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Four-channel
High-current
DC Fan and
Pump Motor
Controller – Part II
by
Nicholas Vinen
In the October 2018 issue, we revealed our new high-current fan and pump
controller, able to switch up to 40A total with a 12V nominal supply,
controlling up to four loads using the readings from between one and four
temperature sensors. And it’s programmed over USB, to make the many
different settings easy to control. In this second part, we cover PCB assembly,
wiring it all up and adjusting those settings to suit your installation.
O
ne of the main goals with this new DC Fan Controller was to provide many different options to suit
different situations, without making it a nightmare
to configure. We certainly couldn’t use jumpers and trimpots because there would be just too many and it would be
too hard to make any changes once the unit was mounted
in a vehicle.
So instead, we have made the unit configurable and
controllable over a USB text interface. Unfortunately, the
low-power micro we’ve chosen doesn’t have a great deal of
memory but we’ve come up with a way to provide a friendly user interface that allows you to see the exact settings
and make changes via a laptop or desktop PC.
Basically, you view and change your settings via a web page
which then produces a “magic string” of text which, when
pasted into the Fan Controller’s terminal, changes its behaviour to match up what you have entered on the web page.
So if you aren’t happy with the way your fans and/or
pumps are being operated, it’s a simple matter to reach
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Silicon Chip
the accessible USB plug or socket you’ve fitted, connect it
to your PC and upload a new configuration. You can even
test it without having to take the vehicle out on the road,
simulating battery voltage and changes and temperature
sensor changes to see what happens.
The PCB itself has been made reasonably compact to
make fitting it inside the vehicle easier, by using mostly
SMD parts. Despite this, it’s a bit larger than our last solo
Fan Controller (January 2018), so you’ll need a bigger box
and it’s a bit trickier to find somewhere to fit. But we did
find a good location in the packed engine bay of our test
vehicle and the wiring is pretty easy, once you’ve purchased appropriate connectors and gotten the hang of soldering them.
And anyway, it’s heaps more capable and configurable,
so the small penalty in size is well worth it.
PCB construction
The Fan Controller is built on a PCB coded 05108181,
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siliconchip.com.au
FAN1
FAN2
FAN CONTROLLER MK2 MODULE
1
OUTPUT 4
D3
FAN3
FAN4
221
D6
PTC1
10 F
1
1 F
CON3
22 F
10kΩ
CON5 - TS2
10kΩ
THERMISTORS
CON6 - TS3
18B20
CON7 - TS4
18B20
CON12
DISABLE
ON
OFF
TEMP
SENSORS
SC
20 1 9
Fig.4: this diagram shows where each part is fitted to the PCB and
also gives an example of how to wire the unit up. Most installations
will not use all of the connections shown. Be sure to get the supply and output polarities right – the positive leads go to the pads closest to the board edge. You can mix
and match the temperature sensor types; those shown here are just one possibility.
which measures 68 x 34.5mm. All the components are
mounted on the top side. Use the PCB overlay diagram,
Fig.4, as a guide during assembly.
If you are fitting onboard USB socket CON1, start with
that. Spread a thin smear of flux paste on its four mounting pads and five signal pins, then drop the socket on the
board and move it around until the two plastic posts on
the underside drop into the alignment holes. You should
find its five pins are then positioned over the pads.
Nudge it a little if necessary, to get the alignment perfect. Then apply solder to one of the four large pads which
attach its “feet”. You will need to apply a fair bit of heat
and some extra solder to get a good, solid joint. Re-check
the signal pin positions and if necessary, reheat that solder
joint and carefully nudge the part without lifting it up. It
may be hot, so use caution.
Once you’re happy with the position of the signal pins,
solder the other three mounting feet, then apply a small
amount of solder to those pins. If you load some solder
onto the tip of your iron and touch it to the end of the pin
(which is partially hidden under the body), the flux paste
you applied earlier should help to ‘suck’ the solder off the
iron and onto the pin and pad.
Repeat this for the other four signal pins and carefully
examine them under a magnifier with good light, to ensure
a good joint has formed and there are no bridges between
pins. If there are bridges, apply a little extra flux paste and
then use solder wick and heat from the iron to remove them.
Next, move onto microcontroller IC1. It is in a wide SOIC
package with relatively large pin spacings, so it is not difficult to solder. First, find its pin 1 dot and make sure that
it is orientated as shown in Fig.4. Also, check that it is sitting flat on the board, then tack solder one of its corner
pins. It’s easier to solder if you spread a small amount of
flux paste on all its pads first.
Make sure all the pins are correctly aligned on their pads.
