OVERLOAD PROTECTION CIRCUIT FOR A LOUDSPEAKER ARRANGEMENT

Loudspeaker arrangements, among them both a single loudspeaker and a loudspeaker combination are to be understood, are construction dependently only limited electrically loadable. With Ano conclusion at sources of audio frequency of higher achievement threatens from there the destruction of individual and/or all systems of the Lantsprecheranordnung. s acquaintance electrical safety devices, which are destroyed with a certain rated current, and the current supply thereby interrupt, are suitable as overload protection for loudspeakers and/or loudspeaker combinations less, since they exhibit a high failure frequency because of the pulse-type character of the fed audio frequency signal. Overload protection circuits for a loudspeaker arrangement, the dle Lautsprecheranordnun without the above, by impu] the sförmige signal conditioned Ausfal] häufigkait, before an overloading, is acquaintance protects. Thus the DE-OS 2448506 e.g. shows a Überlastschutz°Schaltung, which lowers the supplied audio frequency achievement as a function of the temperature of the Lautspreeherspule. A such circuit possesses however the disadvantage that them are relatively slow-acting due to the relatively slowly running Wärmeausgleichsis procedures, i.e. retarded on the Toufrequenzsignale responds, whereby the loudspeaker coil is relatively strongly loaded every now and then. By the GB-PS No. 1407824 a circuit is become known, which avoids these disadvantages. The Fig.1 of this writing shows an overload protection circuit for a loudspeaker arrangement, which is turned on to a source of audio frequency, with a lining up attitude of a diode, a BegrenzunEswiderstandes and a condenser, which lie parallel to the exit of the source of audio frequency and with a relay circuit, which interrupts the connection of the loudspeaker arrangement as a function of the tension at the condenser and preferably inserts thereby a pre-resistor. This circuit responds very fast, so that the coil is practically not loaded. A loudspeaker arrangement provided with this circuit can be operated thereby at any amplifier beüebig high and/or higher Verstärkerleistunff than the indicated load rating. This circuit represents thus a automatic, self-healing electrical and/or electronic protection as overload protection for a loudspeaker arrangement. The invention goes out with these overload protection Schaltüng. You are the basis the task to improve the well-known circuit in such a way that the overload Anspreehpunkt is more defined and further the restarting delay is ert after responding to overload vergrSf. The solution of this task succeeds in accordance with the invention thus that the relay circuit lies in the post office circle of a “transistor, in whose Anstenerkreis parallel to the condenser and defining resistor of switched resistance Spannungstefler lies, whereby a resistance of the voltage divider a Zenerdioäe is parallel switched, and that of switches 3s operated of the Relaisschalmnff is intended, which connects the condenser in the normal operation condition with the defining resistor and scolded in the case of overload the condenser paranel for the other resistance of the voltage divider. The point, at which the transistor and concomitantly the Relaisschaltunff in the upper load case respond, lets itself adjust relatively defined. Also the restarting delay is relatively high by an appropriate calculation of the condenser bypass resistor, i.e. a “healing” of the available, as a kind protection working overload protection circuit is possible practically only by taking the input voltage away, whereby the operator becomes “educated” quasi to stop the overload range not. Appropriately the relay circuit, ausgebüdet as elektromagneüsches relay (s), lies in the emitter circle of the transistor (Tr). In the case of a such arrangement favorable conditions result regarding the 4s impedance match. A Weiterbüdung of the invention consists of that parallel to relay (s) an auxiliary condenser (C) is switched. This auxiliary condenser supports the switch-off delay, which is planned by the ParaUeischaltung of the input condenser with a resistance of the voltage divider. A further arrangement of the invention plans that the resistances (R4, R3) of the Spanuungsteilers it is so adjustable. By this measure both the Ansprechpunkt and the point of declivity time are adjustable. After a further out-arranging characteristic the circuit is so met that the switch (S1) consists of a two-way contact of the electromagnetic relay (s). During a such circuit the expenditure is relatively small. By at-PS Nr.294214 a protective circuit for a loudspeaker arrangement is become known, which transistors contains, which operate an electronic relay circuit dependent on the supplied audio frequency achievement, however is developed this circuit in the heading for circle of the relay circuit completely differently than that after the invention. It does not contain also the substantial on the s Schaltzusmnd change-over dependent of the relay circuit on elements, which cause a switch-off delay. On the basis a remark example