from the audio signal available at the socket for external speakers or headphones;

Obtaining the DC operating voltage for the transmitter from a battery Intermediate switching of an automatic switch-on controlled by the acoustic signal Battery and transmitter, on the one hand, when a minimum voltage is exceeded of the sound signal connects the transmitter to the battery and on the other hand delays it, E.g. within a minute, after switching off the acoustic signal, this connection between the transmitter and the battery is disconnected.

According to the invention, naoh ¥ lg. 1 the audio signal generated by the receiving device (i) is taken from the socket (2} 3) for external loudspeakers or headphones and connected via a two-wire line (4) to the wires (5; 6) which, due to the low connection resistance of approx. 4-8 Whether »does not have to be shielded,

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Via a series resistor (7), which is supposed to reduce the influence of distortions in the rectifier circuit on the low-frequency signal, to an " ¹¹ power supply unit".

This "power supply unit" consists of a transformer with the primary winding (8) and the secondary winding (9) a rectifier (1O) and a charging terminal

, _% .10 000 _x

capacitor (11), the capacity of which must be so large (e.g. ^ uP) that the corresponding the temporal distribution of the sound signal piano points and pauses in speaking are bridged by a sufficiently large time constant of at least several seconds can be.

In order to reduce the fluctuations in spite of this high time constant occurring with this the power supply ^w "obtained DC voltage in the order of sound for example about 5 - 40 V is achieved according to a stabilization circuit between the ^m power supply" is provided and the transmitter circuit.

This stabilization circuit consists of a transistor (14) as a variety Series resistance, the base voltage of which is determined by a Zener diode (13) » which is fed via the resistor (12) to a defined value of E.g. 12 V is held as long as the DC voltage on the capacitor (11) is greater than this value.

This stabilization circuit makes it possible to make the "power supply" more powerful to control and thereby to raise the minimum signals and in connection with the storage effect of the charge capacitor (11) to better bridge breaks in speech without an economical overload of the transmitter or too great a load Risking transmission power.

The circuit arrangement according to Fig. 1 allows in connection ^ !, t of the series resistor (7) the distortions according to the invention in the voltage peaks, which are generated by the rectifier (io) caused, sufficiently reduced, a simultaneous use of this tone-free signal voltage u ~ -, for modulation of the transmitter.

Since this audio signal voltage is on the order of several volts, this voltage is sufficient for direct modulation of the transmitter, e.g. to control a capacitance-variation diode via a pre-emphasis network.

This rigid coupling of "butcher" is made in accordance with the invention. and modulation, a simple setting that can be used by any layperson optimal audio frequency voltage u ™ enables

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by turning the volume control of the

Device (1) is set so that just no audible distortion

appear.

Another part of the gate that decouples the audio signal from the output

socket (2; 5) is that the sound image through the "treble or -

Depth regulator "can be influenced as desired« In Fig «2 the circuit of an automatic switch-on is shown, which for the Case of battery operation of the transmitter (instead of the one shown in FIG

ⁿ power supply ^w ) should be used «

Here too, according to the invention, the output socket (2} j) (Fig. 1) of the Device (1) (Fig. 1) the audio signal u ^ via a cable (4) (Fig. 1)

taken

This signal reaches the base of the transistor (18) via the capacitor (16)

and opens this transistor, provided that the low-frequency voltage is at least e.g. 1.2 V _eg reached

The charge reversal diode (17) prevents undesired charging of the capacitor (16)

and supports the intended opening process of the transistor (18) _#

The emitter of the transistor (18) is at the plus potential of the battery (I5) t

so that when the transistor (18) is open, the storage capacitor (I9) is close to this battery voltage is charged.

Then over the resistor (20) the transistor (21) opened, which in turn over

the resistor (22) controls the transistor (23) acting as a switch and thus causes the operating voltage U to be switched on.

This operating voltage corresponds to the saturation voltage (about 0.3V)

of the transistor of the battery voltage U_ which is open here

Through this switch-on autosnatik according to the invention, the extrea stroeeparend

(Rühestroaauf would take less than 1 microampere) is executed, the transmitter only when there is a sound signal switched on and thus the load on the

Battery reduced to a minimum » The storage time of the capacitor (19) and the resistor (20) Speioher member should be chosen in the order of a minute «ao dal Spreohpausen and piano parts can be bridged reliably. Bann this automatic switches the transmitter about one minute after stopping the Device (1) (Fig. 1) automatically.

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Claims (6)

Claims. 1. Arrangement for the external operation of a small transmitter for the carrier frequency Transmission of sound signals over short distances - ^ by the application one of the two measures: marked a) Obtaining the DC operating voltage for the transmitter with the help of a ^w power supply unit ", which is fed directly from the audio signal available at the socket for external loudspeakers or headphone, b) Obtaining the DC operating voltage for the transmitter from a battery with the interposition of an automatic switch-on controlled by the acoustic signal between the battery and the transmitter, which on the one hand occurs when the a minimum voltage of the audio signal connects the transmitter to the battery and, on the other hand, delayed, e.g. within one minute, after switching off the sound signal disconnects this connection between the transmitter and the battery " 2. Arrangement according to claim 1, characterized in that that of the socket The audio signal taken from the external loudspeakers or headphones is used to modulate the transmitter at the same time. 3. Arrangement according to claim 1, characterized in that the storage time is at least several seconds. 4 · Arrangement according to claim 1a, characterized in that the "power supply unit" from a transformer (8; 9), a rectifier (1O) and a charging capacitor (11) consists. 5. Arrangement according to claim 4, characterized in that a stabilization circuit (12; 13 »14) between the output of this power supply unit and the Transmitter is switched. 6. Arrangement according to claim 1b _f, characterized in that the automatic switch-on consists of a transistor (23) acting as a switch, the switching state of which is via the transistor (21) from the de «sound signal with the aid of the transistor (18) operated as a rectifier obtained and stored in the capacitor (19) is controlled automatically * 509813/0399