Heathkit AG 10 Schematic

Page 1

595-182

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SlNE-SQ'UA'RE
WAVE GENERATOR.

MODEL AG-IO

HEATH COMPANY

A Subsrdlury of Dayslrom Inc

BENTON HARBOR, MICHIGAN

Page 2

HELPFUL KIT BUILDING INFORMATION

Before attempting| actual liit construction read the cnuatmction
manual through t uroughly to familiarize yourself with the. general

adore. Note the relative location of pictorials and pictorial insert-
m rewpoct to the taupe-as of the assembly procedure outfitted.

Tbia information is olfered primarily for the mnvatienue of novice
tit builders and will he of definite assistance to those lacking tlrnmugh
knowledge of good constrmtion practices. Even the advanced elec-
tronics enthusiast may belxefil by a brii-l review of this material before.
prucreding with ltit maturation. In the majority of cases. failure to
nteerve basic instruction fundanwntah- is respxxnsihle for inability to
..htain desired level of perfumlance.

RECOMMENDED TOOLS

The sueoemlul coustmction of Heathkita does not require the use of
~ ializedequipmem and only bank: Inols are r aired. A good quality
rrmric soldrring iron is essential. The prd'errgd size would be a 100
watt iron with a small tip. The usa- of long nose pliers and d' ml or
nule cutting pliers is. recommended. A small acrew driver wil rave
adequate and several additional unsorted screw driver: will be be ful.
Be sure to obtain a good supply of rosin core type radio solder. ever
use separate fluxes, [ram or acid solder in electronic work.

ASSEMBLY
ln lhe actual mechanical assembly of minponentato the chassis and
[mm-l. it is important that the procedure shown in the manual he carfi
fully followed. Male sure that tube sockets are roperly mounted in
respect to keyway or pin numberim location. 'llhe same, applies to
trumfonner mountings m that the, correct transformer color coded
min-s will be available at the proper Chassis opening.

Make it a standard practice muse lnrlt washers under all 6-32 and
8452 nuts. The only eroeptiombeing in the use of solder lugs-the
neresoary locking feature as already incorporated in the design of the
colder large. A control lurk washer should always he used between the
mntml and the therein to prevent undesirable rotation in the panel.
To improve instrument appearance and to prevent. possible panel
warring use a control flat nwltel waahe: under each control nut.

W hen installing binding posts that require the. use of libel insulating
washers. it is good practice to slip the shudder washer over the bindingi
past mounting stud before iostallingethe niounti stud m the pane
lule provided. Next. install a flat ii wnnha an a solder lug under
the mounting ant. Be sure that the shoulder washer in properly
centered in the panel to prevent poaaible aborting of the binding post.

WIRING

When following wiring procedure malie the leads as xhnfl. and direct
as ptnaible. In filament wiring requiring the. use of a twisted pair of
wires allow auflicient alacl in the wiring that will wit the twisted
pair to be pushed a ainst the chain ea closely an possible. thereby
alluding relative ' ntion from adjacent parts and wiring.

When removing insulation from the end of huolul wire it isaeldorn
nmry to exrmse more than a qimrter inch of t wi . Bucmive
insulation removal may cause a short circuit condition in rapect to
nearby wiring or terminals. In some ilnltaricea. transformer leads of
solid per will have a brown halted enamel uniting. After the trans-
fomter ends have been trimmed to a suitable length. ill is many tn
srrape the enamel coating in order to expose the bright copper wire
before making a terminal or soldered mnnectitm.

In mounting parts BIICII aa reshtms or condensers. trim oif all exoua
lead length; so that the parts may he inutallrd in a direct. point-to-
pnint manner. When neeeawy use spaghetti or imulakd aleevmg over
uprated wires that might almrt to nearby guiding.

t is u ntly recommended that the Wiring rear; and parts layout
It shown In the construction manual he faithfully followed. In every
instance. the desirability of this arrangement was carefully determined
through the canatnrction of a series of laboratory models.