If not, heat that initial solder joint and gently nudge it into
position. Repeat until you are happy that they are all lined
up, then solder the remaining pins and finally, add a little
extra solder to the first pin to refresh the joint. Inspect the
joints and as before, if you find any bridges, clean them up
with flux paste and solder wick.
Now you can proceed to solder IC2, IC3 and REG1 similarly, as they are all in smaller SOIC packages. Note though
that their pin 1 dot is orientated differently to IC1. Check
the orientation carefully against what is shown in Fig.4
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220Ω
REG2
100nF
CON4 - TS1
1S
1A FUSE
10kΩ
4.7kΩ 4.7kΩ 4.7kΩ 4.7kΩ
OUTPUT 3
1
CON2 ICSP
D4
Q2
GND D+ D- VCC
100kΩ
220Ω
POWER
TVS1
10-40A BLADE FUSE
1nF
12V
BATTERY
1kΩ
–
D1 100nF
IC3
+
470nF
1
1kΩ
100nF
1kΩ
D5
CON1
220Ω
1
39kΩ
Q4
OUTPUT 2
IC1
PIC 16F1459
IC2
Q1
CON13 - LED
D7
Q3
REG1
100nF
OUTPUT 1
10kΩ LED1
100kΩ
D2
The completed motor/pump controller is shown here
slightly oversize for clarity (actual PCB size is 68mm wide
– as seen above). Yes, it is all SMD components so a good
eye, a steady hand and a fine-tipped iron are all required.
before soldering each chip.
Mosfets Q1 and Q2 should be fitted next. These are in a
similar package to IC2, IC3 and REG1 except that the pairs
of pins on one side are joined together. So we have provided larger pads to solder those pairs of pins to the board.
Again, check that the pin 1 dot is orientated correctly –
the same as IC2 and IC3 – before soldering them in place.
These are seven small three-pin SOT-23 package pards
on the board: Q3, Q4, D5-D7 and REG2. They look similar
so don’t get them mixed up. Their pins are widely spaced,
so they are pretty easy to solder. Use the same technique as
with the ICs; it’s generally easier to tack the pin that’s all
by itself on one side first, then solder the other two pins
and refresh the first solder joint last.
Now fit the smaller (3216/1206-size) resistors and capacitors. The required values and positions are shown in Fig.4.
They are not polarised, so orientation is not important. The
resistors will be printed with a 3-digit or 4-digit code on
the top to indicate their value, while the ceramic capacitors will be unmarked so be careful not to mix them up.
It’s the same basic method – tack one end, check the
positioning and then solder the opposite side and go back
and refresh the first joint.
Besides making sure the parts are flat on the board and
that the solder joints are made properly, the main trick is
to be patient and wait several seconds between soldering
one side of the part and the other. This gives the joint time
to solidify. Otherwise, the part will tend to move out of position when you touch it with the iron.
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December 2018 85
You can now fit PTC1 and the large 220 resistor next to
it, using the same basic technique. Keep in mind that these
larger parts will require a bit more heat and solder to form
good joints. Neither of these components are polarised.
The diodes are also two-terminal devices and can be
soldered in the same manner as the passives but are larger
again so they will also need a bit more heat. Fit diodes D1D4 now, ensuring that their cathode stripe faces towards
the right side, ie, into the middle of the board. You can also
fit TVS1 now; it’s larger again but otherwise is similar to
the other diodes.
The last remaining SMD component is the 22µF tantalum capacitor next to REG1. It is also polarised and must
be soldered with its positive end (generally marked with
a stripe) towards the bottom edge of the board.
You can now move on to fit the headers that you require
for your application. You will need at least one of the four
temperature sensor headers (CON4-CON7); we recommend
that you fit all four, even if you aren’t planning to use them,
in case you want to add more sensors later.
