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TTS 26B
Section 4
the spark s u p p r e s s o r s on the DRIVE relay contacts,
4.21 Loop o r
E&M
signals a r e connected to the
the t r a n s f e r time of the SEND relay i s kept low
appropriate SEND jacks by the SEND switch in
under all conditions.
In order to permit use of
the following manner in clockwise sequence:
the TTS 26B for switching of voice frequency
circuits, the spark s u p p r e s s o r s can be omitted
a.
SEND LOOP REC B&G: A pulsing open
f r o m the contacts of the SEND relay by operating
o r short condition i s applied to the tip and
the SPARK SUP turnbutton switch to OFF.
If the
ring of the LOOP SIGNALING-SEND 1 and 2
TTS ' 2 6 ~
i s to be used on high power or highly
jacks for circuits which provide battery and
inductive c i r c u i t s , the internal spark suppressor
ground.
circuit should be used.
Access to the a r m a t u r e ,
make, and b r e a k contacts of the SEND relay i s
b.
SEND LOOP REC LOOP: When the SEND
obtained on the tip, ring,
and
sleeve of the SEND
turnbutton switch i s in the R T ON 1
&2
posi-
RELAY
jack.
tion, a pulsing open o r short condition i s
applied to the tip and ring of the LOOP SIG-
NALING-SEND 1 and 2 jacks f o r c i r c u i t s
which provide battery and ground.
When
the SEND hrnbutton switch i s i n the SLE-
EVES position, the amature of the SEND
relay i s connected to the sleeve of the
LOOP SIGNALING SEND LOOP 2; the on
hook contact of the SEND relay to the sleeve
of the LOOP SIGNALING SEND LOOP 1;
and the off hook contact to the sleeve of the
REC LOOP jack.
In this condition no con-
nections a r e made to the T and R leads of
SEND LOOP jacks 1 and 2 .
CAUTION
If the TTS 26B SEND circuits will be switching
currents of m o r e than 100rnA, voltages in
excess of 50 volts, o r inductive circuits, the
internal
SPARK
SUP turnbutton should be
operated to ON.
This internal suppressor
circuit, when connected, protects the SEND
relay contacts with a r c reduction networks of
0 .
l p F and 220Q. These values a r e generally
satisfactory for standard 48 relay switching
circuits.
C a r e must be used when spark
suppression is added that the performance of
the c i r c u i t s under test i s not affected by the
spark suppression circuit.
PULSES P E R
SEC
control to the position c o r r e -
sponding to the speed of the dial used-
4 . 1 9 The internal oscillator i s a convential,
transistorized, sine wave oscillator equipped
with a buffer amplifier to provide the desired
signal level to operate the DRIVE relay. When
the external dial i s used to control the SEND relay
the operation of the dial-causes the DIAL relay to
operate.
The armatureofthisrelayappliesbattery
or ground to a low pass filter.
The output of the
low pass f i l t e r has the sloping waveform which
is necessary to obtain proper bias control i n the
DRIVE r e l a y .
To obtain maximum range of con-
trol, the f i l t e r condenser in the low pass filter
should be switched to correspond to the dial
speed.
This i s automatically done by turning the
4.20 When pulsing signals a r e generated by the
internal oscillator, these signals a r e applied
to the DRIVE relay directly by the SEND AND
TEST key switch. When these signals a r e gener-
ated externally, i t i s also necessary to use the
EXT
DIAL CIRCUIT switch and s e t i t in the posi-
tion applicable to the external circuit conditions
:
fig. 3 shows the circuit connections which may
be established under control of this switch. A
further explanation of the use of the EXT
DIAL
CIRCUIT switch i s presented in paragraph 4 . 2 1 .
c.
LINE (M =B&G, E =G&O): Signaling
with battery and ground applied to the
M
lead on the ring of the
LINE
jack and on the
M jack.
The battery i s supplied through a
resistance lamp.
d.
DROP ( M =B&G,
E =G&O): Signaling
with ground and open applied to the E lead
on the tip of the DROP jack.
e .
LINE
(M =B&O, E =G&O): Signaling
with battery and open applied to the M lead
on the ring of the LINE jack and on the M
jack.
The battery i s supplied through a
r e s i s t a n c e lamp.
f .
DROP ( M =B&O, E =G&O): Signaling
with ground and open applied to the E lead
on the tip of the DROP jack.
The receive functions of the combined SEND and
RECEIVE operations a r e covered i n paragraph
4.9.
4.22 An additional loop signaling arrangement i s
provided i n which battery and ground a r e applied
to an external "drytt circuit under control of the
SEND relay.
This arrangement i s available on
the
SEND B&G jack under LOOP SIGNALING
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