Build your own TV
you will need for this installment:
Power supply components
one with a switch
Front and rear panel material
the previous installment you were given three circuit diagrams, the Video/Sync
circuit, the Phase Comparator/Motor Driver and the Audio Amplifier. The first
two are powered by a 15-volt DC source and the Audio Amplifier requires a 12-volt
source. The schematic for the two DC sources is shown here on the right. The supplies are identical
except for the regulator I.C. which is a type 7815 regulator in the 15-volt source
and a type 7812 in the 12-volt source. Both regulator I.C.s are fitted with small
Since I used printed circuit boards
to contain the various components, I included the power supply components ( minus
the transformers) on each of the three boards. You might prefer to use separate
small pieces of vector board for these parts.
are a number of choices available to you when building the power supplies. One
"large" power transformer can be used to supply the entire load or two
or three smaller ones can do just as well. "Large" is a relative term
here, in that relatively small transformers are required in any case.
my own situation, I used two transformers, the larger of the two rated at 17 volts,
.35 amperes. It supplies the 15-volt D.C. circuits. The other transformer was
rated at 14 volts at .2 amperes and it supplies the Audio Amplifier only. One
17 volt transformer with a .5 ampere rating could also have be used to supply
all three circuits, in which case a slightly larger heat sink on the 7812 regulator
might be necessary.
Transformers with up to
20-volt outputs can be used, but more heat will be dissapated by the regulators,
so larger heat sinks will be necessary.
haven't already done so on your own, you might now install the four controls on
a section of aluminum angle or wooden equivalent and mount the assembly on the
base of the cabinet. Here is a photo showing the receiver construction.
at the front of the cabinet, starting from the left, the controls are the Volume
(and switch), the Contrast, the Brightness and the Motor Speed. The shafts on
the controls should be long enough to pass through and an additional 3/8"
to 1/2" beyond the front panel.
haven't made up a front panel yet, do it now. I used 1/8" thick black Micarta,
which looks like Bakelite. Wood, metal or plastic are all suitable. The rear panel
can be the same material as the front panel. On it, you can mount the main power
toggle switch and a hole for the line cord. Two RCA jacks for the input video
and sound signals are also mounted on the rear panel. In my case, I used a section
of 3/4" X 2" aluminum angle for the rear panel.
might now mount the transformer(s), circuit assemblies and speaker in appropriate
locations. Keep in mind that the scanning disk will be passing through the cabinet
when the set is operating. If you place the two top covers on the cabinet, there
will be an approximate 1/2" gap between them. This is where the scanning
disk will be located. You do not want any of the parts in the cabinet to interfere
with the operation of the scanning disk. Stay at least a 1/2" away from where
the disk will be at all points.
the inside of the cabinet, you will need a termination for the motor and LED array
wiring, mounted on the TOP, rear surface. I used four pins of a small five-pin
male/female connector. The female part is on a short length of angle bracket,
mounted on the side panel. The male part of the connector is on about six inches
of cable attached to the rear TOP underside surface.
you have all of the parts except the sync fork in place in the cabinet, you can
begin wiring the Audio Amplifier to the 12-volt supply and the volume control.
Then continue by getting the 15 volt supply working. The Audio Amplifier can be
easily tested with inputs from signal generators, radios or phono pickups. If
you have an oscilloscope, it will be the best instrument for testing the circuits
in the monitor. When you are satisfied that the power supplies and audio amplifier
working, don't do any further wiring until the motor, disc bearing assembly and
LED array are set up on the top rear cover. That will be covered in the next installment.
This message is to
those of you that are building your monitor, per these installments.
next installment, number eight will most likely complete the construction of the
monitor. Following that, there will be one additional installment on the subject
of troubleshooting. I also wish to develop an FAQ (frequently asked questions)
based on questions from the readership,(that's you!) that I will try to answer
and place these on this site.
This might also
be a time to consider where you are going to get a 32 line television signal to
operate this monitor. For those of you that are patient, I plan to begin a series
of installments on a 32 line camera, most likely of the direct view variety. However
if you are in a hurry (as I would be), I strongly recommend you contact the NBTVA
( there is a link on this site) and purchase one of their CDs (second version).
Do yourself a favor and join their club at the same time.
if you have questions of me, write or Email me, as of now.
you for your interest.
yourdisk zworykin tv_build9