SU815653A1 - Pulse generator - Google Patents

Description

The invention relates to electrical measuring equipment and can be used to test the operability of electronic logic circuits. Pulse logic generators are known for testing the operability of electronic logic circuits. Logical pulse generators provide short circuit signals to the nodes of the circuit, switching these nodes to logical states that are inverse to the existing ones. The known devices comprise a setpoint pulse generator, a control circuit and two current amplifiers ij. However, such generators do not provide indications of generator states. The closest technical solution to the present invention is a logical pulse generator containing a single pulse generator, a control circuit, the first input of which is connected to the output of a single pulse generator, two current amplifiers, whose inputs are connected to the outputs of the control circuit, an overvoltage protection circuit which is connected to the output terminal of a logical pulse generator and two outputs to the outputs of current amplifiers, and a state analysis circuit, the input of which is connected to the third output of the PDUs overvoltage hseNIN and output - to a second input of control circuit 2. The disadvantage of this pulse generator is the low reliability and consistency of the control of the logic digital elements. The purpose of the invention is to increase the reliability and consistency of control of digital elements. This goal is achieved by the fact that a pulse generator containing gamma. single pulse impulse, control device, the first input of which is connected to the output of a single pulse generator, two current amplifiers, whose inputs are connected to the outputs of the control device, overvoltage protection device, the input of which is connected to the output bus of the pulse generator, and output to the outputs of amplifiers current, and the state analysis device, the input of which is connected to the output of the protection device and the output - to the second input of the control device, introduced a second state analysis device p the decoder state indicator, two one-shot, two 3 AND-NOT elements and a second single pulse generator, while the second state analysis device is connected to the output of the protection device, the output of the first state analysis device is connected to the first input of the first AND-3 element and the output of the second state analysis device to the first input of the second element 3 NAND. The outputs of the first and second element 3 AND-NOT are connected, respectively, to the inputs of the first and second single vibrator, the output of the first single viral to the second input of the second element 3 AND-NOT, the output of the second single vibrator to the second input of the first element 3 AND-NOT. The outputs of the elements 3 I-NOT and one-shot are connected to the inputs of the state decoder, to the output of which the status indicator is connected. The input of the second generator of single pulses is connected to the output of the first generator of single pulses, the output of the second generator of single pulses - to the third inputs of the elements 3 AND-NOT.

FIG. Figure 1 shows a structural electrical circuit of a logic pulse generator; in fig. 2 timing diagram of the generator when generating a positive pulse.

The pulse generator contains a generator of 1 single pulses, consisting of switch 2 and one-shot 3, control device 4, consisting of firing element 5, NOT 6 and 2 AND-7 elements 7 and 8, Current amplifiers 9 and 10, respectively positive and negative impulses overvoltage protection device 11, pulse generator output bus 12, state analysis device 13 and 14, two elements 3 YO-15 and 16, two single-oscillators 17 and 18, decoder 19 states, indicator 20 First, the second generator 21 single pulses. The switch 2 is connected to the input of the single-vibrator 3, the output of the one-vibrator the 3rd by the first inputs of the elements 2 TH-7 and 8, the outputs of the current amplifiers 9 and 10 are connected, respectively, with the outputs of the elements 2 AND-NOT 7 and 8, the outputs of the amplifiers 9 and 10 currents - with the second output of the protection device 11, the input of the protection device 11 is connected to the LED terminal 12, the second output of the protection device 11 is connected to the inputs of the state analysis devices 13 and 14, the outputs of the devices 13 and 14 are connected, respectively, to the first inputs of the elements 3 AND-NOT 15 and 16, the output of the element 3 AND-NOT 15 Connected to the input of the one-shot 17 and with the first entrance

19 states decoder, output of element 3 AND-NOT 16 - with input of one-shot 18 and with fourth input of decoder 19 states, output of one-shot 17 - with second input of decoder 19 and with second input of element 3 AND-NOT 16, output of one vibrator 18 is connected with the third input of the decoder 19 and with the second input of the element 3 AND-NOT 15, the output of the decoder 19 is connected to the indicator 20 states, the output of the device 14 state analysis - with the input of the delay element 5, the output of the element 5 - with the second input of the element 2 I- NOT 7 and with the input element NO 6, the output element NO 6 is connected to the second m input element 1ta 2 AND-NOT 8, the output of the one-shot third input of the second generator 21 single pulses, the output of the second generator 21 single pulses connected to the third inputs of the elements 3 AND-NOT 15 and 16.

