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Xmas projects & soldering SMDs
It’s good to see another round of
Xmas Ornaments from Tim Blythman
(November 2020; siliconchip.com.au/
Article/14636). Tim has successfully
introduced me to working with SMT
devices with the tiny Xmas Tree last
year (November 2019; siliconchip.
com.au/Article/12086).
I have found that soldering SMT devices is less difficult than some people
imply. In particular, I found the reverse
(or self-closing) tweezers much easier
to use than a clothes peg which turned
out to be much too big to conveniently
handle tiny components.
I use solder paste in a syringe which
has a very fine nozzle, which allows a
suitably small amount of paste to be
applied to pads. The fine point soldering iron is adequate for the soldering,
and I’ve only made one or two mistakes
which were easily corrected.
Thanks again, Tim, for some engaging projects that the grandkids have,
and will, I hope, enjoy.
Eric McAndrew,
Capel. WA.
Response: thanks for your feedback.
Note that when melting solder paste
with the tip of a soldering iron, the solder paste can splatter, causing solder
balls to make their way to unwanted
locations. Reflowing the solder paste
with hot air is safer, as long as it is
done carefully.
Article on capacitors desired
I second your reader’s request in the
November issue regarding a guide to
capacitor usage. While there are plenty of web pages covering aspects of
this topic, I would really value such
an article as I know I can trust what
you publish and that it would be up
to date.
At the end of your response, to show
how complicated this topic is, you
list all the various issues that would
need to be addressed. Surely that in4
Silicon Chip
dicates how worthwhile such a guide
would be.
Kim Windsor,
Melbourne, Vic.
Response: we agree that it would make
for a good article and plan to start
working on it soon.
Oscillator rotary encoder reversed
I would like to thank Silicon Chip
and Andrew Woodfield for the Pocket
Audio Oscillator kit (September 2020;
siliconchip.com.au/Article/14563), it
works well, is easy to use and I love
the readout.
The supplied kit needed a few minor construction hacks and interpretations but nothing insurmountable.
I built the kit following the layout of
Fig.3 on page 46. But I noticed that
the frequency decreases as the knob
is turned clockwise.
I assume that either the rotary encoder is sending the opposite command to the ones that were used in
the prototypes, or that the 1.8kW and
3.9kW resistors in Fig.3 are swapped.
I swapped those two resistors and the
unit is operating correctly.
I understand the reasons that the
maximum frequency is 10kHz, but I
would find it far more useful if it could
get to 18kHz or maybe 25kHz, even
with excessive distortion and a flaky
readout. I can’t hear these frequencies;
I am just trying to catch the distortion
caused by them.
I really appreciate the magazine as
it has a nice mix of topics. You folks
are making many people happy, stimulating a swag of future professionals,
exposing theoretical types to a lot of
real-world experiences etc. In other
words, doing a bloody magnificent
public service!
One of my many pleasures/aims/desires in life is to gently work at making the world a better place. Thank
you for your efforts in that direction.
Well done! Before Silicon Chip, I read
Australia’s electronics magazine
Electronics Australia, and I was reading electronics magazines even before
that – struth!
Len Braithwaite,
North Sydney, NSW.
Response: we built our prototype with
the resistors in the positions shown,
and it worked correctly, so we have
to assume that different batches of
encoders can have the encoder pins
swapped. That’s frustrating, especially
since it’s almost impossible to tell until
you’ve mounted the encoder, but luckily swapping those two resistors is all
that’s required to fix it.
Vintage Radio index at Radiomuseum
We have put up an index on www.
radiomuseum.org to help enthusiasts
locate models mentioned in Silicon
Chip Vintage Radio columns in our
‘museum’. You can find a link to the
latest version of the index (as a PDF)
at the bottom of this page: siliconchip.
com.au/link/ab5o
Gary Cowans, Australian
Administrator for Rmorg,
Woodvale, WA.
Lack of DAB+ reception in tunnels
Unless my memory is mistaken or
technology has changed over the years,
the lack of digital radio reception in
Sydney tunnels is due to the way the
system is set up. If the setup was purely a high-gain antenna feeding a highpower amp connected to leaky coax,
then every AM and FM service that can
be received outside the tunnel should
be received inside the tunnel.
