Vectronics VEC-483K User Manual
VEC-483K Owner’s Manual Voice Activated Tape Recorder Switch
INTRODUCTION
General Information: Ever wish you could edit the "dead air time" from tape
recordings of meetings, speeches, interviews, etc? Now you can do it while you
record with the VEC-483K Voice Activated Tape Recorder Switch Kit. With
voice activation, you save money by recording more information on each tape-and you save valuable listening time during playback because every inch of tape
is filled with information. In addition to voice-activating your recorder, the
VEC-483K helps you make better quality recordings because it places a highquality electret microphone near the sound source, and far away from the noisy
tape transport mechanism in your machine.
Circuitry: The VEC-483K has two parts. First, a sensitive electret microphone
picks up sound and sends it to your recorder via the external microphone jack.
Second, a high-gain op-amp samples the microphone signal, amplifies it, and
then detects it--using the detector level to drive a FET switch. This switch, in
turn, activates and pauses your recorder via the remote jack. Sensitivity and
hold-delay are both adjustable to your liking. The unit is internally powered by a
long-lasting 9-volt alkaline battery.
TOOLS AND SUPPLIES
Construction Area: Kit construction requires a clean, smooth, and well-lighted
area where you can easily organize and handle small parts without losing them.
An inexpensive sheet of white poster board makes an excellent construction
surface, while providing protection for the underlying table or desk. Diffused
overhead lighting is a plus, and a supplemental high-intensity desk lamp is
especially helpful for close-up work. Safety is always important! Use a suitable
high-temperature stand for your soldering iron, and keep the work area free of
clutter.
Universal Kit-building Tools: No special tools are required to complete this
kit beyond common items normally used for bench construction. We
recommend the following:
! Soldering Iron (grounded-tip and temperature-controlled preferred)
! High-temperature Iron Holder with Cleaning Sp onge
! Solder, 60/40 or 63/37 with rosin or "no-clean" flux (.031" dia. is good
size).
! Needle Nose Pliers or Surgical Hemostats
! Diagonal Cutters or "Nippy Cutters"
! Solder Sucker (squeeze or vacuum pump type), or Desoldering Braid
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VEC-483K Owner’s Manual Voice Activated Tape Recorder Switch
! Bright Desk Lamp
! Magnifying Glass
BEFORE YOU START BUILDING
Experience shows there are four common mistakes builders make. Avoid these,
and your kit will probably work on the first try! Here's what they are:
1. Installing the Wrong Part: It always pays to double-check each step. A 1K
and a 10K resistor may look almost the same, but they may act very
differently in an electronic circuit! Same for capacitors--a device marked
102 (or .001 uF) may have very different operating characteristics from one
marked 103 (or .01uF).
2. Installing Parts Backwards: Always check the polarity of electrolytic
capacitors to make sure the positive (+) lead goes in the (+) hole on the
circuit board. ICs have a notch or dot at one end indicating the correct
direction of insertion. Always double-check--especially before applying
power to the circuit!
3. Faulty Solder Connections: Inspect for cold-solder joints and solder
bridges. Cold solder joints happen when you don't fully heat the connection-or when metallic corrosion and oxide contaminate a component lead or pad.
Solder bridges form when a trail of excess solder shorts pads or tracks
together (see solder tips below).
4. Omitting or Misreading a Part: This is easier to do than you might think!
Always double-check to make sure you completed each step in an assembly
sequence.
Soldering Tips: Cleanliness and good heat distribution are the two secrets of
professional soldering. Before you install and solder each part, inspect leads or
pins for oxidation. If the metal surface is dull, sand with fine emery paper until
shiny. Allow the tip of your iron to contact both the lead and pad for about one
second (count "one-thousand-one") before feeding solder to the connection.
Surfaces must become hot enough for solder to flow smoothly. Feed solder to
the opposite side of the lead from your iron tip--solder will wick around the lead
toward the tip, wetting all exposed surfaces. Apply solder sparingly, and do not
touch solder directly to the hot iron tip to promote rapid melting. Keep a damp
sponge handy to wipe your so ldering tip on. This removes excess solde r, and
keeps the tip properly tinned. If the iron is going to sit idling for long periods,
wipe the tip, add some fresh solder, and unplug the iron.
Desoldering Tips: If you make a mistake and need to remove a part, follow
these instructions carefully! First, grasp the component with hemostats or
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VEC-483K Owner’s Manual Voice Activated Tape Recorder Switch
needle-nose pliers. Heat the pad beneath the lead you intend to extract, and pull
gently. The lead should come out. Repeat for the other lead. Solder may fill in
behind the lead as you extract it--especially if you are working on a double-sided
board with pla te-through holes. Should this hap pen, try heating the pad again
and inserting a common pin into the hole. Solder won't stick to the pin's
chromium plating. When the pad cools, remove the pin and insert the correct
component. For ICs or multiple-pin parts, use desoldering braid to remove
excess solder before attempting to extract the part. Alternatively, a low-cost
vacuum-bulb or spring-loaded solder sucker may be used. Parts damaged or
severely overheated during extraction should be replaced rather than reinstalled.
