Method and apparatus for discriminatively determining electrical constants

An apparatus and method for determining electrical characteristics of an object wherein the phase difference between an input signal to and an output signal from a measuring circuit containing the object is maintained constant. Properties of the object are determined by monitoring the output of the measuring circuit of an amplitude signal related to the resistance of the object and by monitoring the output of the measuring circuit for an amplitude signal and a frequency signal related to the reactive impedance of the object.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the method and the apparatus for 
discriminatively determining various electrical constants, that is, 
capacitance, inductance, and resistance or its reciprocal of an object to 
be measured. 
2. Explanation of the Prior Art 
Since, from the point of view of equivalent circuit, any capacitance or 
inductive element necessarily contains a resistive part, when the 
capacitance or the inductance of those elements is measured, particularly 
when any continuous measurement of their variation is necessary, it is 
very difficult to exclude errors, that is, deviations from the true value 
due to their equivalent resistance part included. 
Particularly in the case that these values are measured in a 
material-constant measuring system such as in a continuous monitoring 
system for a liquid material flowing through a detection cell, it is 
desired to be capable of measuring the capacitance, inductance, and the 
resistance or its reciprocal discriminatively as well as simultaneously. 
However, heretofore neither apparatus nor method which can respond 
sufficiently to those desires has yet been proposed. 
SUMMARY OF THE INVENTION 
The present invention provides a method and apparatus to discirminatively 
determine electrical constants.

DETAILED EXPLANATION OF THE PREFERRED EMBODIMENT 
The gist of the method in accordance with a representative embodiment of 
the present invention is as follows: 
(1) The phase angle in the frequency transfer function of a measuring unit 
circuit which contains an object to be measured is maintained to a 
constant preset value. 
(2) For the purpose of this maintenance of the phase angle, a means 
detecting the phase difference between the input signal to said measuring 
unit circuit and the output signal therefrom is provided, and a variable 
frequency oscillator (voltage controlled) which is controlled by the 
resultant phase difference signal is placed in front of the measuring unit 
circuit, then with these structural elements a constant-value control loop 
is composed. 
(3) From this constant-value control loop the output signal of the 
measuring unit circuit is taken out, and then a resultant DC signal is 
utilized, after a differential amplification if necessary, as the signal 
for the resistance value or its reciprocal. 
(4) In the above case, it is also possible to obtain the signal for the 
resistance value or its reciprocal by detecting either the period or the 
frequency of the output of a voltage-to-frequency (or voltage-to-period) 
converter which is controlled by the abovementioned DC signal. 
(5) The abovementioned frequency signal is counted by a counter whose gate 
is controlled by the output signal from said variable frequency oscillator 
or by a signal of frequency of submultiple of the above frequency. The 
resultant count signal is further utilized as the capacitance or 
inductance part signal through a digital to analogue converter if 
necessary. 
(6) In the above case, since only the period itself is the necessary signal 
component for the gate-controlling signal to the counter, the output 
signal from the measuring unit circuit can also be utilized for the gate 
control. 
In the following, detailed explanations to more detailed configurations of 
the preferred embodiment in accordance with the present invention will be 
given referring to the attached drawings. 
FIG. 1 is a block diagram showing the outline of principle of the present 
invention, wherein G.sub.4 is a part comprising an object to be measured 
and a circuit part relating thereto. Let us call this part G.sub.4 the 
"measuring unit circuit". The object to be measured can be expressed with 
an equivalent circuit which generally includes resistive, capacitive and 
inductive elements. Then the measuring unit circuit is normally classified 
into several types according to the kind of their component elements of 
the object to be measured and the relating circuit part. Since all types, 
in principle, can be treated with a common procedure, the detailed 
explanation is given here only for a specific example wherein an 
equivalent circuit of an object to be measured consists of a parallel 
connection of a resistor and a capacitor. Examples of other types will be 
described later. 
In FIG. 1, G.sub.2 is a voltage controlled oscillator which feeds 
sinusoidal output voltage to the measuring unit circuit G.sub.4 through a 
current amplifier G.sub.3. Then an input voltage E.sub.I and an output 
voltage Eo of the measuring unit circuit G.sub.4 are both sinusoidal in 
the steady-state. Both of these sinusoidal waves are transformed into 
rectangular waves by waveform converters G.sub.5 and G.sub.6, then these 
rectangular waves are applied to a phase detector G.sub.7. A DC voltage 
proportional to the phase difference between the input sinusoidal voltage 
E.sub.I and the output sinusoidal voltage Eo is obtained as its output. 
