Ttl/Cmos Level Generator; Fm Signal Generator - VOLTCRAFT 8202 Bedienungsanleitung

7.3 TTL/CMOS level generator

The TTL or CMOS output is intended for certain logical circuits. The amplitude of the TTL level is set. You
can adjust the CMOS level continuously in a range from approx. 5 to 15 Volt. You can adjust the fre-
quency and symmetry of both TTL and CMOS levels. Adjusting the DC offset is not possible. Both levels
are above zero.
The TTL level is applied when the knob „TTL/CMOS" (12) is pressed. The variable CMOS level is applied
when the knob „TTL/CMOS" is pulled.
Connect a screened 50 Ohm BNC measuring cable to the TTL/CMOS output (6). Connect the red clamp
(signal) with the pulse input of the logical circuit and the black clamp (ground) with the ground of the logi-
cal circuits.
The TTL/CMOS output can be used as a real pulse generator for TTL or CMOS circuits.
With this output, you can „drive" all TTL-CMOS circuits (up to 15 V).
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.

7.4 FM signal generator

Frequency modulation (FM) is the change of the output frequency in dependence on the progression of
a second supplied control frequency.
In order to use the frequency generator as a frequency-modulated signal generator, proceed as follows:
a) Make the basic settings for the function generator as described in 7.1. Set the carrier frequency with
the knob "FREQUENCY" and the amplitude with the knob "AMPL".
b) Apply a true alternate voltage signal (modulation voltage without direct current ratio) on the VCF input
(5) via a BNC measuring cable (HF cable) .
c) Change the applied modulation voltage (max. 10 Vpp) until the desired frequency deviation is reached.
An approximate display of the correlation between the frequency modulation and the alternate voltage
(modulation voltage) applied on the VCF input is described as follows:
A change of the alternate voltage on the VCF input (VCF IN) by 0.1 V results in a frequency change of
1% of the highest possible frequency setting (MAX range of the knob "FREQUENCY") of the respective-
ly set frequency range.
E.g. if the switch „100 k" in the field "FREQUENCY RANGE (Hz)" is pressed, the maximum achievable
frequency in this range is approx. 200 kHz. A change by 0.1 V corresponds to a frequency change by 2
kHz. The following table shows the correlation between the set range, the max. achieved frequency and
the frequency change per 0.1 V voltage change on the VCF input.
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