106 Silicon chip Australia’s electronics magazine siliconchip.com.au
ASK SILICON CHIP
Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line
and we’ll answer your question. Send your email to [email protected]Arduino IDE GCC
compiler bug
When compiling the software for
the Diode Curve Plotter (March 2019;
siliconchip.com.au/Article/11447)
in the Arduino IDE, I get the follow-
ing error:
Arduino: 1.8.4 (Windows 10),
Board: “Arduino/Genuino Mega
or Mega 2560, ATmega2560
(Mega 2560)”
C:\Users\JBA\Documents\schip\
Zener_DiodeTester\Zener
Diode_Tester.ino: In function
‘findTargetPowerIndexFloat’:
Zener_Diode_Tester:884: error:
unable to find a register to
spill in class ‘POINTER_REGS’
Could you please guide me to a so-
lution? (J. A., Townsville, Qld)
- This is due to a bug in the GCC com-
piler which is used by the Arduino
IDE. This bug appears to be intermit-
tent and is described here:
https://forum.arduino.cc/index.
php?topic=510473.0
You are using Arduino IDE version
1.8.4 and we used version 1.8.5 for this
project, so we recommend upgrading
your IDE version to see if that helps.
Alternatively, you may be able to up-
date the compiler by using the Tools →
Board → Boards Manager menu. Look
for “Arduino AVR boards” and see if
you can upgrade this to version 1.6.23.
Diode curve plotter
opto voltage ratings
Regarding the Multi Diode Curve
Plotter in the March 2019 issue
(siliconchip.com.au/Article/11447),
you have specified PC817 optocou-
plers. I have some similar “LiteOn”
LTV817 parts which seem much the
same, but the maximum collector-
emitter voltage is specified as 35V.
Since the boost converter in this
project produces around 100V DC,
will these optocouplers be OK with
switching this? (R. S., Emerald, Vic)
- They should be fine; even the speci-
fied PC817 optocouplers do not have a
100V rating. The optocouplers are in
series with the high-voltage supply,
so only a portion of it appears across
them. The software limits the voltage
across the optocouplers so that they
are not exposed to the full 100V.Diode Curve Plotter
discrepancy spotted
I have a couple of questions regard-
ing the Multi Diode Curve Plotter in
the March 2019 issue (siliconchip.
com.au/Article/11447).
I have received the PCB I ordered
from your Online Shop and noticed
that three resistors just to the left of
D1 are all shown as 10kW in Fig.2 on
page 67 but the PCB silkscreen, cir-
cuit diagram and parts list all show
the middle resistor as 1kW. I assume
that Fig.2 is in error.
The photo of the populated PCB
shows a nice neat 1μF capacitor.
Where did you get such a small and
compact polyester capacitor? All the
1μF 250V caps from the usual sup-
pliers have a lead pitch of 20-25mm.
The only small electro I could find in
1μF, 450V is RS Cat 365-4795. (P. C.,
Woodcroft, SA)- You are correct, the 1kW resistor
just to the left of and slightly above
D1 has been wrongly marked as 10kW
on Fig.2. We will publish an erratum.
The 1μF capacitor seen in the pho-
to is a 1μF 100V unit from Jaycar
(RM7170), which was used for proto-
type testing. It was fine running right at
its voltage rating; however, we thought
it safer to specify a 250V-rated capaci-
tor for the final version to give a bit of
headroom, as the boost converter out-
put can exceed 100V.
Which transformer to
use for Magnetometer
I want to build the Incredibly Sen-
sitive Magnetometer project you pub-
lished in your December 2018 issue
(siliconchip.com.au/Article/11331).
But the article doesn’t specify thepart number of the transformers used
as the sensing coils, and I am having
difficulty finding one with the speci-
fied secondary ratings of 12V, 10A. Do
you know where I can get one? (anon,
via telephone)- Pretty much any non-toroidal trans-
former with a 12V, 10A secondary
(or similar rating) should be accept-
able. For example, RS Cat 504-127
(siliconchip.com.au/link/aapt).
Alternatively, Tortech (www.
tortech.com.au/store/) sell 12V trans-
formers with a 150VA rating for $64
including GST.
Both of these transformers above
have dual secondary windings, while
the transformers used in the prototype
Magnetometer had a single winding.
For transformers with dual secondary
windings, connect them in parallel. It
should work with them connected in
series too, but the circuit would then
behave differently, and this has not
been tested.
The prototype transformers were
old stock of a lighting company, not
advertised on the internet; hence we
did not give specific part numbers.
The exact VA rating is not critical. For
example, 12V 15VA transformers are
suitable for detecting, through a tab-
letop, that someone has moved one’s
keys or mobile phone.
Sourcing Clipsal plates
for Dimmer project
Could you please advise where you
obtained the Clipsal 2000 series blank
plate and cover for the Versatile Trail-
ing Edge Dimmer project (February
& March 2019; siliconchip.com.au/
Series/332). I can’t find a local source
for them. (J. A., Townsville, Qld)- You need to order these from an
electrical wholesaler, one that sells to
electrical contractors including light-
ing, cabling, power points and the
like. They don’t usually have stock of
the specific Clipsal parts required, but
these can be ordered.
John Clarke purchased the ones used
in the prototype from Lawrence and