You can also fit CON12 and/or CON13 now, for the enable/disable control and indicator LED. Again, you may
want to fit them even if you aren’t planning to use them,
Parts list – Fan/Pump Controller
for sample installation with one fan and three
temperature sensors (change to suit yours)
1 DC Fan/Pump Controller PCB Mk2, fully assembled
1 IP65-rated sealed high-temperature ABS box,
15x65x40mm [Jaycar Cat HB6122]
1 USB mini-B to type-A cable
2 30A waterproof blade fuse holders with LED
[Jaycar Cat SZ2042]
1 1A blade fuse [Jaycar Cat SF2126]
1 20A blade fuse [Jaycar Cat SF2138]
2 6mm non-insulated eye terminals [Jaycar Cat PT4934]
1 4-way Deutsch waterproof plug/socket set
[Jaycar Cat PP2149]
1 2-way Narva-style waterproof plug/socket set
[Jaycar Cat PP2110]
1 4-way Narva-style waterproof plug/socket set
[Jaycar Cat PP2114]
1 2-way 250-series automotive socket (to suit radiator fan)
Jaycar Cat PP2062]
1 1m length 2-core 7.5A automotive cable
[Jaycat Cat WH3057]
1 1m length 2-core 15A automotive cable
[Jaycar Cat WH3079]
1 1m length 2-core 25A tinned automotive cable
[Jaycar Cat WH3087]
1 1m length 25A black tinned automotive cable
[Jaycar Cat WH3082]
1 1.2m length 10mm diameter clear heatshrink tubing
[Jaycar Cat WH5555]
2 DS18B20 digital temperature sensors in waterproof
housings [SILICON CHIP cat SC3359]
1 10k lug-mount NTC thermistor [Altronics Cat R4112]
3 2-pin polarised headers, 2.54mm pitch, with pins [Jaycar
Cat HM3402]
2 M6 copper crinkle washers
2 M6 hex nuts
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Silicon Chip
in case you change your mind later.
Planning the wiring
As mentioned in the first article (October 2018), rather
than use connectors for the high-current wiring, we have
simply provided large pads on the board, to which fairly
thick wires can be soldered directly. While it is possible to
use fixed cables, we suggest that you use in-line connectors on most or all of the wires.
This has a few advantages: it makes testing easier, it
makes it easier to replace a sensor or fan later if you have
to, it makes it easier to remove the unit in case you need
to repair or reprogram the unit, and so on.
There are various suitable types of inline automotive
connectors, many of which are waterproof. While waterproof connectors are not critical for the 12V supply wiring
or connections to fans/pumps, we recommend that you use
them for the sensors, enable/disable line and external LED
wiring (if used) as water may conduct enough current to
affect the function of those devices.
See the panel below for more details on suitable connectors that are available.
Having decided where you will have connectors and what
type to use, you will then need to find a suitable location
for the case that will house your PCB. We strongly suggest that you use an IP65 (or better) rated waterproof box.
You could use an ordinary plastic box and waterproof
it with silicone but it will be hard to get it apart later if
you need to.
We used a sealed ABS plastic box from Jaycar – see the
additional parts list (at left) for details. Figure out where
your box will fit in the vehicle and also how you will attach it. We used a screw through one of the box’s two integral mounting holes, through a support member in the
vehicle (which already had a hole in it) and into a piece
of foam, capped off by a washer and a nut.
We also placed a thin piece of foam (with a hole in it)
between the box and the cross member. This provides
some vibration reduction compared to rigidly mounting
it to the vehicle.
Now that you have a location for the box, you can measure the lengths of all the required cables.
The easiest way to measure how long a cable needs to be
is to thread a spare piece of wire through the vehicle between the two points to be connected, loosely, then pinch
the end in one hand, pull it out and measure its length.
Remember that some parts of the car may flex or move, so
don’t make it too tight.
You will also need to calculate the minimum current
rating for each. This will typically be 10-20A for fan cables and 10-40A for the battery cables. Just about any wire
can be used for the sensor wiring, enable/disable switch,
LED and battery voltage sense wiring, as these all carry
mere milliamps.
When cutting the cables to length, remember to account
for the length lost stripping both the inner and (where present) outer layers of insulation, plus a bit extra in case you
damage the wire while stripping it and have to cut it off.
Having cut and stripped the insulation off the ends of all
the various cables required, crimp and/or solder the connectors on. Leave the connectors that will plug into the
PCB off for the moment.
Don’t forget to make provision for some heatshrink tub-
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There’s not a huge amount of space under the hood of many cars, especially a big V8! Choose a location that doesn’t
interfere with the operation of any other controls and, preferably, is easy to get to! Ensure all wiring is adequately secured.
ing for any multi-wire or multi-cable bundles, to keep everything neat when you run them later.
Configuration and testing
It’s a good idea to test the unit before making the final
connections since if you find any problems later, it will be
harder to fix them if the unit is already captive in its case
due to wires soldered directly to the board.
You will need to load it with its initial configuration. All
you need to do this is a computer with a USB port and a serial terminal program such as Tera Term Pro (a free download from https://ttssh2.osdn.jp/index.html.en).
You also need an internet connection, although it doesn’t
necessarily need to be available at the same time that the
computer is hooked up to the unit; you can prepare the
configuration beforehand.