However, this is not the case. You
will find that only the mainstream Sydney broadcasts can be received in the
tunnels. For example, I have no trouble receiving 2GO/MMM Central Coast
107.7FM or The EDGE 96.1FM in Sydney in general, but not in our tunnels.
Way back in my Telstra days, about
20 years ago, I attended to a data service fault at one of the tunnel control
siliconchip.com.au
centres. In one of the rooms, there were
racks of AM and FM receivers and corresponding transmitters.
All radio reception in our tunnels
has to have the ability to be interrupted
for tunnel announcements and emergency information. The only way to
do this is to bring each radio service
back to audio with a receiver, feed that
audio into the info switch and then
back into individual transmitters for
that corresponding station.
When 2UW was multicasting on
both AM and FM before it officially
stopped its AM transmission, it took
about four weeks to get the FM reception in our tunnels.
Hence the lack of digital reception
in our tunnels. I retuned my digital radio, and currently there are nearly 70
services spread across the three digital
frequencies of 9A, 9B and 9C. I can see
several problems with retransmitting
these services in tunnels.
Firstly, every tunnel will require at
least another 70 individual receivers
to bring each station back to audio to
feed via the info switch. This is complicated by the fact that the bitrates
for stations can vary from 32kbps (eg,
The EDGE) up to 128kbps or more
(2CH, 2GB).
These individual audio streams
would then have to be fed back into
the appropriate transmitter in the
correct slot set up to the right bitrate.
This could add to the 10-or-so seconds
delay already heard in DAB+ broadcasts, compared to the same content
on AM or FM.
Then there is what I think is the
biggest problem, the constant reshuffling and changing of digital stations.
In the early years, 2DAY only had one
service, now it has six. What problem
will this cause the arrangement of digital in the tunnels? I can’t imagine a
simple solution.
Simon Kareh
Penshurst, NSW.
Calculating series
& parallel resistor values
On page 108 of the October 2020 issue, there is a link to a suggested website for calculating series and parallel resistors. That site works OK, but
you might find this one more useful:
siliconchip.com.au/link/ab5r
It has conversions and calculators
for 24 types of data, including series
and parallel resistors and capacitors. I
won’t list the other items, but I’m sure
6
Silicon Chip
they will be useful to many people. It
also includes a section to request an
additional calculator if needed.
Bob Denton,
Hastings, Vic.
Experimenting with PV hot water
I have seen a few articles in Silicon
Chip over the years about using solar
panels to generate power for an electric hot water system. This interested
me, but it never seemed feasible.
However, second-hand solar panels
are now cheaply available on Facebook
and Gumtree. Also, technology has improved to reduce the cost of necessary
devices further. So, I have made up a
system that is working well. It only
uses two 250W panels, as it is just a
project to see if it stacks up.
It is still a work in progress, as I am
presently manually switching the inverter on in the morning, and off in
the afternoon.
I am using an ESP32 to monitor the
solar power, and this is currently powered from a mains plugpack. In the
near future, I will be adding a DC-DC
converter to power the ESP32, and automating the stop/start for the inverter
depending on the available light.
I am using a 60V, 2kW “power frequency inverter board” sourced from
AliExpress for $50. This board produces a sinewave from the DC supply
voltage, giving around 36V AC from
60V DC. This is then fed to a large,
heavy transformer to step up the voltage for driving the 3.6kW element in
my hot water system. The efficiency
of the inverter/transformer arrangement is 80%.
I connected a Variac into this system
to find the optimal voltage to drive the
hot water element. Rotating it allowed
me to find the maximum power point
(MPP). Above the MPP, the power
from the panels decreases exponentially. Unfortunately, the MPP is not
static, and changes with clouds, time
of day etc.
To avoid going past the MPP, I selected a transformer with an output
voltage slightly less than the peak
with the panels in direct sunlight. This
compensates somewhat for the many
cloudy days in Cairns, but means I am
not extracting maximum power from
the panels during excellent sunny periods. So it’s a bit of a compromise, but
it works reasonably well.
The ESP32 sends solar data to a
Raspberry Pi, which uploads data to
Australia’s electronics magazine
PVOutput at pvoutput.org/intraday.
jsp?id=30164&sid=79430
Now that the concept has been
shown to be feasible, I plan to set up
a bigger installation with eight solar
panels driving our primary hot water
system (which has a 2.4kW element).
