Every toaster I have had have ALL been properly wired with 3core mains cable and all exposed conductive parts connected securely to PE.
I cannot see (even though I am NOT a trained Double Insulated Engineer) how a two wire Toaster could pass a Double Insulated standard !!!!!!
How much substandard equipment is being flooded onto the market by fraudsters trying to fleece you of your cash?
If there is such a concern, relying on the interconnect shield as a protective earth is dubious at best when you can simply add a PE to the appliance yourself in a safe way.
Welcome Ren,
Aim for 35VDC rails and you will get roughly 55 watts into 8 ohms.
25-0-25 VAC transformers will do nicely.
regards
Thanks Greg!
hmmm. I have 300VA traffo, (I think, searching online) but the output is
33.5-0-33.5VAC, when rectified I will get roughly 47Vdc per rail.. May I need to find a way to reduce the rectified output. Will it be sufficient for 4ch amp?
hmmm. I have 300VA traffo, (I think, searching online) but the output is
33.5-0-33.5VAC, when rectified I will get roughly 47Vdc per rail.. May I need to find a way to reduce the rectified output. Will it be sufficient for 4ch amp?
A 1u cap across the trafo side of the rectifiers may decrease your voltage. Sometimes a trafo resonance will boost voltage after the rectifiers. I have a trafo that went from 20V to 18V after I added a 1u cap. Your example seems to be a trafo designed to sag under load though, as the voltage difference is so large.
This question has been asked hundreds of time.
Simple answer: Buy the right transformer or look for a amplifier designed for 47V rails. 😀
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You and me are NOT allowed to modify a double insulated and certified piece of equipment by adding a PE.
The interconnect would only have to pass 100mA from Mains fault to your body to kill you.
Any interconnect that I am familiar with can easily pass that amount of fatal current.
The problem is that the downstream connection to PE must blow the fuse in the faulty equipment fast enough that users are not exposed to the shock risk. If that escape route has a resistance in it that may prevent the fuse blowing then you may be left with a LIVE chassis and the fuse NOT blown.
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haha, I have already thought that Greg but the budget is tight so I may have to modify this trafo.
I have a toroidal trafo (od = 115mm, id=65mm and h=55mm), salvaged from an old amplifier, I think ( I don't really know where it came from). Searching the internet from the size it has, I think this a 300VA transformer.
am I thinking correctly here? 😀
I have a toroidal trafo (od = 115mm, id=65mm and h=55mm), salvaged from an old amplifier, I think ( I don't really know where it came from). Searching the internet from the size it has, I think this a 300VA transformer.
am I thinking correctly here? 😀
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This amplifier design is an adaption/upgrade of an earlier design.
40 years ago when I was an 1st year apprentice I built one of those but being power mad young idiot I upped the voltage rails to screw a few more watts out of it. At the time I had never even heard the terms SOA (Safe Operating Area) or SOR (Safe Oerating Region). Did it work? Yes it did, untill the 1st party where I "cranked" it up a bit, at which time it quite literally went up in flames. It was very (briefly) spectacular.
Stick to the Rail Voltage recommendations fairly closely, +/- 2 or 3 volts you can get away with. +5V or more is building a time bomb.
Cheers,
Ian
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Okay, but what in a double insulated appliance ensures that the fault current flows through a fuse? What if the insulation failure occurs in a path without a fuse?
The fuse is at the point of entry.
If there is ANY failure that allows mains power to escape to Neutral or to Earth, then the Fuse will blow when it's rating is exceeded. It achieves this by Design.
The problem is that many double insulated audio gear have outputs and inputs. These connections can have cables attached. There is the problem !!!!
The mains can't escape while the double insulated is stand alone. There is no route.
Attach a cable and a child pokes that cable in his/her mouth and the escape route is established.
It's this extreme danger that forces the authorities to stipulate the design and testing to achieve the necessary safety for the Class11 product.
We cannot and must not interfere with the warranted product.
But we all plug them into our other audio gear.
Is that so? I've been seeing this amplifiers all around but never though it has toroids on it. So is it true that it is 300VA?
An externally hosted image should be here but it was not working when we last tested it.
Based on Hugh post of the conceptual circuit AKSA 55, here is my Schematics..
Comments? 😀
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C3 has to connect to the top of R13, not the bottom.
C3 is the -IN input. It is a Signal Input. It must connect to the Signal Return at the input socket.
Move L1 to the other side of the R11 tapping point. Add a damping resistor parallel to L1.
Reduce R14 a bit, maybe 300r or 270r.
R3 will almost certainly need to be trimmed to get the currents in the LTP balanced.
How can you measure the balance of these currents when you have no degeneration resistors fitted?
And please attach your pics.
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Perhaps when you look at one source "conceptual schematic" of the AKSA 55 (ESP P61) , you can see where the errors in adapting the schematic arise. You have to think here, what the term conceptual means and the significance of that ground symbol, rather than an earth symbol. It may not be a standard diagram for good reasons....
Here's a Ukranian site's archive of P61 which has been copied from Rod Elliott's now deleted P61 pages. You can see why he gets mad at guys who just rip and re-publish whatever interests them. As an archive now, it comes in handy, but obviously it's also easily misinterpreted: 55?? (????????????? 75??) ????????? ???????? - ????? - Radioland
Here's a Ukranian site's archive of P61 which has been copied from Rod Elliott's now deleted P61 pages. You can see why he gets mad at guys who just rip and re-publish whatever interests them. As an archive now, it comes in handy, but obviously it's also easily misinterpreted: 55?? (????????????? 75??) ????????? ???????? - ????? - Radioland
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The Ukranian schematic is also not quite correct, although everyone will recognize the similarities the real AKSA is slightly different.