This DC voltage is compared with a reference voltage V.sub.R1 by a summing 
point SP.sub.1 and its resultant difference is amplified by a differential 
operational amplifier G.sub.1. 
The voltage controlled oscillator G.sub.2 which is biased by a bias voltage 
V.sub.R2 fed through a summing point SP.sub.2 is controlled by the output 
voltage of the operational amplifier G.sub.1 in a manner that its 
oscillation frequency is changed so as to suppress the variation of the 
phase difference between the voltage and the current of the measuring unit 
circuit G.sub.4. Consequently this phase difference is always kept at a 
constant preset value. In this sense, this control scheme is categorized 
as the constant-value control. 
In the following, first, only the functional process of the present 
apparatus is described and after that the detailed operation principle is 
explained. Under the state previously described, the sinusoidal output 
voltage Eo of the measuring unit circuit G.sub.4 is transformed into a DC 
voltage E.sub.1/R by an AC-DC converter G.sub.8. The difference between 
this DC voltage E.sub.1/R and a zero-setting voltage V.sub.R17 is applied 
by a summing point SP.sub.3 to an operational amplifier G.sub.13, then in 
this case its output voltage is issued as a conductance part signal 
voltage E'.sub.1/R which is proportional to the conductance part of the 
object to be measured. Said output DC voltage E.sub.1/R of the AC-DC 
converter G.sub.8 is fed into a voltage-to-frequency converter G.sub.9. 
Hereupon, if a signal proportional to the resistance value itself is also 
desired, which is inversely proportional to the conductance value, a 
period T.sub.y (shown in the diagram or available at a terminal of a 
dotted line) of the output sinusoidal signal of the voltage-to-frequency 
converter G.sub.9 can be utilized, since T.sub.y is inversely proportional 
to E.sub.1/R. The output of said voltage-to-frequency converter G.sub.9 is 
fed into a counter G.sub.11 for counting its frequency f.sub.y. Meanwhile, 
the period of the output sinusoidal wave of G.sub.3, that is, the period 
of the input sinusoidal voltage E.sub.I to the measuring unit circuit 
G.sub.4, is utilized to generate a gate open time T.sub.x10 for the 
counter G.sub.11 through a period converter G.sub.10. As the result of 
this G.sub.11 works as not only a usual counter, but also performs 
arithmetic processing, i.e., multiplication, that its output count N 
becomes independent from a resistance part of the object to be measured 
and proportional only to a capacitance part of it, as will be shown by Eq. 
(13-3). This output count N is then converted into an analogue output 
quantity through a D-A converter G.sub.12 and is issued as a capacitance 
part signal voltage Eo. 
Next, the theoretical explanation to the operation principle of the 
apparatus having above-described circuit construction is given in the 
following. 
(1) Circuit construction of the measuring unit circuit G.sub.4 : 
A circuit construction of the measuring unit circuit including an object to 
be measured which is expressed by an equivalent circuit of a parallel 
connection of a capacitance C and a resistance R is such as shown in FIG. 
2A. 
Here, a part surrounded by a dotted line is the object to be measured. 
First the values of R, C and an input voltage E.sub.I are assumed to be 
those in the steady-state. In this case E.sub.I is written as 
EQU E.sub.I =.vertline.E.sub.I .vertline.e.sup.j.omega..sbsp.x.sup.t, 
where .vertline.E.sub.I .vertline. is the amplitude and .omega..sub.x is 
the angular frequency of the input voltage, respectively. Also, amplifiers 
A.sub.5 and A.sub.6 are assumed to be ideal ones, that is, the following 
conditions 
Input impedance=.infin. 
Open loop gain=.infin. 
Phase rotation=0 
are assumed. Then, let us define a transfer function K.sub.4 of the 
measuring unit circuit G.sub.4 as: 
EQU K.sub.4 =Eo/-E.sub.I =(1/R+j.omega..sub.x C)R.sub.f (1), 
where Eo is an output voltage and R.sub.f is a feedback resistance. Since 
the phase-angle between the input and the output voltages of G.sub.4 is 
given by 
EQU .theta.=tan.sup.31 1 .omega..sub.x .multidot.C.multidot.R (2). 
