First we had Magnum PI and now we have Raspberry Pi. This is our own PI account of the Raspberry Pi – nothing new when it comes to comparing performance to competitive units of similar processing power but very much new when it comes to straight value. The Raspberry Pi’s WOW factor is of course it’s price (when compared to the Intel NUC which is of course of higher performance and costing nearly ten times more). The importance here of course is that a person learning to program does not need a high performance gaming machine – to bring education into all schools and not just the Ivy League ones the lower price point makes it all that more enticing. Continue reading “Things I can do with my Raspberry Pi”
Common and hopefully zany audio circuits
In the quest for building things quick and cheap here is a list of some of our Parts-Ring all-time favourites including links to websites with interesting information. Some of these circuits are really old and if we have plagiarised content we apologise up front – please drop us a line at firstname.lastname@example.org to have us remove this material.
Years back all power amplifiers seemed to use the 2N3055 (100W) or PL909 (200W) in the output stages. Yes there were other transistors available but the 2N3055 cost a fraction of a dollar and the output was more than sufficient to cause damage to one’s ear drums in a small to medium sized room. The PL909 or 2SD555s were a different beast, expensive but more then ample. Think of Pink Floyd’s music system and you could be rest assured that main stream music groups of the era were using HiWatt or possibly Phase Linear equipment. Continue reading “Zany Audio Circuits – Fun Stuff”
A Lazy Day with Class D on the Brain
With nothing to do last Sunday I decided to do some research on class-D audio amplification development over the last five years. For those new to Parts-Ring.com or to electronics you’ll at some or other stage come across this classification and whilst it boasts all the bells and whistles of a good class AB amplifier, beneath the veneer lies a very sophisticated beast. I’m all for KISS (Keep it Straight and Simple) but you know what, there is merit in using a class D amplifier, lots of electronics inside. Let’s have a look at what cooks.
With China being the largest consumer electronics goods exporter, with South Korea no doubt sitting somewhere close behind it’s not surprising to see a huge growth in export of semiconductors globally. Research statistics are confusing as much of what is read on the net is either old or ambiguous. If we stick to what we see there are four electronic companies that appear to be the leaders: Apple, Sony, Samsung and LG. The reality is we only notice what we know, and knowing is the key, in other words: Brand awareness. Depending on where you live, this could be a traditional mud hut to a Star Trek space vehicle certain products fascinate certain users as much as the rich and famous gravitate towards their own specific niche manufacturer. One thing is certain though, as the electronics sector – digital and analogue, becomes more sophisticated the trend for manufacturing companies to seek out components based on performance and price becomes more important. In this though we also have the hidden dangers of batch failure and worse still, dodgy-rated components. Sony has a reputation for having an R & D division second to none but nothing stopped their laptop batteries from overheating and causing a huge recall. Ten out of ten to this company for having a strategy in place and accepting responsibility – many don’t. The question then arises, how many other companies are supplying dodgy components to the consumer market and here we look no further than semiconductors in general.
I was in the consumer electronic repair business for about ten years, in all, electronics for about twenty five in total, much of this being in the marine industry. Nothing like consumer products to boggle the mind when purchasing replacement parts to conduct a repair. Imagine purchasing a replacement part which causes more damage to the adjacent circuitry than the failed part. To tell the truth, nothing new. Many hours of trying to repair television receivers wasted because the new line chip was faulty. Trying another one produced the same results. Batch failure or deliberately bombarding the unsuspecting public with faulty components? A friend working at a scientific research station in my home town complained of similar incidents. Rebadged Toshiba transistors. The question then arises, just how infiltrated is the semiconductor market with bogus components?
The Truth Be Told
This is not a new subject, just a subject touched by my own experiences in the electronics field. Sadly the manufacturer of these bogus devices carry no remorse. There are few watchdogs monitoring this and if there are it’s a pity they haven’t become more transparent in their own research and findings. One thing is certain though – it’s not uncommon and parts procurement is becoming more difficult if we are looking for the perfect match. Asia, China in particular has become the scapegoat – possibly not without reason but unfortunately many resellers of counterfeit transistors or semiconductors in general are blatantly aware of their ‘bad’ behaviour – profit being the main driving force. As it always is. The sad part is that one buys a part to fulfill a specific purpose – in good faith you spend hours ‘doodling’ around a circuit which fails because not of your own doing but because of the unscrupulous supplier or manufacturer.
A certain power supply manufacturer had a high failure rate of a specific diode in the circuit – whom accepts liability for the unreliability of these power supplies? Remember the Fujitsu hard drive faisco in the early 2000s? Hard drive manufacturers certainly get credit for their unreliable drives, the manufacturer of the dodgy chip not. Ask any consumer which drive he prefers and they will tell you, based on the unreliability of a previous drive he had. Yet, sadly every drive manufacturer out there has brought out a certain drive which proved to be unreliable. This is never a deliberate thing – the two most popular drive manufacturers currently, WD and Seagate have both had their own set of unique issues and sadly is does no good to their reputation but yet we should never become biased. They both produce drives which will eventually fail like anything mechanical – the user just does not get it. Drives should be backed up. Then the consumer complains about the back up drive failing. Electronic components fail, more likely the parts that run the hottest or where value does not meet with design criteria. In a CRT television receiver most failure can be credited to the power stages, from line and frame outputs to the power supply. Colour drivers as well. But there is nothing worse than replacing a component with the same part number and it fails as well, only to find out after exhaustive testing that the component was just duff.