Start by plugging the finished board into your computer
using either a Type-A to mini Type-B USB cable (if you fitted CON1) or a chassis-mounting Type-B socket wired into
CON3, plus a suitable cable.
Check that your computer has detected a new USB serial device. That verifies that the microcontroller is working
correctly. In Windows 10, you can do this by right-clicking
on the Start button, choosing “Settings” from the menu that
appears, then clicking on the Devices icon. You should see
a device listed with a name like “USB Serial Port (COM5)”.
The COM number will vary.
Open this serial port using your chosen terminal emulator and then type “status” and press Enter. You should
get a status display similar to that shown in Fig.6. If you
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don’t, check your port settings (the baud rate setting and
so on are not important).
If you can’t get any response, you may have a wiring or
hardware fault, so check that your USB socket is soldered
and wired correctly, that the PIC chip (IC1) is properly programmed and soldered and that all associated components
have been fitted correctly.
Once you’ve established communications with the chip,
open a web browser and go to http://siliconchip.com.au/
apps/DCFanMk2 This page will help you set up a basic
configuration for the unit, for further testing.
See the panel on Settings for help on how to set the unit
up initially. The web page referred to above translates your
desired settings into an encoded string which you can send
to the Fan/Pump controller, setting its configuration to the
desired state. Read up on the basic settings now – you can
ignore the more advanced settings for now.
You can read about them later, once you’ve established
that everything is working.
Loading the configuration
Once you have selected all the options you want, click
the “Copy to clipboard” button at the bottom of the window, then switch to your terminal program and paste the
configuration string (which is now in the system clipboard)
into the terminal. You can do this in Tera Term Pro by
right-clicking in the terminal window, then pressing Enter.
You should get a response that says “OK”. If it says “Error”, then the clipboard string has somehow become corrupted.
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December 2018 87
Explanation of Settings
Basic Settings
The settings user interface (available at
http://siliconchip.com.au/apps/DCFanMk2) is shown in Fig.5. Note that this has
been revised slightly since the October article, to remove some unnecessary features
and add some other useful ones. Start by
using the top four drop-downs to select
the type of temperature sensors you have
hooked up to CON4-CON7.
The following three voltage thresholds
control how the unit responds to changing
battery voltages. The defaults are sensible,
so you don’t necessarily need to change
them.
The first determines the voltage the battery needs to rise above before the unit will
become active.
The second determines the voltage it
must fall below when active to terminate normal operation and enter cool-down mode,
an optional time during which the fans and/
or pumps will continue to run, possibly with
reduced duty cycles.
The third voltage threshold prevents cooldown mode from flattening the battery. If
the battery voltage falls below this during
cool-down mode, the unit will immediately
go into sleep mode and wait for the battery
voltage to rise above the switch-on threshold before becoming active again.
The cool-down delay is designed so that
vehicles which charge the batteries sporadically will not enter cool-down straight away
when the battery is no longer being charged.
The battery voltage must be below the “Enter
cool-down” threshold for this long before it
will go into cool-down mode. For vehicles
which continuously charge the battery, set
this to a short time (eg, 1s).
The minimum cool-down on-time sets
the minimum time that the unit must be in
full operation before it goes into cool-down
mode. If the battery voltage is above the
threshold for a shorter time than this, the
unit will immediately shut down instead.
The cool-down time is the maximum
number of seconds that the unit will spend
in cool-down mode before shutting down.
Cool-down compensation allows you to
reduce the fan/pump duty cycles in cooldown mode, compared to what they would
be during normal operation given the sensor temperatures. Upon entering cool-down
mode, the duty cycles are immediately multiplied by the maximum value of this setting.
So if that is 75%, they will drop by 25%. The
minimum duty cycle setting for each output
will still be in effect.
As the battery voltage drops towards the
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shut-down threshold, the duty cycle multiply
value approaches the lower value of the setting. So with the default values, duty cycles
will reduce from 75% of nominal to 25% of
nominal before the unit shuts off completely.
Per-output settings
Each output has a similar configuration entry in the table beneath the global settings. You
can enable or disable each output individually
using the drop-downs at left. You can also set
output #2 to be a slave to #1 so that the two
outputs can be paralleled to give a single 20A
output. The same comment applies for outputs #3 and #4.
The PWM frequency must be the same for
outputs #1 and #2 and the range of possible
frequencies is shown on-screen, along with the
closest frequency to the one you have selected,
which will be the actual frequency used. Note
that the real frequency will also vary slightly
depending on the micro’s oscillator calibration.