represented in the designs the invention is more near described. Show: Fig.1 from the GB-PS well-known overload protection circuit for a loudspeaker arrangement, and Fig.2 an improved overload protection circuit for a loudspeaker arrangement in accordance with the invention. In Fig.1 is because of the clamps --1, 2-- the audio frequency tension on. The loudspeaker which can be protected --La-- is direct with a connection to the clamp --2-- and with the other connection via a normally-closed contact --r-- a relay --S-- to the clamp --1-- attached. The relay --S-- is likewise because of the gorges --1 and 2--, whereby itself in the feeder line to the clamp --1-- a breakdown diode --ZD-- and an adjustable pre-resistor --EGG-- find. Parallel to the relay a condenser lies --C--. In the Verblndungsleitung of the make contact --A-- the relay --S-- to the loudspeaker --La-- a pre-resistor lies --R2--. The well-known circuit after Fig.1 works as follows: With reaching the breakdown voltage of the breakdown diode --ZD-- becomes leading this as electric rectifiers and loads the condenser --C-- over the adjustable pre-resistor --EGG-- up. If the specific bias-reducing potential of the relay is reached, then this tightens. The loudspeaker receives now over the pre-resistor --R2-- the audio frequency tension supplied. The resistance --R2-- it is in such a way bestlmrat that an overloading of the loudspeaker with security cannot take place. It can be intended also in place of inserting the pre-resistor complete switching off of the loudspeaker. By the correct vote of --G 1 and C-- Anzug-und AbfaUverzögerung is reached, so that a flutter of the relay in the Schaitbereich is prevented. The supplied energy at the connections sinks --1 and 2-- off, the relay drops back into the state of rest and initial condition automatically. The loudspeaker preserves now again directly in such a way the K] Arùrùen --I and 2-- on, the electronic transistor-steered execution of a automatic and selbstheüenden protection after the invention, pointed out in Fig.2, scolded more accurately and is universally adjustable on any Schaitbereiche and/or load factors of the loudspeaker. As high and wfinschenswerte a switch-off delay of the relay as possible prevents a too early shifting back to the initial condition. The audio frequency tension is appropriate for the clamps --1 and 2-- on, in the same way also the loudspeaker lies --La-- over the normally-closed contact of the relay switch --$2-- directly at the clamps --1 and 2--. In the feeder line of the make contact --A-- the switch --$2-- the pre-resistor lies --R2--, The relay --æ--, a condenser --C2-- is parallel switched, lies as load in the emitter circle of a transistor --Tr--. In the heading for circle of this transistor the series connection of the defining resistor lies --G 1-- and the condenser --C1-- (--G 1 and c1-- are separable by the normally-closed contact --r-- the relay switch --$1--), and parallel to it a Spannungsteüer from adjustable resistances --R4, R3-- for adjustment the operating point and a breakdown diode --AD--, whereby the latters over the make contact --A-- the relay switch --SI-- to the condenser --CI-- are turn onable. The circuit after Fig. 2 works as follows: Over a diode --DL-- the lying close audio frequency tension is gieiehgerichtet; over the resistance --EGG-- becomes thereby in a state of rest the relay --S-- the condenser --C-- with DC voltage loaded. Reaches produced DC voltage over the Spannungsteüer --R4, R3-- on --R4-- the Durchbruehspannung of the breakdown diode --ZD-o, then becomes the breakdown diode leading. Thus becomes --R4-- shunt and the transistor scolded through. The relay --S-- tightens and with it go the relay switches --S1 and $2-- in working position (A). No. 34908T the condenser --el-- with the potential to the operating voltage of the Schalttransistors is now because of the basis and holds the Schalttransistor as a function of by the condenser --C1-o and the resistance =-R3-- given time constants in the connected through condition. Furthermore serves except the condenser --C2= now the condenser - =Cl-- again as Ladekonden= s sator, if pulsed voltages at the breakdown diode cross the breakdown voltage again. The condenser --C2-- serves additionally the switch-off delay, if tension breaks arise, which lie underneath the breakdown voltage of the breakdown diode. In the working position of the relay the loudspeaker becomes ==La== over a pre-resistor --R2=o to the audio frequency tension put, u.zw for the length of time, in which the transistor in the durchgez0 switched themselves condition finds. The energy at the clamps reduces itself --1 and 2--, then the breakdown diode closes =-ZD-- and at expiration of the discharge process of --Cl-- the Schalttransistor closes. The relay drops back into the state of rest. The loudspeaker is because of the clamps - to =1 and 2 now again directly-- on. In the Fig.1 and 2 elektromagnetisehe relays are intended as relays. In principle are also zs electronic relays and/or electronic relay switches --S1 and S2-o (transistors, thyristors etc.) with according to modified heading for circles conceivably.