If this phase angle can be kept constant, then the following relation 
EQU C.varies.1/.omega..sub.x .multidot.1/R (3) 
is established. Therefore, it is understood that, by measuring 1/R and 
1/.omega..sub.x and taking their mutual product, a value of C can be 
obtained therefrom. 
(2) Prerequisite condition of the constant-value control: 
The partial differential coefficients of the phase angle .theta. expressed 
by Eq. (2) with respect to .omega..sub.x, C, and R are given, respectively 
by 
##EQU1## 
Since the total differential d.theta. of the phase angle .theta. is 
defined as 
EQU d.theta.=K.omega..sub.x .multidot.d.omega..sub.x +Kc.multidot.dC+K.sub.R 
.multidot.dR 
the increment .DELTA..theta. of .theta. is written as follows by using the 
increments .DELTA..omega..sub.x, .DELTA.C and .DELTA.R of .omega..sub.x, C 
and R, respectively: 
EQU .DELTA..theta..apprxeq.K.omega..sub.x .multidot..DELTA..omega..sub.x 
+Kc.multidot..DELTA.C+K.sub.R .multidot..DELTA.R. 
Then, under the condition of the steady-state, those partial differential 
coefficients K.sub.107.sbsb.x, Kc, and K.sub.R given in Eqs.(4), (5) and 
(6) can be treated similarly as for the transfer functions. 
When no integration unit circuit is included in the composing unit circuits 
of the circuit shown in FIG. 1, time constants of those unit circuits are 
very small and dead times of them are also very short ones, and moreover 
since the time variation of the signal is very slow, all the included unit 
circuits can be regarded to be of zero order. 
Therefore, transfer functions of all the included unit circuits Gn (n=1, . 
. . , 13, except n=4) can be expressed as real constants Kn (n=1, . . . , 
13, except n=4), and under this assumption the following explanation is 
given. 
(3) Constant-value control of the phase angle .theta.: 
A functional block diagram of the constant value control loop of FIG. 1, on 
which the present invention is based, is shown in FIG. 3. Here, V.sub.R1 
is the command of the control, that is, the phase angle setting voltage, 
and .theta. is the controlled variable. Kp inclusively represents K.sub.1, 
K.sub.2, and K.sub.3, and K.omega..sub.x, Kc, and K.sub.R are those 
defined in the above Eqs.(4), (5) and (6), respectively. 
The control system of FIG. 3 can be expressed by the following equation: 
EQU (V.sub.R1 -K.sub.7 .multidot..DELTA..theta.)Kp.multidot.K.omega..sub.x 
+{(Kc.multidot..DELTA.C+K.sub.R .multidot..DELTA.R)}=.DELTA..theta.(7). 
Here, if the second parenthesis term of the left hand side of Eq.(7) may be 
regarded as the disturbance in a control loop, then letting this term be a 
disturbance D (D=Kc.multidot..DELTA.C+K.sub.R 
.multidot..DELTA.R=.DELTA..theta..sub.C +.DELTA..theta..sub.R), and also 
setting the command V.sub.R1 to zero for simplicity of the explanation, 
then from the above Eq.(7), .DELTA..theta. in this case is given as 
EQU .DELTA..theta.=1/(1+Kp.multidot.K.omega..sub.x 
.multidot.K.sub.17).multidot.D. 
Hereupon, since Kp.multidot.K.omega..sub.x .multidot.K.sub.7 means the 
open-loop transfer function F, then .DELTA..theta. may be written as 
EQU .DELTA..theta.=1/(1+F).multidot.D (8). 
Thus for a very large value of F, 
EQU .DELTA..theta..apprxeq.0 (8'). 
Moreover, if at least a single integration unit circuit is added to the 
loop for increasing the stability of the loop, it is possible to make the 
steady-state residual offset .DELTA..theta..sub.ss of .DELTA..theta. to be 
zero. Since the addition of the integration unit circuit is a conventional 
measure in the control loop, the integrator unit circuit is omitted for 
the sake of simplicity. 