The frequencies for outputs #3 and #4 can
be set independently but only if one of them
is 10Hz or less. The maximum frequency setting for these two inputs is 2kHz. Typically,
you would only use two different frequencies
if one of these outputs is controlling a pump
and you want it to be driven with long pulses.
In this case, you can choose a frequency as
low as 1/10Hz (100mHz).
The duty cycle for the output is determined
by three main parameters: the duty cycle range,
the temperature range and the way the sensor
data is combined. The lowest duty cycle in the
range given will occur when the sensor reading
is at the lowest temperature specified, and the
highest duty cycle will occur when the sensor
reading is at the highest temperature specified.
In other words, if you set the duty cycle
range to 40-60% and the temperature range
to 20-30°C, you will get a duty cycle of 40%
at 20°C, 42% at 21°C, ... 58% at 29°C and
60% at 30°C.
In the simplest case, this temperature is
derived from a single sensor. This is the default; you will find that initially, the duty cycle
of output 1 is derived from TS1, of output 2
from TS2 and so on. But you can change this
mapping. Multiple outputs can use the same
sensor if desired.
The final setting we’ll describe here is the
ramp rate, which specifies the minimum number of milliseconds that it takes for the output
duty cycle to change by 1%. So if you set this
to, say, 100ms then a change from 0% to 100%
duty cycle will take 10 seconds.
Advanced Settings
The Curve setting for each output allows you
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to compensate for loads where the speed/
power is not directly proportional to voltage, linearising their speed to temperature
relationship. For example, if you have a fan
where speed is proportional to the cube of
the average voltage across it, use the Cube
Root setting to provide a more linear speed
with temperature.
SVC stands for Supply Voltage Compensation and allows the duty cycle to be automatically dialled back as the battery voltage increases, providing a constant voltage/
speed for a given input temperature. Simply
specify the voltage at which you want this to
take effect (eg, 12V). If the supply voltage
is, say, 13V then the duty cycle will be reduced to 12/13 of nominal to give the same
average voltage across the load.
Advanced temperature formulas
To the right of the sensor name, you will
see a minus sign and then a drop-down box
containing zero.
You can select a different number to offset the sensor reading or, more usefully, you
can select a second temperature sensor to
make a differential reading. The temperature settings you enter for “Temperature
range” then refer to the difference between
the two sensors.
Rather than using a single sensor on either side of the minus sign, you can instead
change the blank dropdown in front of it to
read “min” or “max” and this will let you
select a second sensor.
The temperature used in the calculation
will then be the lowest (min) or highest
(max) of the two readings. Or you can make
one of the values a constant; the temperature sensor reading will then be clamped
when it goes below (min) or above (max)
that value. That feature is most useful in the
differential sensing mode.
So effectively, you can build a simple formula to derive the temperature reading from
up to four sensors, rather than just using
the temperature from one sensor directly.
There is one additional option; you can
actually have TWO such formulas, using the
same structure (but they can be different).
The unit will calculate both values and
then the result will be either the lowest (min),
highest (max) or average (avg) of the result.
That gives you a further way to combine
multiple temperature readings.
To enable that option, click on the first
black drop-down in the temperature measurement box and change it to one of the three
other options. The second formula will then
appear, and you can fill it in.
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Immediately after pressing Enter, the new configuration
takes effect. Type “show status” and press Enter and you
may see some changes already.
Initial testing
You can now use the “override” command to perform
some basic checks on your settings. The override command
lets you ask the unit to pretend that the supply voltage or
temperature sensor readings are a particular value, so you
can see what happens without actually having to vary the
supply voltage or heat up or cool down the sensors.
This is useful both when the unit is installed in the vehicle (since you can’t always get the sensors to read what
you want while idling) but also at this early stage, to avoid
the need for variable voltage sources and variable resistors.
First, run the “status” command (type “status” and press
Enter). Since the unit has no 12V supply, it should give a
supply reading close to 0V and it should indicate that it is
in sleep mode as a result. Now issue the command “override supply 14.4V” (or similar). Re-run the status command.
You should see that the supposed supply voltage has increased and that the unit is now in run mode.
However, since it knows there is no 12V supply, it will
not drive the Mosfets, to protect the driving circuitry (which
runs off the currently non-existent 12V supply).
Still, you can see what PWM duty cycle the unit will
drive each output to for the current temperature sensor
inputs. You can then issue a command like “override TS1
47.5C” to make it pretend that temperature sensor #1 is actually at 47.5°C, rather than its actual current temperature.
Re-run the status command and observe how the output
duty cycle(s) change.
