You would need to power the main
controller section from 12V and the
motor driver section separately from
a suitable 180V supply. You could
use a 500VA+ mains transformer with
a 120V AC secondary (or 60V + 60V
in series), then rectify and filter the
output. Check that the transformer
can handle the motor startup current,
which likely will be well over 4A.
If building this project, please read
the relevant notes & errata in the 2017
PDF at siliconchip.au/Articles/Errata
Displays for 2.5GHz
Frequency Counter
I am having trouble sourcing the
four-digit, 7-segment LED displays
used in the 2.5GHz 12-Digit Frequency
Counter (December 2012 & January
2013; siliconchip.au/Series/21). They
are specified in the parts list as coming
from Futurlec, but they have no stock
of the blue type.
They can offer me a red type but
the forward voltage is only 2.4V maximum at 20mA. The blue variety is
rated at 3.2V <at> 20mA but can handle
4V maximum.
Advertising Index
Altronics.................................27-30
Dave Thompson........................ 103
DigiKey Electronics....................... 3
Emona Instruments.................. IBC
Hare & Forbes............................. 13
Jaycar................... IFC, 9, 11, 14-15,
....................................43, 67, 90-91
Keith Rippon Kit Assembly....... 103
I have some similar red displays
from AliExpress rated at 2V maximum
<at> 20mA. Should I use the AliExpress
parts, go with the alternative Futurlec displays, or wait for the blue ones
to come back into stock? It could be
a long wait.
Changing the resistors to suit the
alternative displays might be a solution, but what should their values be? I
have built the main board but the display is holding me up from testing it.
(E. B., Meadow Springs, WA)
● Readers asking where to find parts
that have been discontinued or are out
of stock is becoming something of a
theme. While Futurlec doesn’t have
stock of the displays we used, they are
still available from other vendors. For
example, AliExpress items:
• 1005005352398426
• 1005001606190533
• 1005003246695690
You could use displays with a different colour if they are easier to get.
Since, as you wrote, the red displays
will have a lower voltage drop at the
recommended segment current level
of 20mA, we suggest replacing the
eight 47W series segment resistors in
the counter display board with 150W
resistors to be on the safe side.
The resistors concerned are at the
upper left on the display PCB, looking from the front.
PIR Mains Timer
wiring question
I have built your February 2008
PIR-Triggered Mains Switch project
(siliconchip.au/Article/1751) from a
Jaycar kit (KC5455). I am using Jaycar’s
XC4444 PIR module. Unfortunately,
I’m a bit stuck on this last step when
connecting the PIR to the 3-way terminal block. The instructions state
that I need to put a link between the
ground on the PIR and the contact of
the normally-closed relay; could you
please elaborate on this?
Any help would be greatly appreciated. (E. C. H., via email)
● Before we get to wiring up the
PIR module, we’d better check that
it’s compatible with the PIR sensor
shown in the article. That one had two
normally-closed (NC) switch outputs,
ALARM and TAMPER. They were connected in series with one end to circuit
GND so that they would usually hold
the input low, but a resistor would pull
it high if either switch opened.
We downloaded the manual for
Jaycar’s XC4444 PIR module from
their website, and it appears to have
a much simpler arrangement with just
three terminals: Vcc, OUT and GND.
The OUT pin idles low but goes high
when the sensor detects movement
(presumably to Vcc). Therefore, this
appears compatible since it is also
low when untriggered and goes high
when triggered.
The specifications for that module
on the Jaycar website say it will operate
from 5-20V, and our circuit is powered
from 12V, so it should work.
The connections for the 3-way terminal block are as follows:
• Top terminal (+12V): goes to Vcc
on the PIR detector
• Middle terminal (IN): goes to
OUT on the PIR detector
• Bottom terminal (GND): goes to
GND on the PIR detector
Make sure you don’t get the +12V
and GND connections mixed up. SC
LEDsales................................... 103
LD Electronics........................... 103
Microchip Technology......... OBC, 7
Mouser Electronics....................... 4
SC Pico W BackPack................ 102
Silicon Chip Breadboard PSU... 66
Silicon Chip PDFs on USB....... 101
Silicon Chip Shop................ 89, 98
Silicon Chip Subscriptions........ 77
The Loudspeaker Kit.com.......... 97
Tronixlabs.................................. 103
Wagner Electronics....................... 6
104
Silicon Chip
Mgazine Errata and Sale Date for the Next Issue
Lazer Security........................... 103
Loudspeaker Testing Jig, June 2023: the 1kW resistor connecting to
LK1 that filters the phantom power for the microphone should be 100W,
not 1kW. It might work with 1kW, but it will depend on the microphone.
Also, because pin 2 of XLR socket CON10 (“HOT”) connects to the INsignal and pin 3 (“COLD”) connects to IN+, the microphone phase will be
inverted. To fix this, swap the wires to pins 2 & 3 of header CON11 on the
PCB. Finally, the labels of transistors Q1 & Q2 in the circuit diagram (Fig.3)
have been swapped, but they are correct on the PCB overlay and PCB.
Vintage Radio, Astor APN, May 2023: there were some errors in the
published circuit diagram for the set, mainly regarding the connection of
capacitors #35, #36, #38 and resistors #6 & #10. The circuit diagram has
been corrected in the online version of the magazine and has been made
visible in the free preview of that issue on our website.
Next Issue: the August 2023 issue is due on sale in newsagents by Thursday,
July 27th. Expect postal delivery of subscription copies in Australia between
July 26th and August 11th.
Australia's electronics magazine
siliconchip.com.au
