DE680758C - Receiver with mains transformer and rectifier for optional connection to networks of different types of current - Google Patents

Description

Receiver with mains transformer and rectifier for optional connection to networks of different types of current It is known to have an all-current receiver with a Mains transformer to be provided so that such a receiver in AC operation is not inferior to an AC mains receiver in its properties and thus a sufficiently high anode voltage, especially with an alternating voltage of 10 volts is available.

Since the transformer is not required for direct current operation, it has already been used as a choke for direct current operation. For the sieving of the anode current in AC operation, an ohmic resistor was then provided. However, sieving with an ohmic resistance is not sufficient in all cases and is also energy consuming. These disadvantages become when the invention is used avoided.

According to the invention, a receiver with a power transformer and rectifier is provided for optional connection to networks of different types of current and, if necessary, different Voltages at which the mains transformer acts as a choke for direct current operation Screening of the rectified current is used, constructed in such a way that the field coil of the loudspeaker only with direct current operation, if necessary via a series resistor, parallel to the mains, but serves as a choke in AC operation.

Using the field coil as a choke is on. already known. When applied to all-current receivers, it would be obvious to use the field coil for both To use types of current as a choke. In contrast to the invention, this would be unfavorable, because the field coil has a relatively low anode current have a high number of turns. must and therefore there is a high voltage drop across it, which is very undesirable in DC operation.

In the invention, these disadvantages are not present, because with AC operation the transformer voltage can be increased to compensate for the voltage loss and on the other hand one can dimension the transformer so that it is in use as a choke causes only a small DC voltage drop. It is Z. B. possible to use only a part of the turns of the transformer for direct current operation or to connect winding parts in parallel.

Further improvements according to the invention to an all-current receiver are to be explained below with reference to Fig. 2. In For the sake of simplicity, Fig. I shows the circuit of the power supply unit for the case that the receiver for two types of current, but only for a single voltage is usable. The mains transformer, which is designed in particular as an autotransformer is denoted by T. The rectifier tube is used for AC operation Gl for rectification and the field coil F of the loudspeaker as a choke. The switches are switched to AC operation in Fig. i; what by the designation W is indicated. In the case of direct current operation G, the rectifier tube is short-circuited and the field coil F; if necessary via a series resistor V, directly laid the direct current network. The transformer T ,. then serves as a throttle.

With different mains voltages there are several for direct current operation Series resistors (or a series resistor with taps) are necessary, however not with alternating current because of the switchover at the transformer.

It would therefore be obvious to switch off the series resistors in AC operation with a current type switch. According to the further invention, however , these ballast resistors are built into the replacement base of the rectifier tube, which is used in place of the rectifier tube in the case of direct current operation. Such replacement base without built-in ballast resistors. Has already been used so that the buyer of an all-current receiver can save the rectifier tube; if he only needs the receiver for DC operation.

In Fig. 2 below is the replacement base with the eight around the circumference See contacts. The cables and parts in this base and also in that The rest of the figures are marked with W if: they are operated with alternating current are present or used, while the letter G stands for direct current operation is applicable.

The invention is further perfected by the switching the series resistances for the field coil at the various DC voltages through excess contacts on the ferrous hydrogen resistor (E in Fig. z) of the heating circuit happens. These contacts are useful for voltage switching in AC operation on the transformer; so that no special voltage switch is necessary.

The redundant contacts of the ferric hydrogen resistance were previously to achieve a constant voltage (screen grid voltage, oscillator voltage) used despite different line voltages. - For this purpose are the purchasable Ferrous hydrogen resistances; in which there is also a uranium dioxide resistance (U in Fig. 2) is built into the base to eliminate an overcurrent when switching on Provide short-circuit connections of the surplus contacts. These connections are naturally with the individual ferric hydrogen resistances determined for the various tension gauges different.

In the circuit according to the invention of an all-current receiver these contacts are not required for the primary circuit to achieve a constant voltage, since, according to a further object of the invention, the constant voltage in direct current operation is taken from the circuit of the field coil, since yes, with all DC voltages the same current must flow through the field coil. With AC operation, this can Voltage taken from a voltage divider connected in parallel to the anode voltage because with AC operation, despite different mains voltages, there are the switchable mains transformer has a constant anode voltage.

The above-mentioned contacts in the base of the ferric hydrogen resistor are shown in Fig. 2, above, and also those for the various voltages (in this example i io volts, i 50 volts and 22o volts) existing connections in the base.

With an all-current receiver; which switched according to the example in Fig is, the switch to different types of current is done firstly by exchange the rectifier tube against a replacement socket and, secondly, by actuating one Changeover switch that controls the switching contacts shown near the mains transformer and actuates the contacts on the field coil. Switching to different voltages only happens by changing the ferric hydrogen resistance.

The circuit according to Fig.2 can be used for the various voltages and types of currents easily traced if one observes; that all in AC mode The cables and individual parts used are designated with ZV and those for direct current operation lines used with G.

In this example, the rectifier tube filament is in series connected to the heating filaments of the receiver tubes, but it is known per se Way also possible to have a heating coil on the mains transformer for the rectifier tube to be provided.

The main feature of the invention related to the power transformer and the field coil can also be used when at DC operation the rectifier tube not removed and the ferric hydrogen resistance not is replaced, but when the receiver by switching the iron hydrogen resistance or the inclusion of ordinary resistors in the heating circuit of the various Line voltages is adjusted. Then you can switch a type of current in a manner known per se provide and a voltage switch that is used for both types of current at the same time.

Claims (1)

PATRNT CLAIM: r. Receiver with mains transformer and rectifier for optional connection to networks of different types of current and, if necessary, different Voltages at which the mains transformer acts as a choke for direct current operation Screening of the rectified current is used, characterized in that the field coil of the loudspeaker only in DC operation, if necessary via a series resistor, parallel to the grid, but with AC operation. serves as a throttle. a. Receiver according to Claim r, characterized in that, in the case of direct current operation ballast resistors used for the field coil in the replacement base for the rectifier tube are arranged. 3. Receiver according to claim r, characterized in that the switching the series resistances of the field coil for various DC voltages due to excess Contacts at the iron hydrogen resistance of the heating circuit happens and that * this In AC operation, contacts are used to switch the voltage on the transformer. q .. Receiver according to claim i, characterized in that one at different Mains voltages constant voltage (screen grid voltage, oscillator voltage) tapped from the circuit of the field coil of the loudspeaker in DC operation will.