6 Silicon chip Australia’s electronics magazine siliconchip.com.au
Atten ST-60 Soldering Station
+61 8 8346 4424 http://www.trip le poin t.com.au$99+GST
In retrospect, we probably should have used an
MCP73123 charger IC to avoid this concern. It is intend-
ed for charging LiFePO 4 cells. Unfortunately, it is not
pin-compatible with the MCP73831 as it only comes in
a DFN package, whereas we used the SOT-23 package IC
in our project.
The 9.4mA quiescent current figure is correct. Much of
this is consumed by RX1 as it needs to operate continu-
ously, waiting to receive data which is to be repeated.Comments on UHF Data Repeater
I just finished reading the article in the May issue on
the 433MHz Data Repeater. Bravo for its ability to handle
a wide range of “device-agnostic” signals. Note that this
repeater assumes ASK remote coding; some remotes may
well use noise-immune FSK (or better GFSK), and these
signals will not be repeated!
Note also that depending on placement, the repeater
may blindly repeat other folks’ 433MHz signals. It’s hard
to say whether this would be beneficial or mischievous!
I’m glad you used the LiFePO 4 cell, but they only go
as high as 3.7V on charge and then settle to a stable 3.2-
3.3V. My experiences with these little darlings indicate
very high reliability compared with LiPo. Some outdoor
equipment of mine is now in its sixth year of continuous
operation without any woes.
I’ve gutted LiFePO 4 -based solar security lamps for di-
verse 433MHz projects. Their inbuilt PV panel is usually
well-suited to the task, and they’re very well sealed for
outdoor use. Additionally, folks think they’re just a light
and don’t consider them invasive.
Also, I consider the Jaycar Cat ZW3102 receiver module
a much better and more versatile receiver than the other
one you’ve specified. This may be important when signal
levels are marginal.
It may be worth rustling up a 433MHz sniffer/direc-
tion finder to help constructors when “up a pole” siting
the repeater. Check out my instructions on building one
at: siliconchip.com.au/link/aaqm
Stan Swan,
Wellington, NZ.
Response: see the letter above regarding LiFePO 4 charge
voltages. The idea of hiding a wireless transmitter or trans-
ceiver inside a solar security lamp is a stroke of genius.
We published a simple sniffer design from Stan in the
January 2011 issue, which shows received signal strength
using LED brightness (siliconchip.com.au/Article/870).Report on Israeli lunar lander “Beresheet”
In the November 2018 issue of Silicon chip, I wrote an
article on the Beresheet lunar lander (siliconchip.com.au/
Article/11296).
This was to be Israel’s first lunar landing, and only the
fourth country to attempt a soft landing on the moon after
the Soviet Union, the United States and China. The pro-
ject was also mostly privately funded.
On April 11th 2019, Beresheet unfortunately crashed
during its attempted landing.
A full investigation as to the causes is still to be com-
pleted, but there is a suggestion that it was a failure of
the inertial measurement unit (IMU), which is thought to
have failed during the braking procedure from lunar orbit
in preparation for landing.RESEARCH LABORATORIES
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Phone: +61 7 4058 2022
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