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MAILBAG your feedback Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd has the right to edit, reproduce in electronic form, and communicate these letters. This also applies to submissions to “Ask Silicon Chip”, “Circuit Notebook” and “Serviceman’s Log”. Australia’s history of manufacturing electronic components Many people may not be aware of the extent of electronic component manufacturing that once occurred in Australia. We made just about everything necessary at the time, such as valves (vacuum tubes), resistors, transistors, transformers, etc – even solar cells. I recently tried to donate some examples of discrete Australian made electronic components to Victorian museums (some pictured), but sadly, they weren’t interested. Perhaps a collection should be established somewhere, including a museum collection, as a repository of Australia’s former manufacturing past. Dr David Maddison, Toorak, Vic. Comment: We welcome comments from readers suggesting a museum that would be interested in such items. Perhaps the Powerhouse Museum in Sydney would want them. Modifying RF signal generators for better performance I am writing regarding the El Cheapo Modules article on the 35MHz-4.4GHz Signal Generator in the December 2021 issue of Silicon Chip (siliconchip.com. au/Article/15139). I have bought several similar modules from sellers in China – some standalone synthesizer boards and 4 Silicon Chip other boards with an onboard microcontroller and an LCD screen. Some use the ADF4351 or the ADF5355 synthesizer chips, while others use the MAX2870. I recommend using the standalone boards as shown in the photograph below. There is a mountain of information on interfacing these boards to an Arduino Uno/Arduino LCD shield or a PIC microcontroller. Free Arduino sketches are available to control the frequency output, or a HEX file in the case of the PIC microcontroller. This approach gives you a considerable amount of freedom to tailor the Arduino sketch or HEX file to your own needs. I am currently working on the ADF5355 standalone board depicted with an Arduino Uno/Arduino LCD shield. I have greatly improved the board’s performance by replacing the LT1763 power supply chips with the ADM7150 series (5V/3.3V), which have dramatically lower noise (1μV RMS compared to 20μV RMS). The 5V rail is the one where noise really matters. Cleaning up the 3.3V rails had much less influence on the quality of the RF output. I am planning to use the improved board to extend the range of my RSA3030-TG when examining some of the higher frequencies, around 4-6GHz. It is noteworthy that Analog Devices’ very expensive ADF5355 development board also uses the ultra-low-noise ADM7150 voltage regulators. The result is a very low noise synthesizer – as good as the ADF5355 can deliver. I would avoid using the ADF5355 Board with GLCD that you can buy online. Sadly, these boards are just junk. The outputs look like they have been modulated with another frequency source – they are extremely noisy. The ADF5355 ‘black’ boards are better in noise performance, but you Australia's electronics magazine can only realize their full potential by modifying the power supply. I am planning to make a control board using just an ATmega328 chip. I will use shielded containers for both the ADF5355 board and the ADM7150 power board (5V and two 3.3V outputs), with a very precise (GPS-­ disciplined) frequency standard and perhaps some wideband RF amplifier modules to make a low-noise frequency synthesizer that covers the 54MHz to 14GHz region. This should not be too expensive to build – probably less than $300. I have a home workshop complete with a lathe, vertical milling machine, metrological instruments and an assortment of metal cutting tools. I will be using these to make RF enclosures for the ADM7150 power board and the ADF535X frequency synthesizer. Making quality RF enclosures out of aluminium stock is not hard, just time-consuming. However, in retirement, time is what I have in great abundance. Samuel Evans, Hackham West, SA. R80 Aviation Receiver kit changes I enjoyed the article on the R80 Aviation Receiver (November 2021; siliconchip.com.au/Article/15101) so much that I ordered one through AliExpress. On arrival, I was surprised to find the receiver, although very similar siliconchip.com.au Subscribe to JANUARY 2022 ISSN 1030-2662 01 The VERY BEST DIY Projects! Batteries 9 771030 266001 $ 50* NZ $1290 11 INC GST INC GST imagine life without them MetronoMes wi th Australia’s top electronics 8 or 10 LeDs protect to six amplifier modules up with our Multi-Channel Sp ea ke magazine r Protector Silicon Chip is one of the best DIY electronics magazines in the world. Each month is filled with a variety of projects that you can build yourself, along with features on a wide range of topics from in-depth electronics articles to general tech overviews. Published in Silicon Chip If you have an active subscription you