*see below for new files added*
Illustration revised, please check new info 10/12/02
Cases for the
Tach-Plus
Pac-Tec K-HP-9VB
RS 270-0213 (this
is a new RS #)
Mouser 616-62006 (bone)
616-60620 (Black)
Buttons for
the Tach-Plus switches
Mouser # 611-PEBLK , 611-PERED, 611PEGRY, 611PEWHT
(These are square caps. The last three letters indicate
the switch color)
611-PVBLK, 611PVRED, 611PEGRY, 611PEWHT
(These are round caps. )
We do not include buttons with kit because of the
many cap variations and due to the fact that many
builders like to individualize their cases or build the
Tach-Plus into a specialized machine.
***if any builders have Tach-Plus
kits and want extra sensors to run remotely, send me
an email and I'll see you get a
pair to experiment with.***
Thank you for all your responses
praising the quality and ease of the kit. I know a lot
of you are waiting for the remote
sensor so I will try to get it out as soon as things
slow down.
The Tach-Plus
is a digital readout IR (infra-red) tachometer and turns counter.
It is featured
in the September 2002 issue of 'Poptronics' as a construction article.
Because it uses a programmed microchip
the circuit is simpler and more versatile than
devices built with discrete components.
Those of you
who build your own boards will find that we have made the circuit
board so that it is easy to fabricate.
The traces are extra thick (.030 "), no traces run
between IC pins and all but two
vias are placed on components. The Tach-Plus board
we sell is of the highest quality
with thick traces, plated through holes, solder mask
and a silk screen component layout.
Our microchips
are tested after programming and packed in static safe bags.
Power to the
circuit can be from a 9 volt battery, a string of cells or through the
wall jack which will take any voltage
from 9 to 15 volts AC or DC with no polarity
orientation required.
There are no
pots or critical electronic adjustments to make. All that is required
is careful alignment of the emitting
diode itself. While the instrument can be used
without a case one will keep the
stray light rays from interfering with accurate
readings. Although a specific Radio
Shack case was used here the Tach-plus can
be built in any case you might desire,
especially for long term portable use where
a group of more desirable series
AA to D cells can replace the small 9 volt battery.
The etched, drilled and silk-screened
PC board is designed to fit into
a Radio
shack case # 270-0213.(old #270-213)
(Two boards are shown one top and
one bottom view) See the components
page for boards and chips. If you
have
trouble finding the case. The same
part
is available from Mouser #616-62006
The completed circuit board inside
the
Radio Shack case. Notice the only
'danglers' (wires from the board)
are to
the 9 volt battery compartment which
is accessed from the rear of the
case.
Because this
instrument requires a programmed chip and detailed
soldering we advise that good soldering
skills are necessary by those of
you purchasing the kit.
The building time, with all components
on hand, is between 2 and
4 hours. Please don't rush. Take
your time and enjoy it!
Those of you
who have built the project from the 'Poptronics' article
should note that we now advise cutting
a 1/2 inch hole in front of the
sensor so that it is not obstructed
by the clear front plastic. The
only purpose for the clear plastic
is to keep the emitter diode stationary
and to protect the circuit from debris.
Don't drill the 1/2 inch hole
through the clear plastic, in front
of the sensor if you intend to use
the Tach-Plus in harsh or wet environments
where there is a chance
of debris entering the case.
Notes:
1. Diodes D1 and D2 have their positive
lead connected to the square
terminal on the circuit board.
2. If you have downloaded the
software from the "Poptronics" web
site check to see if rpm readings
under 100 are in the form of 00.0.
( example 56.4 rpms). If not then
download the latest software here.
3. If you are using a 'perf' circuit
board then try to follow as closely
as possible, the layout of the finished
PCB to keep noise to a minimum.
4. Please use a dip socket for
U2, the microcontroller. We will not
accept any returns for chips that
have been soldered in.
5. Please see the components page for chips, boards and sensors.
6. Change R3 to 1k from 100 ohms.
7. If you have a kit with two
470 uF caps. at 10 volts you can change
C 7 to 100 uF at 25 volts to allow
using a higher than 6 volt wall
transformer.
Text
Tach-Plus Schematic
llustrations