EPE Magazine February 2018
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Hi,
here you can findit on the middle of the webpage (scroll down) as modification of the component list
EPE Magazine January 2018
BR
G
PS: created by the developer and author himself
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Now I've read it.
The first two articles use 45-0-45 as the transformer voltage. The third Silicon Chip article uses 40-0-40. Well, that clears up that little mystery. I suppose there is an errata for the first two articles somewhere, but I haven't found it.
Everyday Practical Electronics haven't published the third article yet.
Hi,
reading the articels is always helpful.
The first two articles use 45-0-45 as the transformer voltage. The third Silicon Chip article uses 40-0-40. Well, that clears up that little mystery. I suppose there is an errata for the first two articles somewhere, but I haven't found it.
Everyday Practical Electronics haven't published the third article yet.
For the SC200, why did SC change the O/P inductor orientation from vertical to horizontal? It also changed on the ULD as I recall.
Looking at the Right-Hand Rule and Cherry's paper on mutual induction distortion, I don't see how a B-field parallel to the PCB (plane) is better than perpendicular.
Looking at the Right-Hand Rule and Cherry's paper on mutual induction distortion, I don't see how a B-field parallel to the PCB (plane) is better than perpendicular.
Attachments
Transformer voltage rating
Yes, you are right about the voltage rating. Measured an open circuit output voltage of 27.5 VDC on a toroid transformer rated at 25 VDC. So the regulation is going to be close to 10% for that particular example.
It may be that the initial development was done with the higher rated 45-0-45 transformer and at a later time a switch was made to the lower voltage. I can't seem to find any errata in Silicon Chip mag.
I wonder how much better this amp will sound when compared to an ETI480 or SC480? They were good robust amps.
Yes, you are right about the voltage rating. Measured an open circuit output voltage of 27.5 VDC on a toroid transformer rated at 25 VDC. So the regulation is going to be close to 10% for that particular example.
It may be that the initial development was done with the higher rated 45-0-45 transformer and at a later time a switch was made to the lower voltage. I can't seem to find any errata in Silicon Chip mag.
I wonder how much better this amp will sound when compared to an ETI480 or SC480? They were good robust amps.
The AES paper was rewitten as an ETI article.
In that ETI article the fig3 PCB layout can be clearly seen.
It was posted here a few years back, but I don't know what Thread.
Having re-read the Cherry paper I now realise where my current thinking on local supply rail decoupling started from.
Cherry's and other articles appear occasionally in the DIY magazines and much can be learned from them.
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Having built the Elektor Q-Watt Power Amp.......
Let's get some comments in from constructors of this project....
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EPE here – I hope users won't mind if I drop in to say that a number of queries have come our way regarding the availability of the SC200 mains transformer and we are in touch with our counterparts at Silicon Chip about it. There’s no doubt that the SC200 is one of those challenging designs that use some pretty difficult esoteric components. One benefit EPE enjoys is that usually, any wrinkles or bugs have been ironed out by the time the design reaches our pages. Rest assured we will come back with latest news or suggestions direct from the designers themselves.
I personally handle the design and management of the EPE website and I’ll add more mods or comments when available. As some users here have pointed out, the best links are the monthly project pages on the EPE web site where I post any addendum or corrections for future reference.
We also run our legacy ‘Chat Zone’ in read-only mode. It is here where our legacy ‘Shop Talk’ feature contains component-buying news. Topics - :: EPE Chat Zone ?:: ?Radio Bygones Message Board ::
EPE also wishes to sincerely thank those forum users who are continuing to support us. Without newsstand sales or subscriptions there would be no home-spun hobby electronics magazine left in Britain. EPE particularly deplores copyright theft and piracy which are very damaging to small independent publishers like ourselves. Although we do take action including legal measures in the worst cases, it would cost us our entire turnover to police and nail down acts of piracy seen all around the web. So thank you again to those who encourage the legitimate and fair purchase of EPE.
I personally handle the design and management of the EPE website and I’ll add more mods or comments when available. As some users here have pointed out, the best links are the monthly project pages on the EPE web site where I post any addendum or corrections for future reference.
We also run our legacy ‘Chat Zone’ in read-only mode. It is here where our legacy ‘Shop Talk’ feature contains component-buying news. Topics - :: EPE Chat Zone ?:: ?Radio Bygones Message Board ::
EPE also wishes to sincerely thank those forum users who are continuing to support us. Without newsstand sales or subscriptions there would be no home-spun hobby electronics magazine left in Britain. EPE particularly deplores copyright theft and piracy which are very damaging to small independent publishers like ourselves. Although we do take action including legal measures in the worst cases, it would cost us our entire turnover to police and nail down acts of piracy seen all around the web. So thank you again to those who encourage the legitimate and fair purchase of EPE.
