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HEWLETT-PACKARD
JOURNAL
TECHNICAL INFORMATION FROM THE -ftp- LABORATORIES Vol. 7 No. 11 -12
^B^^^^^^^^^^H
iLISHED BY THE HEWLETT-PACKARD COMPANY, 275 PAGE MILL ROAD, PALO ALTO, CALIFORNIA JULY-AUGUST, 1956
A 0-1.1 MC Frequency Counter
with Time Interval Markers
ANEW -hp- frequency counter has been cies, measure the period or 10-period average
designed which incorporates a number of lower frequencies, and act as a secondary
of new features and which also includes the frequency standard by making available ex
previously-developed features that have al ternally an accurately-controlled 100 kc fre
ways given -hp- counters their leading posi quency.
tion in the field. The new counter measures The basic circuit arrangement of the new
frequencies from 0 to 1.1 megacycles and counter is shown in Fig. 3. The frequency to
time intervals from 3 mi be measured is passed through a gate circuit
croseconds to 27.8 hours. which is opened by a precision time-base cir
These ranges suit the in cuit for an accurately-controlled interval
strument to much of the frequency-measur such as 1 second. A panel switch permits the
ing work that goes on in a typical electronics operator to select in decade steps any of five
laboratory as well as to almost any of the gate times from 1 millisecond to 10 seconds.
mechanical applications where a counter is The cycles of the frequency to be measured
useful such as in measuring rpm, velocity, that pass through the gate are then applied
flow rates, etc. Besides measuring frequency to a series of six decade counting units which
and time intervals, the instrument will also indicate in illuminated numerals the num
count events, i.e., totalize, for as long as de ber of cycles that have occurred while the
sired, form the ratio of two external frequen gate was open. The measured frequency can
Fig. 2. Oscillogram showing how time in
terval markers (bright dots) can be used
to insure measurement of pulse width on
noisy signals.
Fig. 1. (left.) New -hp- Model 523B Counter has
been designed with such features as time interval
measurement markers, circuit check lamps, and
the -hp- illuminated, automatically-positioned dec
imal point which prevents measurement ambig
uities. (Chart on back page shows how new 523B
fits into -hp- counter line.)
P R I N T E D I N U . S . A . C O P Y R I G H T 1 9 5 6 H E W L E T T - P A C K A R D C O .