When it rains for a month in Cairns,
the backup option is to have a threepin plug on the hot water system, so I
can manually change it over to mains
power.
I estimate the total cost outlay for the
bigger system will be recouped within 1-2 years if I build it using secondhand panels.
Sid Lonsdale,
Cairns, Qld.
Micromite Plus capacitor problem
I came across a problem with the
Micromite Plus recently. When I upgraded to MMBasic 5.05.03, one of my
MM+ boards would not run the DAB+
digital radio software. It crashed many
times every second, rebooting with a
“bus error”.
My other Micromite crashed differently; it would throw “font #16”
or “font #8” errors, despite neither of
them being used by the BASIC program. Versions 5.05.01 and 5.05.02
both worked fine on the same hardware and with the same BASIC code.
I had seen this sort of thing on a previous (old) PIC32 design I had built
years ago, and it turned out to be the
10µF capacitor on the PIC32’s Vcap pin.
Increasing the Vcap capacitance fixed
the problem both then, and again now.
I piggy-backed a 47µF tantalum
capacitor onto the 10µF X5R on the
micromite board, and the problems
went away. I guess that 5.05.03 is ‘exercising’ the internal 1.8V rail a little
harder than previous MMBasic versions exercised it.
It may be that either that the 10µF
value specified in the data sheet is
marginal, or the capacitors supplied
in the Silicon Chip Micromite kits are
marginal or not as low in ESR as they
are claimed to be. Either way, the fix
is easy.
Stefan Keller-Tuberg,
Fadden, ACT.
Response: we purchase brand-name
10µF X5R capacitors (eg, Samsung
or Taiyo Yuden) from reputable distributors. Their ESR ratings are much
lower than the maximum of 1W specified by Microchip; they should be in
the range of 0.01-0.1W. So we suspect
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Silicon Chip
that your first suggestion, of the 10µF
specification being marginal, is the
correct one.
Of course, nominally 10µF capacitors can have values of around 8-9µF,
or even lower at elevated voltages and
temperatures. Still, we thought that
the person writing the specification for
the PIC32 would have taken that into
account. Regardless, it looks like we
will have to switch to supplying 15µF
or 22µF ceramic capacitors in future
kits to solve this.
I thoroughly enjoyed the article on
OBD2 (September 2020; siliconchip.
com.au/Article/14576). When I first
came to Australia, fuel injection, engine management and electronic ignition systems were still in their infancy.
It seemed at that time that Bosch had
a monopoly on the various electronic
modules used.
I have no idea how many Bosch 024
ignition modules I fitted or how many
complete distributors I fitted to various
vehicles (especially the early Ford Falcon with centrepoint injection). I used
to exchange one of those distributors
pretty much every day.
We overhauled the old unit in-house
with new bushes and sensors, except
where the shaft itself had worn. I became a dab hand at reinserting those
distributors back into the engine and
slotting them into the oil pump feed,
which was a hex-headed drive deep
in the bowels of the motor.
That vehicle had a rudimentary diagnostic system which would flash a
light plugged into a socket under the
bonnet. You could then trace out the
fault with a wiring diagram.
We also saw a lot of imported vehicles with various methods of diagnostics, usually by shorting a particular pin to GND and watching the CEL
(check engine lamp) on the dashboard.
Subaru had a few harness connectors
below the steering shaft and above the
driver’s knees, and connecting two
would start the CEL flashing.
Then came the Holden VL Commodore with the Nissan engine. Oh, what
a car, very fast and powerful but with
a few problems. For example, the optical pickup in the distributor (crank
angle sensor) had a plate with holes
punched through it to send the crank
position and RPM to the ECU.
Those sensors gave a lot of trouble,
Australia’s electronics magazine
as did the mass airflow meter also fitted to this Commodore. That optical
disc could also be inserted into the
distributor the wrong way around, resulting in a misfire on the number four
cylinder. I also saw several of these
vehicles with the optical slots filed
wider, which I was told elicited a bit
more power from the engine.
The onboard diagnostic system was
activated by turning a very small variable resistor through a small aperture on
the side of the ECU, with the ignition
on but the engine not running. Considering the ECU is behind the left-hand
kick panel, this meant lying down on
the floor in front of the passenger seat
to turn that resistor.