You can then override other sensor temperatures, or
change the existing one, to see what happens. If it isn’t
working as expected, review your configuration and repeat
the procedure above to load the new configuration into the
unit, then continue testing in this manner. See Fig.6 for an
example where the override feature is used.
Once you have finished testing, issue the “override clear”
command and the unit will go back to working as usual.
You can then proceed to connect actual loads if you
want – they don’t have to be fans, a 12V LED would work
and would give you an easy way to see how the duty cycle changes.
Having said that, since your fan(s) will already have the
right connectors, it may be easiest to use them for testing.
Just make sure you have them in a safe location so that
when they are powered up, they don’t fall over and the
Fig.5: a screen grab of the latest version of the web-based configuration interface. The upper section allows you to
configure the temperature sensor types, supply voltage thresholds, timing parameters and cool-down mode settings. The
lower section controls the relationship between sensor temperature and duty cycle for the four outputs. In this example,
outputs #1 & #2 are combined to control a single 20A fan, based on the temperature of three sensors.
siliconchip.com.au
Australia’s electronics magazine
December 2018 89
Common automotive connectors
Deutsch connectors
We have used two different types of waterproof connector on our
prototype. For the two DS18B20 sensors, we used a single 4-pin
Deutsch plug and socket set (Jaycar Cat PP2149). This was cheaper
than two 2-pin plugs and sockets (Jaycar Cat PP2150). A 6-pin version is also available (Cat PP2148).
Deutsch connectors are used widely on vehicles and are known to
be reliable, with a typical current rating of 13A/pin. They are relatively
easy to put together, although there are a few steps, and ideally, you
should use a specialised crimping tool (but you can get away without
it). Jaycar sells an appropriate tool, Cat TH2000, which also requires
a Deutch die set (Cat TH2011).
First, if the wires you will be attaching to the connectors are part
of a multi-core cable, you will need to strip back about 20mm of the
outer insulation to expose enough wire to feed into the connectors.
You need to strip about 3mm of insulation away from the end of
each wire to crimp into the pins later.
Both the plug and socket have a thick gasket inserted into the rear,
with a small hole for each wire. The first step is to carefully prise this
out of each shell and then push wires through these holes. If your
wire is particularly thin (as is the case with the waterproof DS18B20
sensors), use heatshrink tubing to make the wire diameter larger so
it will seal properly when pushed through.
The next step is to crimp the wires onto the pins. One set has
pointed ends and the other set have cups in the end, which accept
the pointed ends of the other pins. The cupped pins are larger so you
can figure out which shell they go into by checking for the one with
the slightly larger holes.
Once you’ve figured out which pins will go on which wires, fold the
larger metal leaves around the wire insulation, crimping them to hold
the wire in place. Next, fold the smaller leaves around the exposed
copper. A Deutsch crimping tool will do all this in one step but if you
don’t have one, you can use small pliers (ideally with angled ends)
to carefully fold the leaves around the wire and clamp it down hard.
It isn’t ideal but it works.
The trick to doing this is to make sure that you don’t just squish
the leaves flat, as they will tend to spread out and make the pin too
wide. You also need to compress them horizontally, so that the final
crimp is compact.
We also like to add a little flux and then solder to the top of the
exposed wires to ensure good electrical contact, but that technically
shouldn’t be necessary if the wires have been properly crimped (but
that’s quite tricky to get right if the wire is very thin).
Once all the pins are soldered, push them into the rear of each
housing until you hear them click into place. For the cupped pins, you
will know they have been pushed home because their ends will be flush
with the front of the connector.
For the pointy pins, it can be quite hard to push them in (especially
with the gasket in the way), so you may find it easier to push them in
part way and then grab them from inside the front of the shell using pliers, and pull them forward until they lock in place.
Now all you need to do is push both gaskets back into the rear of each
shell, making sure that they sit flush with the rear of the connector all
around the edge, then push the flat orange plastic piece into the end of
the socket (ie, the shell with the cupped pins) until it locks into place.
This stops the sealing gasket from being pulled off when you withdraw
it from the plug later.
The green plastic wedge pushes into the end of the plug and locks in
place in a similar manner.
Narva connectors
This is another type of multi-pin waterproof automotive connector, rated
at 20A/pin. They are a bit more expensive than a Deutsch connector but
have a higher current rating. Jaycar sells these in 2-pin (Cat PP2110),
3-pin (Cat PP2112), 4-pin (Cat PP2114) and 6-pin (Cat PP2116) versions.