SOLDEIHNC

Much of the performance of the kit instnnnent. particularly in respect
to accumc and stability. depends upon the d ree of wukrpanahlp
used in mo in: soldered mnneetima. Proper sol red eorulectmas are
not at all dillicnlt to make but it would be adv'atable to observe a few
precautions. First of all More a mumiim is to be soldered. the
connedion itself should be clean and mechanically strong. Do not
de Id on solder alone to hold a connection legalize-z The tlipCol' the
wlfia' iron should be h t. clan and free of excess so r. Use
t to thoroughly ow the solder armothly into the oint.

enou I
Avoi exwasiveuseof solder and do not allowafluxfloodi coi itiou
to occur which could conceivably cause a leakage pat between

adjacent terminals on switch sesamhliea and tube socket. Thn 'n
partimlnrly important in instruments ouch as the V'fVM. oscillo-
ampe and generator hits. Excessive heat will also burn or damage the
insulating materialaised in I'm- manufaeture of xwitch assetnbllea.
Be sure lo uaeonly good quality main cure radio type solder.

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Page 6

through to the cathode of V-l and therefore lowering the output. A decrease in output would
affect the lamp in the opposite way, and increase the feedback and output.

The second cathode follower provides complete isolation between the oscillator and the output.

The attenuator supplies a 6009 output impedance up through the 1 volt position. The 10 volt
position has a variable impedance depending on the setting of the variable output control.

The "feedback" control varies the amount of feedback to the cathode of the 6086 and therefore
controls the strength of oscillation.

The "flatness adj." trims one side of the tuning capacitor to exactly the same capacity as the
other side. Small differences in capacity, especially at the full open positionof the timing capa-
citor, tend to make the output level change as the upper end of the calibrated frequency scale is
approached.

The "frequency adj. adds or subtracts capacity from both sideslof the tuning capacitor simul-
taneously. As can be seen from the "notch" formula, this raises or lowers the frequency.

The "distortion adj. " adjusts the bias, and therefore the operating point, of the 6CB6.
J;

SQUARE WAVE SECTION

The square wave section contains an input
cathode-follower, a "Schmitt Trigger Circuit",
an output cathode follower, and an attenuator
circuit.

The "input" cathode follower serves as an isola-
tion stage to keep the square waves from getting
back into the sine wave section. The sine wave
input to this tube is taken fromthe "Notch" net-
work, since this is the closest place on the chassis
where a sine wave is available.

The "output" cathode follower isolates the
"Schmitt Trigger Circuit", by acting as a step-
down impedance transformer. This is to keep
external connections from affecting the quality

of the square wave. =5 Schmitt Trigger Circuit

The "Schmitt Trigger Circuit" is, basically, amodification of the cathode-coupled mulivibrator,
except that the circuit action is a result of DC level changes and the circuit has no built-in time
constants. In this application, assuming no input signal, the input triode, V-5A, is normally
conducting and the output triode, V-5B, is normally cut off. As an input signal is applied to
the grid of V-5A, and starts going in a negative direction, the plate current starts to decrease,
therefore, increasing the plate voltage. Due to the 220K and 100 KB voltage divider, this in-
crease in plate voltage also increases the voltage at the grid of V-SB and starts to bring tint
stage out of its cut-off condition. As soon as V- 5B grid voltage increases to the point where
V-5B begins to conduct, its plate current increases the voltage across the 10 K9 common m
resistor.

This increase in cathode voltage decreases the plate current of V-5A still further, and theaction
of the previous steps quickly repeat themselves until V-5A is in a cut-off condition, and V-5B
is in saturation. The circuit stays in this condition until the input voltage at the grid of V-5A
returns again to the positive voltage that allows V-5A to begin conducting. When this happens,
the circuit acts the same way as described in the previous paragraph only in thereverse direc-
tion, and returns to the state it was in when we first assumed no input signal.

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Page 7

Thus it can be seen that a sine wave, triggering V-5A'on and off at a regular rate, will produce
square waves at the plate of V-5B. The negative portion of the square wave is when V-5B is
conducting, and the positive portion is when V-5B is cut-off. The vertical lines are the times
when the circuit is changing over from one state to the other.

The attenuator is designed for a 529 output impedance in the .1V and 1.0V position, and a vari-
able impedance in the 10V position, depending on the setting of the variable output control.

NOTES ON ASSEMBLY AND WIRING

This manual is supplied to assist you in every way to complete the instrument with the least
possible chance for error. We suggest that you take a few minutes now and read the entire man-
ual through before any work is started. This will enable you to proceed with the work much
faster when construction is started. The large fold-in pictorials are handy to attach to the wall
above your work space. Their use will greatly simplify the completion of the kit. These dia-
grams are repeated in smaller form within the manual. We suggest that you retain the manual
in your files for future reference, both in the use of the instrument and for its maintenance.

