Pulse" Generator - VOLTCRAFT 8202 Notice D'emploi

7.2 "Pulse" generator

The symmetry function „SYM" is used for application as pulse generator. With a standard signal like sine,
triangle or rectangle resp. TTL, the ratio between positive and negative half-wave is 1:1. By pulling the
adjuster knob "SYM" (14), you activate the function "Symmetry setting", meaning the ratio between posi-
tive and negative half-wave can be changed more than 10:1 (in both directions!).
The a sinus signal turns into a straight sine, a triangle signal into a ramp or or sawtooth function and a
rectangle or TTL signal into a so-called needle impulse.
The following illustration shows an example of how the basic curves can change their appearance.
The dashed line ----- corresponds to the zero line.
Pulse (from rectangle)
Ramp (from triangle)
Straight sine
TTL/CMOS pulse
Proceed as follows to change the symmetry of basic curves:
a) Set the function generator as described in „6.3 Basic setting" and connect the output (7) with an oscil-
loscope. Always use a 50 Ohm terminator to prevent signal distortions.
b) Select the desired basic curve shape by operating the respective switch in the field "FUNCTION".
Press the switch for rectangular signals to receive needle impulses, the switch for triangle signals to
receive ramps or sawteeth or the switch for sine signals to obtain a straight sine.
c) For extremely short rise times and long drop times (ratio up to more than 1:10), pull the knob "SYM"
and turn it to the left (max. "unsymmetrics" all the way to the left). For extremely long rise times and
very short drop times, turn the knob „SYM" to the right (max. „unsymmetrics" all the way to the right).
By changing the symmetry, you also change the frequency and therefore have to readjust it.
Never exceed the max. input parameters, neither on the VCF input nor on the fre-
quency counter input, and do not cause a short circuit on the generator outputs
"TTL/CMOS-OUT" and "OUTPUT". Otherwise you may damage or destroy the fre-
quency generator.
Danger of a mortal electric shock when exceeding the max. input parameters or
coming into contact with voltages in excess of 25 VAC or 35 VDC.
In order to better adjust the ratio on a ramp (triangle) or a straight sine, we recommend
using the switch for the triangle signal in the field "FUNCTION". Afterwards determine the
period length of the rise and drop times on the oscilloscope and set these to the desired
values with the generator (with the knob „SYM" and „FREQUENCY"). Then select the
desired signal form.
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