We have used two in our set-up; one 2-pin version for the NTC thermistor on the intercooler radiator, mainly because we already had a suitable plug wired to the existing thermistor in the vehicle, and a 4-pin version to connect the unit to the battery.
Its 20A rating is sufficient for our installation as only one fan is being driven, and the four pins mean we can connect both pairs of battery
wires in a single plug/socket.
One of the disadvantages of this type of connector is that the socket
pins are a bit sloppy and so plugging the two pieces together can be a
bit of a chore. But once the pins find the cups, they all lock into place.
Assembling these is similar to the Deutsch connectors but there are
some differences. Rather than one large rubber gasket at the rear, there
are individual gaskets for each wire, so you need to remember to push
these over the wires before crimping the pins (although they can be
pushed over the pins if you’ve forgotten).
Both the plug and the socket have a section at the rear which unclips
and swings out, to allow you to insert the pins, which click into place.
You then push the gaskets in, leaving the small central section sticking
out, then swing the rear back into place and latch it using the plastic
clips. This prevents the gaskets from falling out.
You can tell which is the plug and which is the socket since the socket
(which takes the cupped pins) has larger entry holes and is overall deeper.
Note that the gaskets will fit wire rated at around 15-20A. Thinner
Both the Deutsch (left) and Narva (right) connectors
are waterproof and are available with various
numbers of pins, from 2 to 47(!).
90
Silicon Chip
Australia’s electronics magazine
siliconchip.com.au
gauge wire will need to have heatshrink added to form a proper seal
while larger gauge wire (~25A) cannot fit through the gaskets (and
will only just fit in the connector). You will need to use silicone sealant if you need connectors with heavy duty wiring to be waterproof.
Overall, we suggest that you stick with Deutsch connectors unless your application exceeds their 13A/pin current rating as they are
easier to use.
Non-waterproof options
Chances are your fans/pumps will already have a plug and it will be
easier if you can find a matching plug rather than cut off the existing one
and attach a new one or hard-wire it (although that’s certainly feasible).
Our fan already had a “250-series” two-pin connector and these
are available from Jaycar too; they sell 2-pin (Cat PP2062), 3-pin (Cat
PP2064), 4-pin (Cat PP2066), 6-pin (Cat PP2068) and 8-pin (Cat
PP2069) versions.
Make sure you use wire with a high enough current rating to suit
your fan. Keep in mind the fan’s specified nominal current may be for
a 12V supply, and it could draw around 30% more current at 14.4V
when the battery is being charged.
Another option for high-current connections, especially to the battery, is Andersen connectors, which are also available from Jaycar.
These are available in a range of current ratings including 35A, 50A,
75A, 120A, and175A. These are dual “genderless” connectors (ie, two
identical connectors will plug into each other).
Individual Anderson connectors are also available, with lower current ratings.
The 50A connectors are quite large but are probably the
best choice for battery connections requiring 30-40A. The lower rated connectors will not accept thick wire and are challenging to assemble, whereas the 50A and up versions feature a “solder cup” which you can fill with liquid solder and then push the
wire into, making them relatively straightforward to put together.
We used the
250-series (right)
plug because that’s
what our radiator
had fitted. The
two-way Narva
connector (below)
was used because
it had a higher
current rating
(20A). There are
several other types
available.
siliconchip.com.au
spinning blades won’t hit anything.
You will also need to connect the sensors (if not already
connected) and a 12V power supply with sufficient current
capability for further testing. This could be your car battery. You can also use the override command in live testing.
It’s also a good idea to check that the sensors are actually
working, rather than just relying on the override command.
Test each sensor by heating it up or cooling it down slightly, then re-run the status command and check that the temperature reading from that sensor has changed as expected.
You can use a hot air gun, some ice, a cigarette lighter
etc. Just make sure if you are heating the sensor that you
don’t overheat it or anything nearby.
For example, if using a lighter, keep the flame some distance below the sensor and don’t heat it for more than a
few seconds.
You may also be able to observe the fans/pumps being
driven, depending on whether you’re pushing the sensor
temperatures into the ranges where those loads are activated.
Preparing the case
Now you need to figure out where each wire is going to
enter the case. Try to keep in mind the layout of the pads
and connectors on the PCB, ie, avoid wires crossing all
over the place inside the box, if possible. Mark and drill
the holes required to get those wires into the case. Don’t
make the holes any larger than necessary.
Solder the fan/pump and power supply wires onto the
pads, in the locations shown on Fig.4. It helps to pull these
as far into the box as necessary, so you can do the soldering outside the box, then pull the wires back out when
you have finished.
The other connections are made with polarised plugs.
