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Combination of 555 timer and standard opamp minimizes cost of adding triggered sweep to oscilloscope not having this feature. Timer is triggered by applying vertical-amplifier signal through opamp, initiating charging of sweep capacitor C. When capacitor voltage reaches control voltage of timer (0.33 VCC), flip-flop in timer resets and capacitor discharges to form retrace of sweep.- Signetics Analog Data Manual, Signetics, Sunnyvale, CA, 1977, p 726.

Developed for use with general-purpose CR0 in troubleshooting digital circuits, to provide one horizontal sweep of cathoderay beam each time circuit is triggered by input signal pulse. Noninverting input of 741 opamp is connected to vertical amplifier of CRO,and inverting input is used to control trigger level. When input signal rises above trigger level, output of opamp swings to -V and makes output of 555 timer go high, allowing output capacitor to charge at constant cuirent through transistor in series with resistor. Resultis nearly perfect ramp voltage. All diodes are 1N914. an is any PNP switching transiston-W. J. Prudhomme, Trigger Your Oscilloscope, Kilobaud, Aug. 1977, p 34-38.

LINEAR SAWTOOTH GENERATOR

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NE555 2N3906     The 2N3906 transistor is used as a constant-current source, to assure that the 555-based sawLooth generator generates a linear ramp waveform.

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Two 2N3904 transistors and a 555 form a triggered sawtooth generator. A sawtooth or other rising voltage input provides a pulse output when the trigger point is reached.

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OP_AMP_SAWTOOTH_GENERATOR

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The sawtooth generator circuit shown is reset at the end of each cycle. The result is a constant peak-to-peak output throughout the circuit's frequency range.The constant-current generator circuit, the voltage-follower circuit, and the comparator circuit produce the waveform. A 555 timer IC (U2) is configured as a one-shot multivibrator that's triggered by the comparator's negative output pulse.