(4) Signal conversion and arithmetic processing system: 
(i) The output frequency f.sub.y of the voltage-to-frequency converter 
G.sub.9 and the output of the AC-DC converter G.sub.8, that is, the 
conductance part signal E'.sub.1/R : 
A functional block diagram of only this part in the whole circuit of FIG. 1 
is shown in FIG. 4, and its function is expressed by the following 
equation; 
EQU E.sub.1/R =K.sub.8 .multidot..vertline.Eo.vertline. (9-1), 
where .vertline.Eo.vertline. is the amplitude of the output of G.sub.4. 
Here, if the value of V.sub.R17 is taken to be V.sub.R17 =0, then the 
conductance signal E'.sub.1/R becomes 
EQU E'.sub.1/R =K.sub.8 .multidot.K.sub.13 
.multidot..vertline.Eo.vertline.(9-2), 
and the output frequency f.sub.y of G.sub.9 is given by 
EQU f.sub.y =K.sub.9 .multidot.E.sub.1/R (9-3). 
(ii) The output of the period converter G.sub.10, that is, the gate open 
time T.sub.x10 : 
Only the relevant part of the whole circuit of FIG. 1 is shown in FIG. 5, 
and its function is expressed by the following equation; 
EQU T.sub.x10 =K.sub.10 .multidot.T.sub.x (10), 
where T.sub.x is a period of the output sinusiodal wave of the voltage 
controlled oscillator G.sub.2. 
(iii) The capacitance part signal voltage Ec: 
Similarly as in the preceding items, this part is shown in FIG. 6 and its 
function is expressed by 
EQU N=f.sub.y .multidot.T.sub.x10 (11-1), 
where N is the count by the counter G.sub.11 of output pulses of G.sub.9 in 
a time interval of said gate open time T.sub.x10. In this case, the 
function of G.sub.11 is that of a multiplier whose input signals are a 
frequency and a time interval as expressed by Eq.(11-1). 
Therefore, the output of the D-A converter G.sub.12, that is, the 
capacitance part signal voltage E.sub.C is given by 
EQU Ec=K.sub.12 .multidot.N (11-2). 
(5) Relation between the measured quantity and the output signal of the 
apparatus: 
(i) Relation between the conductance 1/R and its output signal E'.sub.1/R : 
The amplitude .vertline.Eo.vertline. of the output voltage Eo of the 
measuring unit circuit G.sub.4 can be expressed as 
##EQU2## 
Substitution of .vertline.Eo.vertline. given by the above equation into Eq. 
(9-2) yields 
##EQU3## 
and since .theta.=tan .sup.-1 .omega..sub.x C.multidot.R, that is since 
.sqroot.1+(.omega..sub.X R.multidot.C).sup.2 =sec.theta., from Eq. (2), 
then Eq. (12-2) becomes 
EQU E'.sub.1/R =K.sub.8 .multidot.K.sub.13 .multidot.R.sub.f 
.multidot..vertline.E.sub.I .vertline. sec.theta.1/R (12-3) 
Here letting .kappa..sub.1/R =K.sub.8 .multidot.K.sub.13, then 
EQU E'.sub.1/R =.kappa..sub.1/R .multidot.R.sub.f .multidot.E.sub.I 
.vertline.sec.theta..multidot.1/R (12-4). 
Letting .theta.o be a phase angle at the balance state of the constant 
value control loop, that is, at the time when the controlled quantity 
becomes equal to its command and hence the offset becomes zero, the phase 
angle can be written in general as 
EQU .theta.=.theta.o+.DELTA..theta.. 
Under the condition of a large value of open loop transfer function F, 
.DELTA..theta..apprxeq.O holds as in Eq. (8)', therefore Eq. (12-4) 
becomes 
EQU E'.sub.1/R =.kappa..sub.1/R .multidot.R.sub.f .multidot..vertline.E.sub.I 
.vertline..multidot.sec.theta..sub.o .multidot.1/R (12-5). 
Then, it is understood from this equation that for an appropriately given 
fixed value of the feed back resistance R.sub.f the conductance part 
output signal voltage E'.sub.1/R can be kept approximately proportional to 
the conductance 1/R provided that the amplitude of the input voltage 
E.sub.I to the measuring unit circuit is kept constant. 
Practically the measuring control loop expressed with the approximate 
equality equation (12-5) can be applied for most cases, but it also a 
conventional measure to stabilize the loop by adding more than one 
integration unit circuit, and in this case the steady-state offset 
.DELTA..theta..sub.ss becomes zero and hence Eq. (12-5) holds exactly. 
