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A few handy tools for electrical
BENCH TOP PROJECTS
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This page contains several tools I have found
useful over the years in developing various projects. Like modeling, some are purchased
“ready-to-run”, some are like “kit-bashing”, while others are more like
“scratch building.” Please send me a line if you find anything
useful or have any questions. E-MAIL
HERE
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Almost any project of any size is easier when
prototyping with breadboards to test new circuits. These come in many versions and are
readily available. This breadboard
has interlocking lugs along the side such that any number of breadboards
can be joined together for prototyping larger circuits.
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Sometimes the breadboard is nested or mounted on
a base like this electronics project trainer. It has circuitry such as a power supply, switches,
and some on some sort of display.
This old standby contains a power supply with on/off switch, a bread
board, a square wave generator, four LEDs, Two switches and of course a bread-boarding
area. Unfortunately, it is no longer
available but other devices like it are.
Note that this type of hole pattern is available both with
solderless connections and separately on a PC board where the connections
must be soldered. There are also a
number of prototyping boards for any need.
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Many circuits can be broken down into common
building blocks. One way to avoid
the repetitive task is to build small building blocks to go with the
prototyping board. The small power
supply in the upper left has a LED to show when power is on and provides
five volts DC at about 1/10 amp.
The module at the upper right is simply a beeper
that is turned on or off by either the switch or a signal.
The small transformer is typical of many small
projects and the fuse is for larger circuits that may need protection.
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Some projects may require a set of pushbuttons,
switches or other controls. This
shows a more complex sub-circuit used to develop a sound system and
contains a power supply for the entire project. The controls represent a simulated
computer interface. This board will
not be part of the finished project.
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MULTI-METERS ARE A MUST
FOR DEVELOPING AND TESTING PROJECTS.
TYPE a is a rugged, reasonable priced meter from DigiKey.
A good digital multimeter is generally more
rugged and mobile.
Meters are an important tool and I use several. Most meters will measure resistance, voltage (AC and
DC) and usually current (Also AC and DC).
There should be fuses to protect the meter against excessive
current. This model stores spares
inside for convenience. This model
also measures capacitance while others can also measure inductance as well
as the integrity of diodes and transistors.
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An old-fashioned analog multi-meter can “see”
fluctuations and spikes that a digital meter ignores. It also is easier to interpret any
fluctuating measurements. This
40-year-old meter still works and sees occasional use. It can measure house current up to 30
amps and is more accurate then most smaller meters.
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This simple but extremely rugged meter was part
of a build-it-yourself color television kit. The television has long since been
replaced but this meter still sees frequent use. It has a very limited range of voltage or
resistance but that is all that is required to find shorts in Trackwork or
a quick check on some simple project
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There are several panel meters available
including this digital version.
While these types are typically sold as voltage or Ammeters, A
voltmeter CAN be used to measure amps
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This meter kit is not quite as fast or accurate
as a commercial grade meter but is extremely versatile. The PC board is designed so that it can
be cut in half below the display and folded for tight configurations. There are two versions of this display
used in hundreds of meter designs, One for mounting as shown and One for
mounting on the other side of the PCB.
The meter also has a breadboard area and instructions to show how
the same meter can measure volts OR amps and even resistence in almost any
range with the decimal point properly placed
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Note the double row of holes in the picture to
the left in the middle of the board.
This is where the board can be cut and reconfigured as shown
below.
Two of these meters are used in the Bench-top
power supply shown below in a wooden case.
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This third dual-meter combination is one of
several series of standard panels meter meant for instrumentation such as
the volts and amps of track power.
Some of the less expensive of this series costs less then the older
mechanical meters. It is more rugged
and less prone to damage due to wiring errors.
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Sometimes it is handy to have a way to inject
some sort of signal at one end of a circuit to see what happens at the
other. Both of these generators use about the same parts And form sign,
square and triangular waves Ranging from one wave every ten seconds To
100,000 waves per second.
This particular generator is a kit that can be
run from an internal batter or external
power.
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This generator was built from spare parts, it is
designed to run from 9 to 18v AC or DC and can supply five volts to a
project under development. The
jumpers to the extreme right control the frequency, the LED flashes to show
the power is on. The header at the
bottom delivers all three waveforms simultaneously. This device is not elegant but it works
quite nicely and takes almost no room on a desk top.
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This dual channel occiliscope
doesn’t see much use but it can be handy for more advanced projects or just
to satisfy curiosity. It is the most
sensitve way to find glitches and fluctuations of voltage.
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List of kit vendors for these and
many other electronic devices
CanKits
Elenco
Jameco
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A test track can be
bulky and occupy precious desktop space when testing electrical circuits
A simple motor can
simulate the characteristics of an engine.
This unit was used to test
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A test track
is a must-have when it comes to engines. The most obvious reason is for testing an
engine mechanically after lubrication or replacements of parts. It is also needed for cleaning wheels
after running on dirty track and testing any electronics such as DCC
decoders. It also comes in handy for
running in new engines.
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Over the course of years I have grown tired of
building a power supply for each project.
Eventually I got smart and built a number of modules that can be
re-used for every new project. This
is a simple 5v power supply for prototyping small projects. The on-board regulator is good for only
1/10 of an amp and then only for short periods. Adding a heat sink to the regulator would
allow surges to 1/5 amp or 1/10 amp continuous. This is more than enough to power 5-10
typical integrated circuits
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This 35 volt 5 amp switching regulator was
designed to work with capacitor-discharge switch machine control. The switching regulator is a bit more
complex and requires the large donut-shaped inductor to work but it is
highly efficient.
I chose to wind my own transformers which is not
that difficult and yields the ultimate power. A single turn can effect the output but a
small potentiometer makes peak performance a cinch.
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The heavy-duty 10-volt supply shown here is used
for larger projects that already have part of their own power supply. I am a firm believer in safety and keep
all transforms contained in a separate fire-proofed cage on the layout and
well-insulated on the work bench.
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This little gem is actually little more than a
glorified power pack. I use it to power up many projects as well
as to power a test track when working with locomotives.
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This is a handy little desktop I use with many
projects. Each section is separate
from the others so like the above prototyping board, a wide variety of
power supply configurations are possible including either an internal or
external transformer, full wave or half wave rectifier, a pushbutton for
“smoke” testing new circuits and a switch to turn a circuit on or off. It also contains a Voltmeter, Amp meter,
three separate voltage supplies, and a battery charger For nine-volt
batteries. The external AC sockets are
on their own switch. In short, every
thing you need to power and test a circuit under development
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About Batteries
Notes on batteries
Battery vs. cell
Non-chargable
Carbon zinc
Alkaline
coin
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Chargeable
Lead/acid
lilthium
NiCad
NiMH
Recharge at capacity for two hours
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Rechargeable batteries a bit less than non
rechargeable
Rule of thumb is to charge at capacity rating for
two hours
i.e. a 9v
175ma hour battery is charged at 175 ma for two hours
stop if battery gets warm
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A new or fully charged battery supplies certain
voltage
This voltage drops
With load
As battery discharges
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This charger is designed
to charge up to six batteries at once.
Switch selects which battery to monitor
(or none)
Charges 9v 175 ma battery in about four hours
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First is testing devices
Powered by batteries it is
checking
No display, batteries are
dead
Otherwise it will indicate
battery charge
Normal charge is between
seven and eight volts
This is a much simpler
monitor
Uses batteries
Normal charge is about eight volts
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Model Railroading is fun in Connecticut.
Bob Van Cleef, MMR
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