DISCLAIMER
! Note:
Anything you do to your camera is of your own volition. Don't come running
to me if you ruin a lens / filter / camera etc.
| This is for those not quite familiar with
the electronics 'speak' mentioned in this project. |
| Tin (tinning) |
To give a light coating of solder. |
| Beer |
Something to give to the person you've got
helping you out on this. |
| +ve |
Positive |
| -ve |
Negative |
| Breaking the track |
Using a drill bit to remove a portion of
copper track at a specified hole so there is no copper linked across
the hole |
| Solder bridge |
Quick way of joining two (or more) tracks
by means of a blob of solder |
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Following on from Part I of the portable power pack project, we're going
to be looking at the construction of the battery monitor circuitry. This
part of the project is useful as a stand alone battery monitor and can
be built just for testing such batteries as the Fuji NP-80 batteries (for
the Fuji 4900z / 6900z) before setting off on a photo session.
This part involves more complex soldering and electronics skills, so
if you're new to this and still want to complete this part, I'd get a
friend who's into electronics to help advise and help you build it.
A common problem for the Fuji cams is the battery warning display. When
the battery power is low in the camera, it displays the usual red battery
symbol, but this only gives a few seconds (minimum) to let you continue
shooting. This is clearly inadequate and so this project part should help
give a more accurate view of the state of the batteries, with enough "low
power" warning time. This is accomplished with 5 LEDs - 3 OK (green),
1 Warning (yellow) and 1 Alert (red). At the yellow stage, you should
be looking at changing your batteries shortly after reaching this stage.
The project was built on Veroboard (copper strip board) but if you're
into etching your own copper PCBs, I'm sure you can come up with a suitable
design.
The more technically competent may want to cut to the chase and see the
circuit diagram
used for this project.
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1. Gather together your parts.
Cut out a piece of Veroboard that gives you a minimum of 21 holes
along the copper strips, and 11 complete rows of copper strips.
Using a piece of paper, trace around the Veroboard and mark each
hole across (left to right) with a letter (a to u) and down numbers
1 to 11 as shown in the diagram across. We'll call this piece of
paper our "hole locator" paper from now on.
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Copper strips run horizontally on this diagram
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2. Break the track at the following hole locations:
Turn the copper strip side upwards, and use your "hole locator"
paper to locate and break the track at the following locations:
b2 down to b10 (inclusive), g2 down to g10 (inclusive), f1, i8,
l5, o4, p1, p5.
You should end up with your copper strip being broken as shown
in the following diagram.
NOTE: This is the only time you will use the "hole
locator" paper with the Veroboard copper strip side facing
upwards. Remaining hole locations will be given as though you're
looking down onto the plain side of the Veroboard.
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Yellow circles mark areas of track breakage.
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3. Turn the Veroboard plain side up again and place the
IC socket so the upper left pin is in hole n2 and the lower right
pin is in hole q10. Solder in place. Don't be tempted to insert
the IC into the IC socket yet - there's more soldering to do and
you don't want to fry the chip by accident.
Now solder the 3 wires between the following holes: k1 to k4, k5
to k8 and j3 to j9 as shown in the diagram across.
Note: When soldering my board, I used a bigger board and cut it
down when completed - the photo across is therefore a guide only
for positioning the components.
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4. Now solder in the capacitor between holes l3 and m4 (yes
it's diagonally positioned.
Next solder in the 1K resistor between holes m6 and m9.
Then solder in the 10K resistor between holes l7 and l9 (you may
have to put the resistor on a slight slant for this).
Trim the component legs as appropriate.
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5. Next, insert the two miniature potentiometers into the
holes as shown in the diagram opposite.
P1 (the 22k potentiometer) should be fitted into holes e5 (middle
pin of pot), i4 and i6.
P2 (the 10k potentiometer) should be fitted into holes a8 (middle
pin of pot), e7 and e9.
Trim the component legs as appropriate.
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6. Now we have to connect the LEDs. Because these are diodes
(only allow electric current to flow through them in one direction),
they have to be connected the right way round.
An LED's polarity can be determined by looking at the length of
its leads. The longer of the two is the +ve anode. If your leads
are the same length, you can still tell which is the anode and cathode
by looking at the side of the LED's plastic casing - the fatter
metal bit inside is the cathode. The diagram opposite should make
things clearer...
