DE1051039B - Electronic switching stage - Google Patents

Description

Electronic switching stage In general, counting arrangements are known certain events by adding an electrical impulse from each event to be counted is derived, which is used to trigger the counting arrangement. Such counting arrangements work partly on the electromechanical principle, such that a mechanical Counter is operated by an electronic control circuit. Other arrangements work purely electronically when using electron tubes or gas discharge tubes. In many cases there will be an advantageous combination of these two options applied by considering the higher resolution of the electronic counting devices exploited and then after a corresponding reduction by a mechanical counter the counting capacity with relatively little effort by a few powers of ten expanded.

Unless such counting arrangements are the simplest of designs belong, one demands from them, among other things, the possibility of certain step numbers to be able to preselect, after which the arrangement stops automatically and thereby usually triggers another process, e.g. Usually switches a timer. Included with regard to the measurement accuracy, it is required that the switching time of the switch-off process is smaller than the resolution time, so that it does not turn on during shutdown or several counting steps can be carried out.

This requirement can be met without any difficulties in principle as long as it is a purely electroaic or purely electromechanical counting arrangement acts.

In the case of the purely electronic counting arrangement, an electronic Input gate circuit controlled from a suitable point of the counting arrangement, by a control pulse for the first time at this point as a result of the nth, preselected pulse takes effect.

In the purely electromechanical counting arrangement, as a result of the 1st, preselected counting step by the counter a contact is switched that the electronic Star circuit locked.

In the known mixed electronic-electromechanical counting arrangements. So far, a preselection control from the mechanical counter has mostly been dispensed with, because with direct control by a counter contact the switching time is due to the moving mechanical masses cannot be made smaller than a few milliseconds and this is disproportionate to the resolution time, which is usually a few orders of magnitude smaller stands.

The invention described below relates to an electronic one Switching stage through which z. B. with mixed electronic-electromechanical counting arrangements interference-free preselection control through indirect control from the mechanical counter is made possible, in which the switch-off time in the order of magnitude of the resolution time of the electronic part of the counting arrangement.

The disadvantages of the known arrangements are avoided by that according to the invention a flip-flop during operation between the arrival two pulse pulses is switched from monostable to bistable function and when tilting as a result of the second key pulse at a pulse-free in the monostable state Terminal a control pulse occurs while at the same time by remaining the circuit in the second stable position, a further control process can be triggered and the forwarding of subsequent pulse pulses via the normal pulse output is prevented.

On the basis of the two drawings, an exemplary embodiment is shown the invention shown and explained in more detail.

The basic circuit of this switching stage is shown in Fig. 1.

The series connection of the resistors is parallel to the switch Sch R 6 and R 8. With the voltage divider R2-R3-R5 the grid of tube Rö 1 becomes one Voltage supplied so that the voltage drop across the resistor R7 due to the through the tube Rö 1 current flowing is compensated. The tube works through it with a grid voltage of OV and is fully open. The voltage drop over the resistor R1 as a result of the current through the tube Rö 1 is used to Set the grid potential of tube Rö2 via the voltage divider R + R9 so that that their operating point is below the cut-off point and the tube Rö2 is blocked remain.

The circuit is therefore statically a modified form of the known Univibrators and also behaves dynamically like this. Leads in peace the tube Rö 1 Strom.

One that reaches the grid of tube Rö 1 via the coupling capacitor C3 negative key pulse controls and thus reduces the anode current. This got on point 8 result in a positive voltage jump, which occurs via the coupling capacitor C2 reaches the grid of tube Rö2 and controls it. As soon as the anode current begins, the negative voltage jump that occurs at point 6 is over the Capacitor C1 transferred to the grid of the Röl tube and amplifies the original one Triggered by the touch pulse. This process rocks up and down like an avalanche leads to overturning the circuit in the metastable state by the tube Rö2 opened and tube Rö1 is blocked. This metastable state lasts so long on until the capacitor C1 is discharged in such a way that the tube Rö 1 current again begins to pull and the circuit tilts back into the stable starting position. at In this monostable operation, there is no pulse voltage at point 3, since this Point is blocked via the switch Sch by a sufficiently large capacity C5.

Fig. 2 shows an equivalent circuit for the static conditions in the stable state for the current-carrying tube Rö 1. The resistors Ri, R 7 and R 8 are provided with a dash index in the equivalent circuit diagram in order to show the influence of the Voltage divider R4 and R 9 to be taken into account. Because of the condition U - 0V for the Live tube is at point 4 and 5 of the circuit with the same potential. Possibly this is practically achieved by the onset of the grid current by the dashed line drawn low resistance Rgk becomes effective. Then the switch is Sch in the diagonal branch of a bridge circuit, formed from the resistors R5, I? fr R7 'and R8', which are matched so that no current flows through the switch Sch. If this switch is opened in the steady state the circuit changes nothing to do with this state, d. i.e. no tilting process is triggered. It takes place but the switchover from the previously monostable to the bistable circuit. The level is only in the second stable position with the next touch pulse tilted so that tube Rö2 draws current.

The negatively directed voltage jump occurs during this tilting process Transferred at point 6 via C1 to point 5. According to the voltage divider ratio R5-R6 this jump is also effective at point 3 and can be accepted via C4.

When the gearshift is in the second stable position, it is no longer influenced by subsequent negative key pulses. The initial position is restored by closing the switch Sch.

Fig. 3 shows an advantageous application of this electronic Switching stage in connection with a mixed electronic-electromechanical Counting arrangement. An electronic gate circuit (Block 1) leaves in the switching state »Start« the impulses to be counted at the input to an electronic counter (Block 2) pass. Its output pulses control the electronic switching stage (Block 3), at whose pulse output the excitation coil of the mechanical counter (Block 4) is connected.

The excitation coil can be located directly in the circle of this switching stage, or the control takes place indirectly with the help of any connected switching tube, right (Fig. 4 and 5).

When operating with pulse preselection, a suitable counter is used by the counter Z-controlled switching device after reaching a certain adjustable number of steps (n- 1) the switch Sch is open. When the nth pulse arrives, the point is 3 a negative pulse is available for the first time as a result of the switching stage tilting, which is used to switch (close) the electronic gate via path b will. By tilting the switching stage into the second stable position, the mechanical counters from step 11. The fact that the switching step then remains in its second stable position, can be used to trigger further switching operations - e.g. B. Operation of a stopwatch - expand by placing a sufficiently slow relay A is connected directly or indirectly to the switching stage, which only responds when the tube Rö2 carries current continuously.

PATEXTANSPStlCI1E 1. Electronic counting device, characterized in that that a trigger stage during operation between the arrival of two probe pulses is switched from monostable to bistable function and when tilting as a result of the second key pulse at a terminal that is pulse-free in the monostable state Control pulse occurs while at the same time by remaining the circuit in the second stab; ilen position another control process (A) can be triggered and the Forwarding of subsequent key pulses via the normal pulse compensation prevented will.

Claims (1)

2. Arrangement according to claim 1, characterized in that in the diagonal branch A contact is switched over in a coordinated bridge circuit. 3. Arrangement according to claim 1 and 2, characterized in that this in connection with a mixed electronic-electromechanical counting arrangement allows interference-free preselection by direct or indirect Actuation of the contact (SC7l) from the mechanical counter after the pulse has passed (n 1) the bistable stand-by position is established, so that during passage of the preselected pulse (ii) by the first outgoing control pulse (3) electronic input gate circuit is blocked, so that the switch-off time in the order of magnitude of the resolution time of the electronic part of the counting arrangement lies.