receive 10% OFF orders from our Online Shop (siliconchip.com.au/Shop/)* Rest of World New Zealand Australia * does not include the cost of postage Length Print Combined Online 6 months $65 $75 $50 1 year $120 $140 $95 2 years $230 $265 $185 6 months $80 $90 1 year $145 $165 2 years $275 $310 6 months $100 $110 1 year $195 $215 2 years $380 $415 All prices are in Australian dollars (AUD). Combined subscriptions include both the printed magazine and online access. Try our Online Subscription – now with PDF downloads! All About Batteries; January 2022 The PicoMite BASIC Interpreter; January 2022 Hummingbird Amp; December 2021 Raspberry Pi Pico; December 2021 An online issue is perfect for those who don’t want too much clutter around the house and is the same price worldwide. Issues can be viewed online, or downloaded as a PDF. To start your subscription go to siliconchip.com.au/Shop/Subscribe to that in the article, is now at version seven, not six as described in the magazine. The circuit has undergone a major revision with the NE5204 and NE602 front-end replaced with TA2003 AM/ FM receiver chips and other chip changes making a simpler circuit diagram. The PIC controller has also been moved to the PLL board. The modifications to the squelch are no longer necessary as the TA2003 chip implements this. The receiver also includes mono coverage of the FM Broadcast band for those times you get tired of the endless aircraft movement calls. All in all, a good kit and easy to put together for someone with moderate skills and knowledge of circuits. The instructions, supplied on request, are in Chinese, and you have to work out from the circuit diagram where the ICs go, as they are different both in type and layout to the article featured in Silicon Chip. Nigel Dudley, Denmark, WA. Comment: see also the letter in the Ask Silicon Chip section of the January issue and Andrew Woodfield’s response to it. He has provided a translated instruction manual which we’ve made available from our website. TV sound levels are all over the place Thank you for printing my letter titled “Historical articles enjoyed” in the July 2021 issue. I got a great kick out of finding that you have printed one of my letters in your very popular magazine. But reason I am writing in this time is that I’m finding the sound levels are all over the place in the general television programming. I have a reasonable sound system that has been built up over the years in my loungeroom. While we have the level quite low and at a normal listening level, when ads or a news break comes on, the sudden increase in loudness is quite disturbing. I know that every television station uses compression to make the sound level sound ‘the same’ and give it ‘more punch’, but despite that, the sudden increase in level can be quite bothersome! It might not be as noticeable on a lot of televisions, even with a sound bar installed to increase sound quality. Changing from channel to channel often brings up problems with mismatched levels, and one has to readjust the volume then too. Many of the HD channels are down in level and need adjustment as they are lower in level than other programming. I think this is to do with the amount of channels that are transmitted on the one frequency. Stephen Gorin, Bracknell, Tas. Comment: We have noticed the same thing and it is infuriating. There is a simple solution but it would require all broadcasters and streaming services to adhere to the standard, which would probably be hard to achieve. Every stream/broadcast/video should have a dB offset encoded within it; just a simple number, so it should not be hard to do. This is the dB offset (positive or negative) needed to be applied to the volume level in a reference system (representing a decent sound system) to get the dialog in that program to a certain reference level. 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SKU: SXS-240 Price: $306.90 ea For Wholesale prices Contact Ocean Controls Ph: (03) 9708 2390 oceancontrols.com.au Prices are subjected to change without notice. Australia's electronics magazine February 2022  7 increase. You would then be able to enable a feature in your TV to automatically apply an offset to the volume level based off that number. So the dialog in all programs would be at the same level, regardless of how it is recorded or processed. This might need to be combined with some sort of compression technique to limit the maximum volume level (perhaps via a second coefficient). But we believe this would be much better than the current situation with each program having an arbitrarily different loudness level. Another amusing old magazine I have never replaced any components in it, and it still gives a perfect picture (from analog signals, of course) with a slight frame buzz, no doubt due to some of the electrolytics drying out. It is a hybrid valve/transistor set. Some time ago, I made a Heath Robinson modification so that I could receive the US Armed Forces