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Model 5328A
Operation
3-26
3-91.
When the OSC INT EXT switch is in the INT position, the 10 MHz oscillator output is
available at the INT/EXT rear panel connector, providing TTL levels.
When terminated in 50
ohms, the OSC INT EXT output is a square wave of approximately 1-volt amplitude.
3-93.
Trigger Lights
3-94.
A trigger light is provided for each (A and B) input channels to enable the user to know not
only if the channel is triggering, but also in which direction the trigger level must be adjusted to
cause triggering. The light is ON when input is above the trigger level; OFF when input is below
the trigger level; BLINKING when channel is triggering. The trigger lights are operative over the
full frequency range of dc to 100 MHz.
3-95.
The trigger lights can be used with a 10:1 oscilloscope probe to provide a logic probe type
function.
By adjusting the trigger level to one tenth (since using 10:1 divider probes) of the
threshold voltage for the logic family under investigation (e.g., .14 volts for TTL), the light
indicates the logic state of circuit points which are contacted with the probe. When the trigger
level light is ON, the circuit node is a high (i.e., above the threshold voltage). If the light is OFF,
the node is a logical low. If the light blinks, then pulses (up to 100 MHz rep rate) are present at the
node. The trigger lights can also detect the polarity of low rep rate pulses down to 5 nsec pulse
width. Positive pulses cause the light to blink on while negative pulses cause the light to blink off.
3-96.
Delay (Option 040)
3-97.
The delay mode is activated by the inner concentric knob on the LEVEL A control of the
Option 040 Universal Model (read LED indicates that delay is activated).
In the delay mode,
Channel A triggers and is then disabled from triggering again until the delay times out (disabled
state occurs within 1 us after triggering). Channel B is continously disabled until the delay times
out. After the delay, both A and B are enabled. The delay time may be measured by placing the
counter in T.1. A~B and the Universal Module in check (CHK). The delay mode of operation is
illustrated in Figure 3-19. The range of delay time is continuously variable from 20 ys to 20ms. For
time interval average measurements using delay, the minimum dead time (time between the stop
signal and the next start signal) is 1 usec and is illustrated in Figure 3-20. Delay may be used in the
following functions: FREQ A, PER A, PERAVGA,
T.1. A~B, T.1. AVGA—B, RATIO C/A, START
A, EVENTS C, A-B.
3-98.
Delay mode is extremely useful for ignoring signals which would otherwise trigger the
counter.
Applications include relay timing measurements
(use "delay'' to ignore contact
bounce), pulse timing between nonadjacent pulses, and frequency measurements on noisy
signals.
at y@<1 us |
|
INPUT
SIGNAL: | Mn
| AA
I Nap
|
|
|
ee
Le
DELAY
20 us >|
|
TO
20
ms
COUNTER
COUNTS:
Figure 3-19.
Delay Mode
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