Old articles
We know that very old material from Everyday Electronics, Practical Electronics, EPE or (UK edition) ETI – (let's say 30 years+) pops up on the web which is unlikely to cause much of a problem provided it is not being monetised or re-sold. The principles of ‘fair use’ apply to using more recent material – ie small extracts are OK for discussions or reference purposes, as long as entire circuit diagrams, constructional projects or other copyrighted material aren’t republished without permission. If in doubt, we like to be asked and we never refuse permission for reasonable requests. Hope that helps!
Alan W / EPE
We know that very old material from Everyday Electronics, Practical Electronics, EPE or (UK edition) ETI – (let's say 30 years+) pops up on the web which is unlikely to cause much of a problem provided it is not being monetised or re-sold. The principles of ‘fair use’ apply to using more recent material – ie small extracts are OK for discussions or reference purposes, as long as entire circuit diagrams, constructional projects or other copyrighted material aren’t republished without permission. If in doubt, we like to be asked and we never refuse permission for reasonable requests. Hope that helps!
Alan W / EPE
SC200 mains transformer
In case it helps, we have today published an update regarding the choice of mains transformer for the SC200 amplifier. From the designer:
The prototype used an Altronics MC5540 but it seems that part code has inexplicably been discontinued. They have also discontinued their full amplifier kits which included that transformer.
While I could probably find an equivalent device, I suspect it would be too expensive. The easier solution is to use two transformers: one 300VA 40-0-40 transformer and a 20-30VA 15-0-15 transformer like Jaycar MT2086 or Altronics M4915B. The mains primaries of the two transformers should be wired in parallel.
Arguably this is superior to a single transformer since the 300VA transformer is then tasked with only supplying the power amplifiers, so it will be able to supply slightly more peak current. It should also make chassis layout and wiring easier.
I don't understand why Jaycar and Altronics have both discontinued their 40-0-40 transformers since they surely would have sold a few, given that people continue to build our amplifier designs.
Nicholas Vinen
Editor
For future reference updates for EPE projects are also preserved in our legacy forum at :: EPE Chat Zone ?:: ?Radio Bygones Message Board ::: Shop Talk
In case it helps, we have today published an update regarding the choice of mains transformer for the SC200 amplifier. From the designer:
The prototype used an Altronics MC5540 but it seems that part code has inexplicably been discontinued. They have also discontinued their full amplifier kits which included that transformer.
While I could probably find an equivalent device, I suspect it would be too expensive. The easier solution is to use two transformers: one 300VA 40-0-40 transformer and a 20-30VA 15-0-15 transformer like Jaycar MT2086 or Altronics M4915B. The mains primaries of the two transformers should be wired in parallel.
Arguably this is superior to a single transformer since the 300VA transformer is then tasked with only supplying the power amplifiers, so it will be able to supply slightly more peak current. It should also make chassis layout and wiring easier.
I don't understand why Jaycar and Altronics have both discontinued their 40-0-40 transformers since they surely would have sold a few, given that people continue to build our amplifier designs.
Nicholas Vinen
Editor
For future reference updates for EPE projects are also preserved in our legacy forum at :: EPE Chat Zone ?:: ?Radio Bygones Message Board ::: Shop Talk
Transformer for SC200
Thanks for this input. I think anyone intending to build this amplifier and who has questions about the amplifier transformer/power supply should wait for the March EPEMag or purchase the March 2017 Silicon chip magazine.
If you are only interested in powering the amplifier module you need to supply +/- 57VDC to the amplifier to get 135 watts average output. The supply voltage can be decreased down to +/- 42 VDC to give 75 watts average output. Some resistor changes are required in the SC200 for the lower power version.
Silicon Chip recommend a 300VA transformer (40-0-40 VAC) to power two amplifiers at 135 Watts output for typical domestic use.
The Silicon Chip amp PCBs look ok.
Thanks for this input. I think anyone intending to build this amplifier and who has questions about the amplifier transformer/power supply should wait for the March EPEMag or purchase the March 2017 Silicon chip magazine.
If you are only interested in powering the amplifier module you need to supply +/- 57VDC to the amplifier to get 135 watts average output. The supply voltage can be decreased down to +/- 42 VDC to give 75 watts average output. Some resistor changes are required in the SC200 for the lower power version.
Silicon Chip recommend a 300VA transformer (40-0-40 VAC) to power two amplifiers at 135 Watts output for typical domestic use.
The Silicon Chip amp PCBs look ok.
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