Depending on the sizes of the holes you’ve made, you may
be able to crimp/solder these onto the wires and then feed
them through the holes, then push them into the plastic
plug blocks. If they don’t fit through the holes, you will
have to feed the wires through first and then crimp/solder
the pins afterwards.
Note that the LED and any DS18B20 temperature sensor
wires are polarity sensitive, so make sure you refer to Fig.4,
so you get them on the right side of each plug. The enable/
disable and any NTC thermistor wiring is not polarity sensitive so the pins can go into the plugs either way around.
While it isn’t necessary to bring the USB connector outside the case – you could just open up the case and plug
in a cable if you need to change the way the unit operates
– it’s certainly more convenient to have it available from
the outside.
This is especially true if the unit is going to be buried
behind panels or under other bits of the vehicle.
We’ve provided the option to fit a waterproof USB socket on the outside of the case and connect it via pin header
CON3. Simply wire up the USB socket pins as per Fig.4 –
the standard USB wire colour codes are shown there too.
But in many cases, it will be easier to feed a micro-B to
Type A USB cable through a hole in the box and plug it
into CON1 on the board, then seal up the hole with silicone sealant.
Tuck the USB plug away somewhere that it won’t get
splashed with too much water and tie it up with a twist
tie or two so that you can easily remove it and plug it into
Australia’s electronics magazine
December 2018 91
List of USB serial terminal commands
status - shows the unit’s current status, including sensed
battery voltage, sleep/cool-down/active state, sensor
temperatures, PWM output duty cycles and override
status.
Fig.6: this shows how you can use the override command
in the USB serial terminal to test the unit. You can set
pretend supply voltages and sensor temperatures and
observe how this changes the output duty cycles. If you
have fans and a power supply connected, their speeds will
change as if the sensor temperatures have changed to the
values given.
a laptop later if you need to reconfigure the unit.
dump - displays the unit’s configuration string (including
restore command) on the console. This can be pasted
into the web app to retrieve the current configuration.
restore - when followed by a base64-encoded string of the
appropriate length, updates the unit’s configuration in
RAM with the new settings (get this from the web app).
save - saves the current configuration in RAM to flash,
so it is retained the next time power is cycled. Usually
used after a restore command.
That’s the approach we took in our installation
revert - loads the configuration from flash into RAM,
overwriting any changes which have been made but
Once you have fed all the wires in through the holes
not saved since power-up.
you’ve made in the box, solder and/or plug them into the
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con$20.00 inc P&P & GST ORDER NOW AT www.siliconchi p.com.au/shop $10.00 inc P&P & GST
You can then locate it in your vehicle, in the place de- venient, out of the way but where you can easily reach it
termined earlier, and tie it down using screws, cable ties once any panels are back in place that you have removed,
or any other method you see fit.
in case you need to adjust the settings later.
As we said, it’s a good idea to place some springy foam
Now all that’s left is to go for a drive and make sure that
or rubber between the case and the vehicle to provide some everything is working as expected! If you want to leave a
vibration isolation. We used one of the case’s two water- laptop plugged in while driving (eg, via a USB extension
proof screw mounting holes to attach it to a cross member cable), that’s OK, just make sure it’s routed in a safe manin the vehicle.
ner (ie, don’t leave the bonnet open while driving) and get
After another quick check to make sure everything is a passenger to monitor the sensors and fans via the “staworking, screw the lid on (including the waterproof gasket) tus” command.
SC
The S
C
READY RECKONER
It’s ESSENTIAL For ANYONE in ELECTRONICS
The SILICON CHIP READY RECKONER
Gives you instant calculation of
Inductance - Reactance - Capacitance - Frequency
It’s ESSENTIAL For ANYONE in ELECTRONICS
You’ll find this wall chart as handy as your multimeter – and just as useful!
Whether you’re a raw beginner or a PhD rocket scientist . . . if you’re building, repairing, checking or designing
electronics circuits, this is what you’ve been waiting for! Why try to remember formulas when this chart will
give you the answers you seek in seconds . . . easily! Read the feature in the Januar y 2016 issue of SILICON CHIP
(you can view it online) to see just how much simpler it will make your life!
All you do is follow the lines for the known values . . . and read the unknown value off the intersecting axis.
It really is that easy – and fast (much faster than reaching for your calculator!
Printed on heavy (200gsm) photo paper Mailed flat (rolled in tube) or folded Limited quantity available
Mailed Folded:
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92
Silicon Chip
Australia’s electronics magazine
HU
420x59G4Em
on heavy
photo pa
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siliconchip.com.au
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