TV, which was broadcast in NTSC. I only needed to adjust the vertical hold for the different number of lines and switch in the ceramic capacitor to change the sound carrier frequency. The simple modification worked perfectly! Christopher Ross, Tuebingen, Germany. What a surprise to open the November issue and see the image I sent in of the portable radio from 1936 (page 8). I recently came across a 1937 issue with the cover shown adjacent. With COVID-19 travel restrictions now lifting and caravans coming out again for the summer break, please do not leave the wife in the caravan cooking bacon and eggs while motoring to the next comfort stop! Graham Street, Auckland, New Zealand. Ultra-LD Mk.4 alternative transistor Vintage TV is still going strong My subscription copies of Silicon Chip (it’s a great magazine) seem to be arriving regularly in Germany now, albeit around the middle of the month. I was very interested in your Vintage section on the Sony TV. I thought it might be interesting to mention the TV I bought in 1970 (shown in the photo at the end of this item). 8 Silicon Chip Your response to the letter from I.P.V. of Karrinyup, WA (Ask SILICON CHIP, August 2021, pages 109-110) suggesting the IMX8-7-F as a replacement for the now unobtainable HN3C51F got me searching for a closer match. I found the HN4C51J, which appears to be identical to the HN3C51F except that the two transistor bases are tied together (hence it comes in a five-pin package rather than six), and the pinout is different. To accommodate the new pinout, the PCB will require slight modification. First, cut the PCB track between pins 5 and 6 of where the HN3C51F was originally located. Next, install a jumper between pins 6 and 2 in the original configuration. The HN4C51J may now be installed with pin 4 of the HN4C51J placed where pin 1 of the HN3C51F was to go. Cutting the track between the original pins 5 and 6 should be straightforward. The jumper between the original pins 6 and 2 might be more challenging. The easiest solution might be to fit the HN4C51J first, then install a ‘bodge wire’ from pin 3 of the HN4C51J directly to the pad of the nearby 68W emitter resistor. Mark Fort, Brassall, Qld. Comments: that should work. We agree that it will be easier to solder a wire after fitting the part. If doing this, make sure to cut the track thoroughly. If we revisit the design, we will adjust it to use this transistor. Having said that, we think substituting the IMX8-7-F will not affect performance, and it is a direct replacement with no PCB modifications required. More on Digital TV standards This email was prompted by Bryce Cherry’s letter, published in the November 2021 issue (page 6), regarding Australia's electronics magazine siliconchip.com.au DVB-T2 digital TV and MPEG-4 for Ultra HD TV and better spectrum utilisation (ie, more TV channels in the same bandwidth). I wrote to the Household Assistance Scheme administrators and requested MPEG-4 capability be compulsory, but also to not pay any antenna installer who used an antenna designed to receive any channel in the range 0-5A, pointing out that there will be no broadcasts on those channels and the antenna will produce less reliable reception due to noise. Now you cannot buy a new band 1/3 antenna. I also have made submissions to Standards Australia to make MPEG-4 compulsory, not optional. Examining the specifications for current TVs, it is difficult to see if they support both DVB-T2 and HEVC, which are needed for broadcasters to transmit Ultra High Definition TV, in competition with the video-on-demand companies. UHD from the internet requires HEVC, but DVBT2 is only needed for over-the-air broadcasts. If DVB-T2 is used for broadcasting, all receivers must be capable of receiving it or, a DVB-T2 set-top box will be required. They are used in some overseas countries. This is how we converted from analog to digital TV. Initially, HDTV used MPEG-2, but it was too data-­ hungry, so MPEG-4 had to be used. If Australian Standard AS 4933 in 2010 had made MPEG-4 compulsory, in 2015, all programs could then have switched to MPEG4, allowing most programs to go high definition. SD programs on TV are still using MPEG-2. We need an update to AS 4933 and AS 4599.1:2015 to include UHD and other new developments. In 2014, TV channels were restacked to allocate a block of consecutive channels to each transmitter site. Except for Darwin, all capital cities have their main transmitters in VHF’s channels 6-8, 10-12 (Block A). All other sites use one of these blocks: B (28-33), C (34-39), D (40-45), and E (46-51). Notice there is a spare channel in each channel block. The only exceptions are Alice Springs, Melbourne and Adelaide. These are for Community TV, which the Government is trying to push online, so they are only giving 12-months extensions to their licences. The other community stations went bankrupt under these conditions. Some remote towns have VHF and UHF, but the transmitters are in different