Text preview for : 1949-11.pdf part of Agilent 1949-11 Agilent journals 1949-11.pdf
Back to : 1949-11.pdf | Home
HEWLETT-PACKARD
JOURNAL
T E C H N I C A L I N F O R M A T I O N F R O M T H E - l i p - L A B O R A T O R I E S
VOL. 1 No. 3
SHED ALTO, NOVEMBER, HEWLETT-PACKARD COMPANY, 395 PAGE MILL ROAD, PALO ALTO, CALIFORNIA NOVEMBER, 1949
Design Notes on the Resistance-
Capacity Oscillator Circuit
Parti
VER a period of years the Hewlett- siderations involved in the design of the
ackard Company has been re resistance-capacity circuit.
quested to design and manufacture a Briefly, the resistance-capacity oscil
large number of special-purpose resis lator circuit consists of a two-stage am
tance-capacity oscillators having such plifier having both negative and positive
characteristics as compressed or expand ?feedback loops (Figure 2). The positive
ed scales, unusually wide frequency loop causes the circuit to oscillate and in
range, high power output, high and low cludes the resistance-capacity frequency-
frequencies, special controls, etc. The selective network which gives the circuit
following will describe some of the con- its name.
*1pHE "resonant" frequency of the
RC network is given by the well-
known expression f0=l/27rRC. The
negative feedback loop stabilizes the
operation of the circuit by minimiz
ing phase shift and confining oper
ation to the linear portion of the
characteristics of the tubes. One ele
ment of the negative feedback cir
cuit is a non-linear ballast resistance
which limits the amplitude of oscil
lation. The ballast element adjusts
its resistance either higher or lower
so as to compensate for any tendency
of the oscillations to vary in ampli
tude. If the non-linear element is
Figure Range Model 202B Lou' Frequency Oscillator Corering Frequency Range
from i to 50,000 cps. located in the cathode circuit, as in
PRI NTED IN U.S. A C O P Y R I G H T 1 9 4 9 H E W L E T T - P A C K A R O C O .