Toshiba or Tobisha
Semiconductors are now been exported in their millions – how many of those Toshiba marked components really come from Toshiba which by the way is a highly rated component manufacturer. The ‘Television’ magazine from the UK meant for the repair industry on occasion did warn about fraudulent components on the market but one would never be the wiser would one. I don’t recall an expose on any specific company but fear mounts when one realises that many such components may find their way into the aviation sector. In my ten years in the merchant marine, all components were supplied with batch number, manufacturer in sealed packaging. You would pay up to five times the normal electronic store price but the product worked. I tried to repair a Raytheon radar with equivalent diodes purchased at a TV store as a matter of emergency and it did not work, the 1000V PIV rating or current handling capacity just did not meet up to the design standards of the radar. The diodes tested fine, they were same switching speed, same current rating and same reverse voltage rating but it did not function in circuit. Guess what? They were the same part number. This not only proved to be very embarrasing but dangerous. Radar is a navigational aid but seafarers rely on radar, especially in poor visibility. What about medical usage?
Medical and Aviation Grade
I have only repaired two pieces of medical equipment and in both cases the manufacturers shipped the replacement components free of charge to my store. Again, like the marine radar or SSB transmitter the components were very clearly marked, batch number, manufacturer and sometimes serial number. There is a lesson to be learnt when moving from the marine, aviation, military and medical sector to the ever popular consumer sector – manufacturers carefully select specific components to fulfill a specific function. Repair personnel should never veer off this path and this is where I sometimes worry about the cheaper alternatives of today. Many years back one could ascertain quality by just looking at the packaging – this is not the case today. There are watchdogs and standards committees, there are people flying solo to bring companies bringing out fraudulent components to book but the fact is – dicey manufacturers are getting more clever. Critical components MUST be replaced by the original, stick to the original bill of material and stick to Engineering Change Notices. When it comes to consumer products Sony is a company that stands out for their stickiness in product design. Sony may be competing against companies producing goods at more competitive pricing but this is where paying more justifies the purchase. Likewise, why would Furuno be rated as one of the most reliable manufacturers in the world? R&D and learn from our mistakes.
The Chinese export market has grown in leaps and bounds over the last two years (this is the time span I have noticed the growth, not an accurate indicator but the time I have noticed the sudden and especially recent abundant release of documentation, schematics and application notes). I do believe that most Asian exporters are acting in good faith but do stick to the old adage, there is nothing like a free lunch. We at Parts-Ring feel that there is going to be an abundance of dodgy components been released onto the market – we had it before and we’ll just get more of it. Stick to well known manufacturers and don’t always trust the label. It would be great if all countries could also use their standards policies to these components as well, not just manufactured or finished goods. Release findings publicly and stick to an international measurement of grading. It is absolutely impossible for a class AB audio amplifier to push out 300W RMS/continuous per channel using just two 150W transistors per channel. It’s absolutely impossible for every transistor coming out of China carrying the Toshiba markings actually be a Toshiba. There is sometimes merit in paying more and forego that free lunch.
Further Reading: Elliott Sound Products
Electronic Components – Real Workhorses and Gems
Through the years there have been a number of electronic devices that have been used and abused in circuit making – hopefully some of the ones mentioned in our article will bring back fond memories. In the likelihood of some frustrated reader wanting to add in his or her own tirade under the comments section this list is by no means exhaustive – it’s from my own experiences working on consumer products through the years with one exception, the 555 timer chip which I have added because of the manufactured quantity each year. I did not find them that common in repair work but certainly if there is anyone out there whom hasn’t heard of this chip I’d love to hear about it. We exclude micro-controllers in this article as I felt they deserved a niche chapter in Parts-Ring.
There’s a lot being said about high end audio but how does one separate fact from fiction? Having spent the better part of two days browsing through websites which are supposedly either selling high end audio or are advocates of high end audio (critique) I’m rather more confused now than ever. To put it straight, if your CD or DVD sounds just like the original live recording then I’d say you have a masterpiece of an audio system. Unfortunately it’s not going to unless you have the master tape and the same audio equipment for reproduction as was used on stage. Of course, the same acoustics as well. I listened to a NAD system recently – the speakers were Mission. I don’t have the model details. It sounded awful – wrong position, wrong acoustics, wrong music. I know someone whom said the best system he had ever heard had ‘rags falling out of the loudspeakers’. I have no doubt these rags were being pulled out of a port and were acting as a damper of sorts. Not all speaker systems reproduce different genres of music the same. What sounds too bright to you sounds just right to the guy next door.
There are plenty of myths out there and the scope of this article is not to disprove them but rather to make you think before you splash out. Always pay the best you can afford – an expensive sound is not a myth. Just go to any live concert where a supergroup is playing and you can be rest assured that the sound system costs upwards of a few million U$. This is expensive sound. The Mission/NAD mix was expensive for a home user but not in our audiophile range – 2 000U$. The sexiest sound I have every heard was through a Wharfdale speaker system – yes, it was a disco unit. Guaranteed not for home use but Donna Summers sounded good. Continue reading “Try my Impeccable Audio”