(ii) Relation between the capacitance C and its output signal Ec: 
Starting from Eq. (11-2), it can be shown that Ec is proportional only to 
C. The explanation thereto is given in the following. First substitution 
of Eq. (11-1) into Eq. (11-2) yields 
EQU Ec=K.sub.12 .multidot.f.sub.y .multidot.T.sub.y10, 
then with Eq. (10) 
EQU Ec=K.sub.12 .multidot.f.sub.y .multidot.K.sub.10 .multidot.T.sub.x, 
also with Eq. (9-3) 
EQU Ec=K.sub.12 .multidot.K.sub.9 .multidot.E.sub.1/R .multidot.K.sub.10 
.multidot.T.sub.x, 
further this can also be rewritten by Eq. (9-1) as 
EQU Ec=K.sub.12 .multidot.K.sub.9 .multidot.K.sub.8 .multidot..vertline.E.sub.o 
.vertline..multidot.K.sub.10 .multidot.T.sub.x (13-1). 
Hereupon, since 
EQU T.sub.x =2.pi./.omega..sub.x, 
then substituting Eq. (12-1) together with the above relation into Eq. 
(13-1), the following equation is given: 
##EQU4## 
Here letting 
EQU K.sub.8 .multidot.K.sub.9 .multidot.K.sub.10 .multidot.K.sub.12 
=.kappa..sub.c, 
then Eq. (13-2) is rewritten as 
##EQU5## 
Modifying the right hand side of Eq. (13-2)' as 
##EQU6## 
and using the following relation 
##EQU7## 
which is obtained from Eq. (2), then Ec is expressed as 
EQU Ec=2.pi..multidot..kappa..sub.c .multidot.R.sub.f 
.multidot..vertline.E.sub.I .vertline..multidot.cosec .theta..multidot.C. 
Therefore, similarly as in the case of the conductance part described 
previously, making .DELTA..theta..fwdarw.0 and taking the steady-state 
offset to be zero, Ec is finally expressed as 
EQU Ec=2.pi..multidot..kappa..sub.c .multidot.R.sub.f .multidot.E.sub.I 
.vertline..multidot.cosec .theta..sub.o .multidot.C (13-3) 
Here, since the right hand side of Eq. (13-3) does not include any term of 
1/R, it is clear that Ec is independent of the conductance and is 
proportional only to the capacitance C. 
(6) Other configuration of the measuring unit circuit: 
In the above, the explanation was given to the case where the object to be 
measured is expressed as an equivalent circuit of the parallel connection 
of R and C as shown in FIG. 2A. There exist still other sorts of object to 
be measured which are expressible with different equivalent circuits from 
that of already explained case. Corresponding to those different sorts of 
the object to be measured, the circuit construction of the measuring unit 
circuit is also different as shown by FIGS. 2B to 2D and classified as 
follows: 
(i) The case of an equivalent circuit of a series connection of a 
capacitance C and a resistance R (the case shown by a part of dotted line 
box in FIG. 2B). 
(ii) The case of an equivalent circuit of a parallel connection of an 
inductance L and a resistance R (FIG. 2C). 
(iii) The case of an equivalent circuit of a series connection of an 
inductance L and a resistance R (FIG. 2D). 
The explanation is given to those cases mentioned above. For those cases, 
the relation between the frequency transfer function K.sub.4 and the phase 
angle .theta. of the measuring unit circuit is shown in the following 
table, together with the relation of cases (0), which has been described 
above, for comparison. 
______________________________________ 
corre- 
spond- 
ing 
circuits 
shown 
in 
K.sub.4 .theta. FIG. 
______________________________________ 
##STR1## tan.sup.-1 .omega..sub.x C .multidot. R 
2A 
##STR2## 
##STR3## 2B 
ii 
##STR4## 
##STR5## 2C 
iii 
##STR6## 
##STR7## 2D 
______________________________________ 
In this table, by comparing the dependencies of K.sub.4 and .theta. with 
respect to .omega..sub.x for those cases of (i), (ii), and (iii) with that 
for the case of (0), it will be understood that if the 
voltage-to-frequency converter G.sub.9 in FIG. 1 for the case (0) is 
replaced by a voltage-to-period converter for the cases (i) and (ii), 
almost the same treatment as for the case (0) can also be applied to the 
cases (i) and (ii). For the case (iii), the substitution of G.sub.9 
mentioned above above is not necessary. 
