DE1933701B2 - Push button preset tuning cct for superheat receiver - blocks IF amplifying stages and has automatic sharp tuning - Google Patents

Abstract

The push button preset tuning for a superheterodyne receiver uses, for example, capacity diodes for motionless tuning to the preselected broadcasting stations. The tuning selection operates by blocking one or more intermediate frequency amplifying stages which are installed in front of the regulating voltage generator for the automatic sharp tuning for the selected station. The contact for the preset tuning can be so made that it is closed during the actual movement of the selector button and operated again when the button is fully pressed in. Another possibility, enabling a simple construction to be made, is to allow the movement of the button to cause a capacitor to charge whose load voltage suppresses the I.F. stages. Discharge occurs via a resistor to release the receiver when the tuning process is finished.

Claims (1)

Claim: Circuit for silence voting in a heterodyne receiver with pushbuttons with which the receiver on predetermined transmitters, e.g. B. with capacitance diodes, is tuned and the Impressions at the same time make the breastfeeding coordination effective, and with an automatic sharp adjustment, characterized in that the breastfeeding vote by locking one or more Intermediate frequency amplifier stages, which are in front of the control voltage generator for the automatic Sharpening lie, is effected. It is known (Swiss patent specification 2 13 154), in the push button adjustment (z. B. by mechanical movement of a variable capacitor with the push button) the transmitter can be heard during Avoid traversing a frequency band by moving the pushbutton through If a switching contact is forced to close, a silent vote becomes effective, i.e. during this Time the recipient is blocked. In the indented The receiver is released again in the end position. It is also with the push-button coordination with motor known (magazine Funk-Technik 1954, p. 522 to 523) that during the motor tuning process of Recipient is blocked. A DC voltage is used as the reverse voltage for the output stage, which is generated by rectification the alternating voltage applied to part of the motor winding is obtained. It is also known (DT-AS 12 78 568), in a push button receiver during the movement of the Push-button by inevitably opening a switching contact, the automatic arming is ineffective and then only in the end position (e.g. after a brief backward movement of the pushbutton to the forward movement) to work again. The purpose of turning off the automatic Sharp tuning is to avoid that the vote by means of the automatic sharpening of a strong one Station is held before the desired weaker station is reached. The invention specified in the claim is di <> Task based in a superimposition receiver with push buttons with which the receiver to predetermined Transmitter, e.g. B. with capacitance diodes, is tuned (so-called local buttons) when you press them - Pushbuttons not only allow a breastfeeding vote to take effect, i.e. the recipient during the down-tuning to lock, but also to switch off the automatic arming, and that to simpler ones Way than previously known. One might think of it for dit -lill voting and to provide a switching contact for the automatic arming, which is activated by pushbutton are inevitably operated, but this is a cumbersome and correspondingly expensive construction required because the contacts must be actuated at the right time. It is known per se (Funk magazine 1936, pp. 137 to 140, in particular p. 139), a breastfeeding vote in the intermediate frequency part, e.g. B. by detuning an intermediate frequency stage, to be carried out, however in this proposal no automatic sharp adjustment mentioned, so that the invention is based The task at hand was not available there. The switching contact for the silent vote could be as in the known arrangement described above are forcibly closed during the movement of the pushbutton and in the depressed end position to open again. Another possibility that results in a simpler construction is to use the Closing the switch contact shortly after the start of the movement when pressed in only briefly and thereby a To let the capacitor charge, its charging savings one or more intermediate frequency stages before the Control voltage generator blocks. The capacitor slowly discharges through a resistor, so that the Receiver is released again after a predetermined time in which the voting process has ended. The use of such a time constant member is already known for a silent vote in which the styling adjustment is inevitably effected by touching the tuning button, so that the styling adjustment is retained even while the tuning button is being changed (Pit sch, textbook of the Funkempfangstechnik, Vol. II, 3rd or 4th edition, pp. 850 to 851).