FIG. 2 shows the timing diagram — 22 output signals of the one-shot 3; -23 output signals of the second generator 21 single pulses / —24 voltage changes on the output bus 12, —25 output signals of the state analyzer 14, —26 output signal of the state analyzer 13 , - 27 output signal of the element 28 of the output signal of the one-shot 17, 29 output signal of the element 2 AND-NOT 16.

Pulse generator operates as follows.

In the initial state, the output bus 12 is not connected to the controlled point.

The voltage on the output bus 12 is higher than the logic level O, but lower than the logic level 1.

At the outputs of state analysis devices 13, 14, the levels of logic O, at the second input of element 2 AND-NOT 7, the level of logical O, at the second input of element 2 AND-NOT 8, the level of logical 1, switch 2 is in the open state at the output one-shot 3 and at the first inputs of elements 2 YO-NOT 7 and 8 is a logic level O, at the outputs of elements 2 I-NE 7, 8. and at the inputs of amplifiers - the level is logical 1, the output impedances of the amplifiers 9 10 current in this state are very large . At the output of the generator 21 single pulses and at the third inputs of elements 3 AND-NOT 15 and 16 - the level of logic 1, at the outputs of elements 15, 16 - levels of logic 1, at the outputs of one-shot 17 and 18 levels of logic 1, at all inputs of the decoder 19 - levels of logic 1, the status indicator 20 indicates the state — logical uncertainty.

When the output terminal 12 is connected to the controlled point, the output levels of the state analysis devices 13 and 14 depend on the voltage level at the controlled point. When the voltage at the contacted point is above the logic level 1, the outputs of the circuits 13, 14, respectively, are levels 1 and 0, the output of element 15 and the first input of the decoder 19 is the logic level O, the status indicator 20 indicates the state - logical 1 When the voltage at the controlled point is below the logic level O, the outputs of the circuits 13 and 14, respectively, are the levels O and 1, the output of the element 16 and the fourth input of the decoder 19 is the logic level O, the status indicator 20 indicates the state logical O. If the output terminal 12 is not electrically contact with the test point or if the voltage at the test point is above the logic level O but below the logic level 1, the outputs of the circuits 13, 14 are the logic level O and the status indicator 20 indicates as in the initial state of the generator, state - logical uncertainty.

When the output bus 12 is connected to a controlled point, where the voltage is below the logic level O, and when the button 2 of the switch is pressed, the pulse generator generates a single positive pulse and the 20 status indicator indicates the state - a single positive pulse. The generation of a positive pulse is illustrated in the time diagrams of FIG. 2. Pressing the switch 2 button on the time moment TQ starts the one-shot 3 and the generator 21 single pulses. The single-vibration 3 produces a positive pulse with duration TI 1-22, the generator 21 single pulses produces a negative pulse with duration TI 2-23. A positive impulse - 22 goes to the first inputs of elements 2 AND-NOT 7 and 8. The passage of a pulse either through element 7 or through element 8 depends on the voltage on the output terminal 12. Since the output terminal 12 is connected to a controlled point where the voltage below the logic level O - 24, the output of the state analyzer 14 is the logical 1 level, the second input of the element 7 is the logic 1 level, and the second input of the 8 element is the logic O level.