Work Habits: Kit construction requires the ability to follow detailed
instructions and, in many cases, to perform new and unfamiliar tasks. To avoid
making needless mistakes, work for short periods when you're fresh and alert.
Recreational construction projects are more informative and more fun when you
take your time. Enjoy!
Sorting and Reading Resistors: The electrical value of resistors is indicated by
a color code (shown below). You don't have to memorize this code to work with
resistors, but you do need to understand how it works:
Resistor Color Code
Black = 0 (tens)
1st Digit
2nd Digit
Multiplier
Tolerence
(gold or silver)
When you look at a resistor, check its multiplier code first. Any resistor with a
black multiplier band falls between 10 and 99 ohms in value. Brown designates
a value between 100 and 999 ohms. Red indicates a value from 1000 to 9999
ohms, which is also expressed as 1.0K to 9.9K. An orange multiplier band
designates 10K to 99K, etc. To inventory resistors, first separate them into
groups by multiplier band (make a pile of 10s, 100s, Ks, 10Ks, etc.). Next, sort
each group by specific value (1K, 2.2K, 4.7K, etc). This procedure makes the
inventory easier, and also makes locating specific parts more convenient later on
during construction. Some builders find it especially helpful to arrange resistors
in ascending order along a strip of double-sided tape.
Reading Capacitors: Unlike resistors, capacitors no longer use a color code for
value identification. Instead, the value, or a 3-number code, is printed on the
body.
Brown = 1 (hundreds)
Red = 2 (K)
Orange = 3 (10K)
Yellow = 4 (100K)
Green = 5 (1Meg)
Blue = 6
Violet = 7
Gray = 8
White = 9
Silver = 10%
Gold = 5%
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VEC-483K Owner’s Manual Voice Activated Tape Recorder Switch
Value Code
10 pF = 100
100 pF = 101
1000 pF = 102
.001 uF = 102*
.01 uF = 103
.1 uF = 104
As with resistors, it's helpful to sort capacitors by type, and then to arrange them
in ascending order of value. Small-value capacitors are characterized in pF (or
pico-Farads), while larger values are labeled in uF (or micro-Farads). The
transition from pF to uF occurs at 1000 pF (or .001 uF)*. Today, most
monolithic and disc-ceramic capacitors are marked with a three-number code.
The first two digits indicate a numerical value, while the last digit indicates a
multiplier (same as resistors).
Electrolytic capacitors are always marked in uF. Electrolytics are polarized
devices and must be oriented correctly during installation. If you become
confused by markings on the case, remember the uncut negative lead is slightly
shorter than the positive lead.
Integrated Circuits: Proper IC positioning is indicated by a dot or square
marking located on one end of the device. A corresponding mark will be silkscreened on the PC board and printed on the kit's parts-placement diagram. To
identify specific IC pin numbers for testing purposes, see the diagram below.
Pin numbers always begin at "1" at the keyed end of the case and progress along
the device, as shown:
Multilayer
(270 pF)
271
Ceramic Discs
(.001 uF) (.1 uF)
102
104
Electrolytic
1 uF
|
1uF
|
35V
+
-
8 7 6 5
Installation
Key
1 2 3 4
Pin Numbers
Installation
Key
PARTS LIST
Your kit should contain all of the parts listed below. Please identify and
inventory each item on the checklist before you start building. If any parts are
missing or damaged, refer to the manual's warranty section for replacement
instructions. If you can't positively identify an unfamiliar item on the basis of the
information given, set it aside until all other items are checked off. You may
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VEC-483K Owner’s Manual Voice Activated Tape Recorder Switch
then be able to identify it by process of elimination. Finally, your kit will go
together more smoothly if parts are organized by type and arranged by value
ahead of time. Use this inventory as an opportunity to sort and arrange parts so
you can identify and find them quickly.
""""
Qty Part Description Designation VEC P/N
#
2 1K resistor (brown-black-red) R3, R4 100-3100
#
2 10K resistor (brown-black-orange) R1, R2 100-4100
#
1 47K resistor (yellow-violet-orange) R6 100-4470
#
2 500K trimpot R7, R8 133-5500
#
3 1 uF electrolytic capacitor C1, C4, C5 270-4100-2
#
2 10 uF electrolytic capacitor C2, C3 270-5100-1
#
2 1N4148 diode D1, D2 300-4148
#
1 2N7000 plastic FET transistor Q1 305-7000
#
1 LM358 op-amp (8-pin) U1 324-0358
#
1 Microphone element, electret MIC1 410-1092
#
1 2P2T mini power switch SW1 504-2022
#
1 3.5mm stereo jack J1 601-5005
#
1 2.5mm mono jack J2 601-4009
#
1 9V battery snap BAT1 730-3005
#
1 8 pin IC socket for U1 625-0008
#
1 Plastic wire tie 745-2149
#
1 VEC-483 printed circuit board 861-VEC483
#
1 Owner’s Manual 925-VEC483K
PARTS PLACEMENT
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