DE1053567B - Circuit arrangement for generating timer pulses for very long times - Google Patents

Description

GERMAN

For various control and regulation tasks, time-determining pulse generators are required, which are included in the Usually to be represented by contactless elements. However, this is the case with very long switching times not easily possible because, for example, the period of an electronic trigger circuit only can be set up to the order of minutes.

The invention provides a circuit arrangement for generating timer pulses for very created long times, which allows the setting of several times greater switching times. The invention is characterized in that two astable multivibrators of different period duration and with duty cycles close to 0 or 1 connected in parallel with a common input and through to the outputs an AND gate are combined, which is an output signal when the short-term tilting positions coincide gives away.

To explain the invention in more detail, an embodiment is described below, which is shown in the drawing is shown schematically.

As FIG. 1 shows, two asymmetrical, astable trigger circuits I, II connected in parallel are combined at the outputs by an AND gate G. Flip-flops and gates are constructed in a manner known per se, so that a more detailed description of their circuit is not necessary. The start of the switching time is determined by a signal at the input terminals of the multivibrator circuits, for example by a switch S.

In Fig. 2, the output signal of the two flip-flops is shown as a function of time. The example of flip-flops is considered, which within a period initially one output a positive and then a negative output value. Of course, either of these could be Values also equal zero. You just have to make sure that the and gate for processing the Coincidence of the short-term output pulses is capable.

The flip-flop I has a period T ₁

and a duty cycle

«I.

«1+ bi

that according to the invention

close to 1 is chosen. This means that the time b _{1 is} negligibly small compared to the time% or the period duration T ₁ . Conversely, O ₁ could also be chosen to be small compared to b _l.

Analogous considerations also apply to the trigger circuit II, which has a different period T ₁₁ .

The coincidence of the short-term impulses (& j, & _n ) will always occur if there are several periods
for generating timer pulses
for very long times

Applicant:

Siemens-Scliuckertwerke
Aktienges ells ctiaf t,
Berlin and Erlangen,
Erlangen, Werner-von-Siemens-Str. 50

Dr.-Ing. Georg Sichling, Erlangen,
has been named as the inventor

the flip-flops I and II are ended at the same time. The condition for this is

Z ₁ -T ₁ = Z ₁₁ ■

where Z ₁ , Z _{11 denote} the number of periods. Of course, coincidence only occurs when Z ₁ and Z _{11 are} each different by an integer, the first coincidence accordingly for Z ₁ = Z ₁₁ -II. This results in the first coincidence

or

Zn 'T _n = (Z _a + I) - T ₁ T ₁

Z ₁₁ =

T ₁ JT ₁

Z ₁₁ indicates the number of periods of the flip-flop II at which coincidence occurs for the first time and the AND gate emits an output signal. This number of periods can be set as desired by appropriate selection of the difference T ₁₁ -T ₁ , the upper limit for the switching time in practice only being determined by the fact that the time b _z or ^ _{11 is} finite. For example, T _{1 can be kept} constant and T _{11 can be} changed. If the toggle switch T _{1 has} a period of, for example, one minute, switching times of 30 minutes and more can easily be achieved.
In the interest of saving space and power, transistors can be used to set up the flip-flops in a manner known per se. The toggle switch can work on the multivibrator principle or on another basis.

809 787/382

Claims (5)

The invention is particularly advantageously suitable for control devices of machine tools and of heat treatment processes, but is not restricted to these applications. Patent claims: 1. Circuit arrangement for generating timer pulses for very long times, thereby characterized in that two astable multivibrators of different periods and with duty cycles close to 0 or 1 are connected in parallel with a common input and combined at the outputs by an AND gate, the emits an output signal when the brief tipping positions coincide. 2. Arrangement according to claim 1, characterized in that the flip-flops consist of transistors are constructed. 3. Arrangement according to claim 1 or 2, characterized in that the switching time by change the period duration of a multivibrator is continuously adjustable. 4. Arrangement according to one of claims 1 to 3, characterized by the use in control devices of machine tools. 5. Arrangement according to one of claims 1 to 3, characterized by the use in control devices of heat treatment processes. 1 sheet of drawings © 809787/382 3.59