There are also two LEDs inside that
aperture, one red and one green. The
red showed tens when flashing, and
the green showed the ones. Two red
flashes and two green flashed meant
the code was 22. Those same LEDs
would show the sweep of the voltage
coming from the oxygen sensor when
the engine was running and the sensor up to temperature.
That ECU also had inbuilt testing; on
the initial DTC readout, several codes
would be sent. It would send a code for
the throttle position sensor, cleared by
opening and closing the throttle. Then
we would see a gear position sensor
fault, cleared by moving the gear selector from park through each position
and then back to park.
Next would be a start inhibit fault,
cleared by just quickly flicking the ignition switch into the start position.
Usually, the last inbuilt test code was
for the air conditioning and again, cycling the A/C switch on then off would
clear that code. Next came the actual
trouble code(s).
The company I worked for at that
time spent a large sum of money on a
diagnostic package which connected
to various engine points: the ignition
coil negative, an inductive sensor on
the cylinder number one plug lead, a
second on the ignition coil to distributor lead, a pair of leads to the battery
terminals and one to the battery connection on the alternator.
With the DFI system (direct fire ignition or wasted spark ignition) in
the next-generation Commodore, our
diagnostic package was updated with
new software and a new sensor lead
package to help find problems on a car
with no distributor and with multipoint injection.
siliconchip.com.au
I fixed a great many ECUs in my
time; most had burnt out transistors
and components that had been destroyed because someone had tried
to jump-start the car with the jumper
cables the wrong way around.
I also saw many transmission sensors and solenoids fail, especially
when people used standard transmission fluid (DEX III) instead of the
automatic transmission correct fluid
(TQ95). Standard fluid has an additive which strips the layer of varnish
from the coils in the solenoids, causing all kinds of problems; TQ95 does
not have that additive.
When I left that employer to start
work in a whole new town, I discovered problems with the ECU used in
the Mitsubishi Magna. The electros
used in that ECU would leak or burst,
and that area of the PCB would heat up,
eventually burning a hole all the way
through the PCB! It was an easy diagnosis; you could smell the burnt ECU
as soon as you opened the car door.
I would repair the PCBs where I
could, but a great many had large
holes and severe damage. These required a new ECU to be fitted. I made
sure that the suspect electros were replaced with high-quality components
before doing so.
After that, ECUs started becoming
more complicated. They handled not
only engine management and transmission control, but also air conditioning and climate control. Then security
was added, keyless entry, cruise control, anti-skid braking and SRS (supplementary restraint systems), ie, airbags and seat belt tensioners.
Then we had a body control module;
the list goes on and on until we reach
today’s vehicles, with multiple computers controlling an entire library of
systems including drive-by-wire and
intelligent braking, intelligent cruise
control, lane centring, blind spot warnings and self-parking.
I imagine that in the years to come,
manufacturers will master all the issues with self-driving cars, flying cars
and myriad other science-fiction inventions.
Dave Sargent,
Maryborough, Qld.
Preparing for disaster
Silicon Chip is a fine magazine. I
know what it’s like to edit a technical
journal, having managed two so far. I
have also been a technical writer in
siliconchip.com.au
charge of producing responses to requests for tender where risk management was a major factor.
I have fitted Solar PV panels on my
roof to learn about using El Sol for electric power. Your approach on backup
power (January 2020; siliconchip.com.
au/Article/12215) left me wondering
if there were a better way to achieve
your end.
So, I went back to some of my writings on risk management, in particular,
based on AS/NZS 4360. Here is a generalised risk management approach
that can be applied to all manner of
potential problems we face.
1. List every possible event that
could lead to damage or loss.
2. Assess the consequence of each
such event.
3. Estimate the probability of occurrence of each precipitating event.
4. Multiply the consequence by
the probability for each precipitating
event. List these in decreasing order.
5. Assess the cost of dealing with
each event, whether attenuating or
eliminating each precipitating event,
or providing a work-around for the
inevitable.
6. Put these mitigation costs against
the products list from step 4.
7. Discuss the results of your analysis with others likely to be affected.
8. Make plans for agreed mitigations.
If that seems very complicated, consider the following:
1. You might want to focus on just
a few nasties such as loss of electricity, loss of gas pressure, water management problems (loss of potable water,
sewerage or flood), transport disruption, damage to roads, land management issues (eg, erosion, landslide,
tremors or earthquakes).
2. Calculate the consequences in
monetary terms. Look to insurance
firm valuations if unsure.