locations. Why are Australian antenna manufacturers selling VHF/UHF antennas except for caravans? Alan Hughes, Hamersley, WA. Praise for Voice Modulator I just completed building Warwick Talbot’s “voice modulator” circuit from page 91 of the August 2019 issue of Silicon Chip (siliconchip.com.au/Article/11777), and it didn’t work. The carrier was audible at the output and the input signal was distorted. I noticed on the circuit diagram that the diodes are arranged in a bridge rectifier configuration. I then read that the diodes are meant to be wired in a circular layout, ie, anode to cathode to anode etc. I subsequently changed both the germanium and silicon diode orientation, and wow, what an amazing instrument! My circuit uses a cheap (about $15) square/sine/triangle generator board containing an ICL8038 IC, and I added siliconchip.com.au Australia's electronics magazine February 2022  9 Warwick’s circuit on Veroboard. I want to build another on one PCB to minimise the mess of wires! Was the error drawn by Warwick or the Silicon Chip graphics department, either thinking “bridge rectifier”? Ian Horacek, Essendon, Vic. Comment: Sorry about the drafting error which was introduced when we redrew the circuit. It was mentioned in the Notes & Errata section of the October 2019 issue and also on page two of our 2019 Errata Sheet. October issue enjoyed You have excelled again with your October 2021 issue. Congratulations to all involved. The article on Gravitational Waves is a beauty and the 2/3-way Active Crossover looks like it will be useful. I have already ordered the cute SMD Test Tweezers kit from your shop. David Humrich, Perth, WA. Comment: you weren’t the only reader who ordered that kit! We expected it to be popular but were still overwhelmed. We only caught up with demand in early November. The USB V Cable Tester project, which debuted in November, has also been extremely popular, again beating our expectations. While we were better prepared for that, it still took us a few weeks to catch up. Documenting old switchboards Last year, I got to visit a location I had visited several times in the 1980s when I was a kid. Last year it was wet, so I only packed my DSLR camera. However, a few days ago, another opportunity to visit arose, low wind and dry weather, airspace classification checked etc. The people who let me in were amazed that I could see the site from the air. While there, I was asked if I wanted to see anything else, so being me, I said “the main switchboard”. What a beauty it was, 1960s vintage, looking far more impressive than the main switchboards for a large major metropolitan supermarket. Needless to say, I took photos of it (and of the drawings that were with it). It has multiple boxes, each with a lever switch on the side and a small door on the front that took cartridge style fuses (a bit like a giant version of a 3AG or M205 fuse). Each area of the then-new buildings had two threephase cables going to two small cabinets with circuit breakers (one for off-peak night store heating and hot water, the other general power and lighting). That main switchboard also fed five existing buildings as well as outdoor lighting, swimming pool stuff and the caretaker’s house. The site had its own transformer outside as well. I didn’t touch anything as I knew that parts of it (quite possibly all of it) are still live. It’s definitely more interesting to look at than the switchboards at work, which are a mix of 1993 and 2018 vintage beige cabinets with boring rows of circuit breakers. Even the main distribution boards look boring. I have access to the plant room, being the in-store maintenance assistant. I suggest, if it is safe to do so, take photos of the older gear. It makes great visual references for drawings and other arts and also helps to record our built/industrial heritage. Darcy Waters, SC Wellington, New Zealand. intage Radio Collection March 1988 – December 2019 Updated with over 30 years of content Includes every Vintage Radio article published in Silicon Chip from March 1988 to December 2019. In total it contains 404 (not an error) articles to read, or nearly 150 more articles than before. Supplied as quality PDFs on a 32GB custom USB All articles are supplied at 300DPI, providing a more detailed image over even the print magazine. Physical and digital versions available Buying the USB gives you access to the downloadable copies at no extra charge. Or if you prefer, you can just buy the download version of the Collection. Own the old collection on DVD? If you already purchased the previous Collection on DVD, you can buy this updated version for the discounted price of $30 on USB (plus postage), or $20 for the download version. $50 PDF Download SC4721 siliconchip.com.au/Shop/3/4721 $70 USB + Download SC6139 siliconchip.com.au/Shop/3/6139 Postage is $10 within Australia for the USB. See our website for overseas & express post rates. 10 Silicon Chip Australia's electronics magazine siliconchip.com.au