DE1218001B - Circuit arrangement for generating two mutually offset pulses - Google Patents

Description

Circuit arrangement for generating two mutually offset in time Pulses The invention relates to a circuit arrangement for generating two times mutually offset pulses by a single trigger pulse, the pulse widths are determined by recharging capacitors.

Two monostable multivibrators are usually used for this purpose connected in series. The first monostable multivibrator is triggered by the input pulse triggered and gives after a predetermined time depending on its recharging capacitor an output pulse from; this will trigger the second multivibrator at the same time and in turn gives a second depending on its recharging capacitor Output pulse. But you must be very careful that the two Actually tilt the multivibrators in the intended order. It always exists the risk that the second multivibrator (e.g. as a result of specimen variations in the transistors used) accidentally flips with the first multivibrator. Are the time constants of both multivibrators are the same, so in this case both give at the same time their output pulse from; is the time constant of the second multivibrator smaller than that of the first, then gives when both multivibrators are tilted at the same time the second emits its output pulse before the first multivibrator. This allows but significant errors occur in the downstream stages. To avoid this, the two multivibrators connected in series are connected via diodes (or corresponding Switching elements) mutually positively controlled.

The invention relates to a particularly simple circuit arrangement for generating two mutually offset pulses and is marked by a monostable multivibrator known per se, consisting of a first Transistor and a second transistor, whose bases each have a forced control diode to the collector-emitter path of a third transistor, which is conductive in the quiescent state are connected, the base voltage divider with the collector circuit of the first transistor is connected so that a first pulse and through the monostable multivibrator a second, temporally offset from this first pulse by the is supplied as a second monostable multivibrator operating transistors.

The invention is shown below on the basis of an exemplary embodiment explained in more detail and shown in the block diagram.

In the idle state, the transistor T3 is conductive. The base stream of the two Transistors Ti and T2 are controlled via the forced control diodes Dl and D2 and the collector-emitter path of the transistor T., derived so that the two transistors T1 and T2 when conducting State of the transistor T3 are safely blocked. Is now through a positive Input pulse the transistor T1 is conductive, because of the in the collector circuit of the transistor T1 lying base voltage divider of the transistor T "this blocked. The charge reversal capacitor Cl, whose capacity for the duration of the first output pulse is responsible, can now discharge, through the resistors R1 and R2. The transistor T2 remains blocked during this time. Is the recharge capacitor Cl discharged, the transistor T2 is conductive and the transistor T1 is blocked.

The process described so far is equivalent to tilting one back monostable multivibrator, which would consist of the transistors Ti and T2.

As soon as the transistor T2 is conductive, the charge-reversal capacitor discharges C2. After the discharge time has elapsed, the transistor T ″ becomes conductive again, and the basic state is restored, d. e., the second monostable multivibrator from the transistors T2 and T3 tilt back and thus deliver the second in terms of time compared to the first offset output pulse.

Of course, instead of those assumed in the exemplary embodiment npn transistors for positive input pulses also pnp transistors for negative ones Input pulses are used.

It has proven to be useful to use a voltage divider resistor at the base voltage divider of the transistor T1, which is directly controlled by the trigger pulse by a zener diode D3. This ensures that when the transistor is blocked Ti the relatively strong fluctuations due to specimen scatter Residual currents of the transistor T3 and the forced control diode D1 not to the base of the transistor T1 can arrive, so that it remains blocked with certainty.

The two diodes D4 and D5 in the charging and discharging circuit of the recharging capacitor C2 keep the base of transistor T $ from positive pulses when charging of the charge-reversal capacitor C2 free, so that the transistor T3 when discharged with certainty remains locked.

Claims (3)

Claims: 1. Circuit arrangement for generating two temporally offset pulses by a single trigger pulse, the pulse widths being determined by recharging capacitors, characterized by a monostable multivibrator known per se, consisting of a first transistor (T1) and a second transistor (T2), whose bases are connected in a conductive in the idle state the third transistor (T3) via a respective positive control diode (D "D.) to the collector-emitter circuit whose base voltage divider is connected to the collector circuit of the first transistor (T1), so that the monostable by the Multivibrator (T1, T2) a first pulse and a second pulse that is offset in time from this first pulse is supplied by the transistors (T2, T3) operating as a second monostable multivibrator. 2. Circuit arrangement according to claim 1, characterized characterized in that a base voltage divider resistance of the trigger pulse directly controlled transistor (T1) is a Zener diode (D3). 3. Circuit arrangement according to Claim 1 and 2, characterized in that between the charging and discharging circuit of the second charge-reversal capacitor (C2) and the third transistor, which is conductive in the idle state (T3) two diodes (D4, D5) are connected.