3. Energy providers can tell you the
likelihood and duration of outages
based on historical records. The Bureau of Meteorology can provide estimates of temperatures, rain, wind and
wave movements.
State governments can probably
tell you the likelihood and duration
of water management failures; they
can also tell you the likelihood of unplanned events, such as road, rail and
bridge disruptions. Local councils can
advise on land management issues,
such as anticipated subsidence, road
resurfacing.
Australia’s electronics magazine
December 2020 9
even though we were sitting by the phone. We’ve since pur4. Wilfredo Pareto observed that 80% of the costs of dochased an office mobile phone, so we can redirect calls
ing things were accounted for by around 20% of the inwhen necessary.
puts. This has become known as the 80/20 rule. Your list
We spent hours with NBN tech support to no avail. So
of consequence-probability products will probably show
we decided to try rebooting the Telstra-supplied NBN routthis effect; ie, the first few items in your list will account
er, which was working fine for internet access at the time.
for the majority of your potential woes.
That fixed it.
5. For each of the items high on your list, identify several solutions to deal with each event. These might preComments on backup power and DCC
vent the untoward event or provide a work-around because
Thank you for both the January 2020 and the February
the event is inevitable but unpredictable (eg, running the
2020 editions of Silicon Chip. As usual, they were worth
fridge on a UPS in case of a possible power outage). Or you
reading.
might decide to take out insurance against it, or consider
The January 2020 Editorial Viewpoint and the accompaputting up with the nuisance (eg, wear warmer clothes if
nying article on emergency backup power raised the quesyour heater fails mid-winter).
tion: is it economical to maintain emergency backup pow6. By listing the costs of your ‘solutions’ against the
er? To decide, there are two basic questions. How much
consequence-probability products, and running a cumupower is required, and for how long?
lative total on the solutions, you get an idea of the size of
For a refrigerator, the cheapest and most reliable method
your problem(s).
for short term backup is to maintain “freezer bricks” in their
7. Present the results of your analysis to your family.
RAYMING
TECHNOLOGY
frozen state and for the long term, maintain a working petSome solutions may require
the co-operation
of neighbours
engined generator.
Batteries are simply not economical
or local authorities.
PCB Manufacturing and PCB rol
Assembly
Services
for
the
occasional
short
term power failure.
8. How will you pay for
your
solutions?
For
instance,
Fuyong Bao'an Shenzhen China
For our ‘must-have’ electronic devices, a generator is
some insurance firms offer incentives to prevent problems,
0086-0755-27348087
overkill except for extended power outages, and batteries
such as by offering reduced
premiums on home and conSales<at>raypcb.com
become more viable. Regardless, our governments and the
tents insurance if you install
a burglar alarm, or a UPS for
power suppliers will do their best to maintain power and
your freezer.
www.raypcb.com
to restore it when it is lost.
Brian Clarke, BE, MBA, PhD, CPEng, Fellow Eng
I have been trying to develop a DCC interface, which
Aust, IPEC Eng (Aust), Loftus, NSW.
has taken most of my energy of late. The DCC standard is
such a mad dog’s breakfast, and I had written quite a large
NBN reliability not as good as POTS
comment/complaint about it, but decided not to send it to
I have been on NBN for 2½ years and still have problems
you. It was more appropriate for a model railway magazine.
from time to time. When first connected, I lost my landline
I was hoping to get some tips for my system from the DCC
number and had to have this number redirected to my mostation article in the January 2020 edition (siliconchip.com.
bile until it was fixed. Even now, I lose my landline conau/Article/12220), but I was disappointed. However, the
nection and have to switch off my modem for five minutes.
project did introduce me to the BTN8962TA half-bridges
When the Telephone Directory came out early last year,
and they are impressive. If I didn’t have a large quantity
after 25 years I was no longer listed because I had changed
of N and P channel FETs, I would use them.
to the NBN and had to apply to be relisted. If I had the
I’ve found that I could not create a DCC station using
chance to go back to the old reliable system, I would do
a PIC microcontroller alone. I was forced to implement
it in a flash. I think the NBN should be renamed to No
a double-buffered counter using a few discrete logic ICs
Bloody Network.
to create the DCC waveform and use the PIC to control
Richard Cannan,
it. The reason was jitter in the polarity reversals of the
Warilla, NSW.