UNPACK THE KIT CAREFULLY AND CHECK EACH PART AGAINST THE PARTS LIST. In so
doing, you will become acquainted with each part. Refer to the charts and other information
shown on the inside covers of the manual to help you identify any parts about which there may
be a question. If some shortage is found in checking the parts, please notify us promptly and
return the inspection slip with your letter to us. Hardware items are counted by weight and if
a few are missing, please obtain them locally if at all possible.

Resistors and controls generally have a tolerance rating of :t 20% unless otherwise stated in the
parts list. Therefore a 100 K0 resistor may test anywhere from 80 K9 to 120 KS2. (The letter
K is commonly used to designatea multiplier of 1000. ) Tolerances on condensers are generally
even greater. Limits of +100% and -50% are common for electrolytic condensers. The parts
furnished with your Heathkit have been specified so as to not adversely affect the operation of
the finished instrument.

In order to expedite delivery to you, we are occasionally forced to make minor substitutions of
parts. Such substitutions are carefully checked before they are approved and the parts supplied
will work satisfactorily. By checking the parts
list for resistors, for example, you may find that
a 12009 resistor has been supplied in place of a
1 K9 as shown in the parts list. These changes
are self-evident and are mentioned here only to
prevent confusion in checking the contents of your
kit.

Most kit builders find it helpful to separate the
various parts into convenient catagories. Muffin
tins or molded egg cartons make convenient trays
for small parts. Resistors and capacitors may
be placed in the edge of a piece of corrugated
cardboard until they are needed. Values can be
written on the cardboard next to each component.
The illustration shows one method that may be
used. Read through the entire manual before
starting construction. In this way you will be-
come familiar with the techniques employed in
the building of your kit. As a further deterrent
to errors, read each step of the construction and
wiring completely before performing that step.

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Page 17

(

(

) Connect the long lead from TC-4 loosely to
terminal "I" (NS). (It maybe unhooked tem-
porarily during a later step.) Route this
lead close to the same corner as in the pre-
vious step.

) Carefully bend pin 1 of V-l out and down to-
ward the chassis. Connect a length of hook-
up wire from 13-6 (8-3) to pin 1 of V-1(S-1)
routing it close to the corner as in the pre-
vious steps.

This completes the wiring of the frequency deter-
mining network.

(

) Install the four binding posts on the front
panel as shown using binding post base,in-
sulators, solder lugs and 6-32 nuts. See
Figure 6 and Pictorial 1.

' \msuu'ron ausmnos.

ASSEMBLE SO PINS
INTERMESH AS
SHOWN

Figure 6

) Put the front panel in place and attach it to the chassis by mounting the 40052 control (with
the on/off switch) in the position indicated on the diagram. As was done in frequency mul-
tiplier switch, use a lockwasher between the control and chassis and a nickel washer be-

tween the panel and the control nut.
the next three controls at this time.

Do not tighten this control nut or the control nuts for

) In the same manner mount the following in the indicated positions, oriented as shown:
(a) Mount the three position switch (four terminals) in the square wave "range" position.
(b) Mount the four position switch (five terminals) in the sine wave range position, using

a control solder lug in place of the lockwasher.

the bottom of the panel.

Orient the lug straight down toward

(c) Mount the 10K control in the sine wave "amplitude" position.

(:1) Raise or lower the front panel position on the chassis until the tuning capacitor shaft
is centered in the hole in the front panel. While holding the frontpanel in this position,
tighten the control nuts on all four of the controls just installed.

) Install a #8 set screw in the insulated exten-
sion and in the pointer assembly. See Fig-
ure 7.

) Slide the insulated extension on the tuning
capacitor shaft with the small diameter end
facing forward, till it is roughly 1/ 16 in-
side the upper front shield, and tighten the
set screw. CAUTION: Do not let the set
screw rub against the shield.

) Slide the pointer assembly on the small end
of the insulated extension till the pointer
rests flat against the front panel. Do not
tighten the set screw at this time.

) Slide the large knob on the shaft in front of
the pointer and tighten the knob set screw.

) Insert the small red plug through the 1/8"
hole in the top of the panel. From the rear
of the panel, insert a screwdriver between
the three segments of the plug and widen the
opening so as to better admit light' from the
pilot lamp.

RED UG

PILOT LAMP
IAL POINTER

AL POINTER
SET SCREW

lNSlILAI'm
EXTENSION
SET 5

NSVLATED
EXTENSION

Figure 7

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