Hereupon Eo is proportional to R for the cases (i) and (iii), while it is 
proportional to 1/R for the cases (0) and (ii). Therefore, depending upon 
the object to be measured, either one should be selected. 
Besides the above-mentioned modified circuit examples, still different 
circuits, for example, a circuit wherein a parallel connection of R and C 
is placed in the feedback path of an amplifier may be considered. In this 
case the transfer function and the phase angle are given respectively as 
1/(R.sub.1 (1/R+j.omega..sub.x .multidot.C)) and -tan .sup.-1 
.omega..sub.x .multidot.C.multidot.R, then the signal processing 
thereafter is the same as for the case (i). 
Operation of the abovementioned example: 
First, the referrence voltage sources V.sub.R1 and V.sub.R2 are set in such 
values to select the phase difference .theta. of the input and output 
signals of the measuring unit circuit G.sub.4 to be a specified set value 
.theta..sub.o other than 0.degree.. 
Then the frequency .omega..sub.x /2.pi. of the voltage-controlled 
oscillator G.sub.2 is automatically adjusted by the action of the 
constant-voltage control loop so as to make the phase difference the 
abovementioned set value .theta..sub.o. After this setting of 
.theta..sub.o, the operation is automatically processed in accordance with 
the operation principle described above, and the D-A converter G.sub.12 
issues the value indicating the capacitance C. Also be setting the zero 
point by adjusting the variable resistor V.sub.R17, the value E'.sub.1/R 
indicating the reciprocal of the resistance R is given from the 
differential amplifier G.sub.13. 
FIG. 7 shows an example of more specifically represented circuit for the 
apparatus of FIG. 1, wherein A.sub.1 corresponds to SP.sub.1 and G.sub.1 ; 
A.sub.2 to SP.sub.2 ; VCO to G.sub.2 ; A.sub.4 to G.sub.3 ; R,C,A.sub.5 
and A.sub.6, to G.sub.4, A.sub.8 to G.sub.6, PD and a circuit LPF 
including A.sub.10 surrounded by the dotted line box to G.sub.7, a circuit 
AC-DC including, A.sub.13 and A.sub.14 inside the other dotted line box to 
G.sub.8 ; A.sub.11 and A.sub.12 to G.sub.5 ; D to G.sub.10 ; A.sub.15 and 
V-F to G.sub.9 ; CT to G.sub.11 ; D-A and A.sub.16 to G.sub.12 ; and then 
A.sub.17 corresponds to SP.sub.3 and G.sub.13, respectively. A.sub.3, 
A.sub.7, A.sub.9 and A.sub.11 are buffer amplifiers. From a terminal 
OUT.sub.1 the capacitance part signal is issued, while from a terminal 
OUT.sub.2 the conductance part signal is issued. Also a reference voltage 
source S for supplying the voltages V.sub.R1, V.sub.R2, V.sub.R15 and 
V.sub.R17 is provided. The voltage V.sub.R15 is a bias for A.sub.15. 
A simulation experiment by using an apparatus of the circuit of FIG. 7 
which was constructed with those parts shown in the following parts list 
was made and the function of the present invention has been confirmed. 
______________________________________ 
Parts List 
Symbol Type Maker 
______________________________________ 
A.sub.1 AD520J Analog Devices 
A.sub.2,A.sub.15,A.sub.16,A.sub.17 
LM725 National Semiconducter 
Corp. 
VCO, V-F 8038CC Intersil Inc. 
A.sub.3,A.sub.7,A.sub.9,A.sub.11 
LM310 National Semiconductors 
Corp. 
A.sub.4,A.sub.6 
LH0002 National Semiconductors 
Corp. 
A.sub.5 AM405 Datel Systems Inc. 
A.sub.8,A.sub.12 
.mu.A734 Fairchild Semiconductors 
PD MC4044 Motrola Semiconductors 
A.sub.10,A.sub.13,A.sub.14 
LM301A National Semiconductor 
Products Inc. 
MC14522,MC14051 
D MC14518 and Motrola Semiconductor 
Digital switch 
Products Inc. 
MC14510 
CT Motrola Semiconductor 
MC14508 Products Inc. 
D-A AD563J/BCD Analog Devices 
______________________________________