DCC waveform. The small PICs that I wanted to use have
Comment: we had a day-long dropout of the phone sera double-buffered PWM duty register but not a doublevice at our office a few months after switching to the NBN.
buffered period register.
It was frustrating because customers could not reach us
RAYMING TECHNOLOGY
Fuyong Bao'an ,Shenzhen, China Tel: 0086-0755-27348087
email: sales<at>raypcb.com web: www.raypcb.com
PCB Manufacturing and PCB Assembly Services
10
Silicon Chip
Australia’s electronics magazine
siliconchip.com.au
Considering that the DCC standard allows for a large
period variation of the “0” pulse but only a few microseconds for the “1” pulse, it was impossible to ensure that
the necessary precision would be met using an interrupt
service routine without a double-buffered period register.
I then wondered about the Arduino that was used in
your project. What did the programmers of DCC++ do? I
checked the specifications of the ATmega328P, and found
that the Timer1 module has a double-buffered period register. But there was no mention in the October 2018 project of the quality of the DCC waveform. I can only assume
it was acceptable.
The project did raise one big concern with me which I
believe is also partly to blame for the susceptibility of IoT
devices to hacking. That problem was the subject of the
February 2020 Editorial Viewpoint.
Unless a person is very familiar with a language and
particularly with tricks and short-cuts, it is very easy to
miss flaws in the routines. When using a library, how many
programmers check the validity of its routines before using them? I doubt that there are very many, and I am sure
that inexperienced programmers will use anything that is
stated to do a task without question.
George Ramsay,
Holland Park, Qld.
Comments: I believe I covered the reasons for choosing
a battery backup system quite thoroughly in the article.
Granted, I had a somewhat unusual reason for preferring
batteries. If you have the space to operate a generator,
don’t need automatic fail-over and are willing to do the
maintenance to keep the fuel fresh, it is indeed the cheapest option for a given amount of power over a long period.
But keep in mind that you can get much cheaper batteries than the one I bought. For example, Rockby is currently
selling a 12V 110Ah AGM deep cycle battery for $291.50
(Cat 38698, pickup only). Add a 2kW modified sinewave
inverter from Jaycar (Cat MI5024, $299) and a charger you
probably already have, and you can keep a typical fridge/
freezer running for around 24 hours for less than $600.
Granted, Jaycar’s Cat MG4508 2kW inverter generator
will keep the same fridge/freezer and other appliances running for a lot longer for just $100 more. But I think both
solutions deserve consideration.
Regarding DCC, if you have precise waveform generation requirements, it pays to check the microcontroller data
sheets carefully to choose the best one. Micros designed
for motor control generally have much more sophisticated
and precise PWM generators, and keep in mind that serial
interfaces are often a good way to generate an accurately
timed pulse train.
Another factor to consider is that some of the better
micros (eg, PIC32s) allow you to set interrupt priority levels.
So you could have a timer interrupt generating a pulse train
set to maximum priority. Communications interrupt handler
like those for USB or serial can then be set up with a lower
priority so that they won’t interrupt the critical timer ISRs.
You are right that blindly using libraries can cause problems. We had many problems with some popular software
I2C libraries, and when we had a look at what they were
doing, it was pretty clear that the authors either hadn’t
read the I2C standard or didn’t understand it! For good
security, you either can’t rely on third-party communications libraries, or you need to audit them.
SC
siliconchip.com.au
Helping to put you in Control
Optical Tipping Bucket Sensor
Hydreon RG-15 Solid State Tipping Bucket
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Signal Isolator
Monitor solar outputs with this signal isolator
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4 channel Current/Voltage Input Indicator
The SWP-99X meter is intended for measuring
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PID Temperature Controller
N1030-PR Compact sized PID Temperature
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SKU: NOC-320
Price: $90.50 ea + GST
RTD Temperature probe with screw fixing
This PT100 RTD sensor has screw fixing
for surface temperature measurement.
The 3 wire cable has a silicone sheath and
is 1 metre long. Temperature range is -50
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4 Channel Opto-Isolator
4 independent channels with switch-selectable
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PR200 programmable relay 24VDC
A universal and easy-to-use controller designed in a plastic
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For Wholesale prices
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Ph: (03) 9708 2390
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Prices are subjected to change without notice.
Australia’s electronics magazine
December 2020 11
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