Solder the LEDs in the following holes:
| LED Colour |
Cathode Hole |
Anode Hole |
| Red |
s2 |
u2 |
| Yellow |
s4 |
u4 |
| Green |
s6 |
u6 |
| Green |
s8 |
u8 |
| Green |
s10 |
u10 |
Trim the component legs as appropriate.
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7. Now turning the board over so the tracks are face up,
and making sure your track breaks are in the positions shown in
the diagram on your hole locator, create solder bridges across the
following holes:
a1 to a11 inclusive, h7 to h8, h10 to h11, q5 to q6.
This diagram only shows the grey solder bridges. By this time you'll
have a myriad of solder joints on your tracks.
Don't apply the heat for too long on the big solder bridge as your
LED anodes are connected to this and you may burn out the LEDs.
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8. Connect your switch across holes e1 and g1.
Connect a red piece of wire (colour chosen to represent the +ve
pole of the battery) to hole b1 and a black piece of wire to hole
g9.
My photo here shows the red and black wires in different holes
- ignore the photo and just go with the diagram above it for location
of wires.
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9. Finally place your IC chip into the socket holder so
that the notched end of its casing is resting on row 2. Press it
in firmly, but don't bend the pins in the process !!!!
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10. At this point you can decide either to use this project
part as a stand alone battery checker and use it for say:
Option 1 - checking the voltage of an NP-80 battery as shown
in top diagram here...
If you have chosen this, Go to step 11 for calibration.
Option 2 - you may want to use it for testing 4 AA batteries
(s602Z owners), in which case you may want to get hold of a 4xAA
cell battery holder as shown opposite...
In this case, solder a PP3 battery clip to your circuit board in
the holes described in section 8 above, removing the existing wires.
The wires should be replaced red for red, black for black so that
the polarity to the circuit remains the same.
Use the PP3 clip to connect to the battery holder using the clips
on the holder.
If you have chosen this, Go to step 11 for calibration.
Option 3 - You may want to connect it to your the power
pack you built in Part I of this project. In this case, cut the
PP3 clip off your DC plug adaptor at the soldered join in the wires.
Re-tin the wires attached to the DC plug and also those on the PP3
clip.
Solder the PP3 clip with the red and black holes as described in
section 8.
Now solder the wire that leads to the central hole of the DC Plug
to hole a1. Solder the wire that leads to the outer ground connection
of the DC plug to hole a9.
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11. Calibration Time
Whichever battery testing option you have chosen, you need to now
adjust the potentiometers to make sure that the LEDs light up correctly
for a "full" power pack and an "empty" power
pack.
Turn all the potentiometers fully clockwise using a watchmaker's
flat blade screwdriver.
Connect the chosen "fully charged" battery making
sure that the +ve and -ve poles of the battery are attached correctly
(attaching the battery the wrong way around will possibly destroy
your IC chip so be careful). Keep the switch pressed down at this
point.
Slowly turn the potentiometer P1 until all the LED are just lit
(they will glow from red to green).
At this point you've set your battery monitor to tell you that
the attached battery is fully charged (all the LEDs are lit).
Now go and use up your battery until the camera shows you've
got a red battery warning.
Connect up the battery again to your monitor circuit and adjust
potentiometer P2 anticlockwise until only the red LED is lit.
At this point, you've set the lower voltage for your monitor and
it's ready for use in anger.
As you use your battery up, you may want to see the effect it has
on the LEDs, you'll see the remaining lit LEDs go down through the
3 green , 1 yellow to the "alert" red.
Before setting off on a trip, it's always useful to check your
batteries status the night before and charge as appropriate.
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Turn P1 anti-clockwise until all your LEDs glow...
Turn P2 until only the red LED is glowing ...
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Next Time ... Enclosure
The next step is to enclose your circuit in a nice box so it doesn't
get damaged with everyday handling.
In the final part of this project we'll look at enclosing this
circuit, together with the power pack from Part 1 into a neat belt
harness so it's fully portable and doesn't get in the way.
As always: If you're not 100% certain about your technical ability
to complete this project, get a friend to help. But remember to
say "thank you" :)
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