The pulse passes through the element 7, is amplified by the current amplifier 9, and, acting on the output terminal 12, switches the logic state at the checked point of the logic circuit,

At the output of circuit 14, time level T 1-25 is set to a logic level O, but since the delay in delay element 5 is greater than the duration of pulse TI 1, the logic state at the inputs of elements 7 and 8 during pulse TI 1 ke changes. At the output of element 13, at the time moment T1 - 26, the level of logic 1 is set, during TI223 the negative pulse of the generator

o 21 single pulses prohibits the switching of elements 15 and 16. When the negative pulse ends at the time moment T2 - 23, all the inputs of element 3 are NOT 15 and the logic level 1 and element 15 switches to 27, starting the one-shot: 7.

A single vibrator 17 produces a negative pulse TIZ-28, which

0 is fed to the second input of the decoder 19 and to the input of the element 16. From the decoder 19, the pulse arrives at the indicator of 20 states, which — about 100 ms — during the TIZ pulse, indicates the state — logical 1. At the time moment of the TOR at the output terminal 12 sets the level of the logical O - 24, the output of the element 14 sets the level of logical 1 - 25, which

0 enters the input element 16.

The second input of the element 16 from the output of the one-shot 17 receives a negative pulse MTH - 28, which switches the element 16 at the time moment T4 - 29. From the output of the element 16 the level is logical. O is fed to the input of the decoder 19 and the status indicator 20 after the pulse of the SIZ - 28 indicates the state 0 logical O.

When the output bus 12 is connected to a controlled point, where the voltage is above the logic level O, and when the switch 2 button is pressed, the generator generates a single negative pulse and the status indicator 20 indicates the state — a single negative pulse. Since the voltage on the output bus 12 is higher than the logical level

O O, at the output of circuit 14 and at the second input of element 7, logical O, at the input of element 8, logical 1.

Pulse ТИ1 - 22 passes through the element 8, is amplified by the amplifier

5 10 and, arriving at the output bus 12, switches the logic state at the check point of the logic circuit. The output of the device 14 is set to the logical level 1 and, after a negative pulse of the generator 21 of a single pulse of duration TI2 - 23 at the second input of the element 16, the element 16 switches, starting a one-shot 18, from the output of which a negative name 5

a pulse with a duration of about 100 m goes to the third input of the decoder 19 and the indicator 20 states during a pulse indicates the state — logical O.

When the output bus 12 is connected to the power bus or to the common bus, the status indicator 20 indicates, respectively, the state — logical 1 or logical O. To distinguish the logic circuits from the power circuits or to detect a short circuit of the logic circuit with the power bus or with the common bus, on the circuit under study, it is necessary to apply a pulse from a pulse generator. The generator is capable of generating switching pulses of duration TI1-24 if the output bus 12 is connected to a logic circuit, i.e. If the output bus 12 is connected to the power bus or to the common bus, the generator is not able to generate pulses of duration TI1-24, but the generation of powerful pulses causes short-term impulses that switch high-speed state analysis devices 13 and 14 In the proposed pulse generator, the generator of 21 single pulses produces a negative pulse - 23, which during TI2 prohibits switching of elements 15 and 16. Thus, with output pulses A pulse generator with a duration of less than TH2, elements 15 or 16 are not switched, one-shot 17 and 18 are not triggered, and pulses are not indicated by an indicator of states 20, as devices for analyzing states 13, 14 also circuits are used, in which the switching time is only slightly less than the duration of the generated TI1 pulse. However, in this case, the functionality of the proposed device is reduced, as when using high-speed state analysis devices. 13 and 14, this generator is used as a high-speed logical indicator.

The use of a pulse generator makes it possible to increase the consistency of the logic circuits, since the output logical static state and the output pulses of the generator are indicated. The speed and reliability of the control increases, as it is possible to quickly verify that the generator is in good condition, that the generator is correctly connected to the tested point and to observe the response of the tested circuit at the point

generating stimulating pulses. With the help of a generator, one can quite reliably distinguish the logic signal circuits from the power supply circuits and detect short circuits between the logic signal circuits and the power supply circuits.

Claims (2)

1. Electronics, 1975, No. 19, p. 37-45. 2. Devices and control systems, 1977, No. 10, p. 50, 51. 1 TO G, tg Tjr Fmg