I have dozens of devices that plug into the wall that don't have fuses. Right now I'm using a Breeze Audio JC-2 clone as a headphone amp. IMO they did not use fake parts and it's a fairly nice product (now gone I think).
There is not a practical L size which would limit 50-60 hz enough so that a dead short/fault would not cause breaker to trip.
Lightning transient Tr = 8 uSec tyoically. It doesnt take much series L to knock that peak down to a lower level.
Its the Surge levels of >10 uSec to 1 Milli Sec which cause the most damage (more energy).
A clamp-on ferrite can do the job of blunting any lightning transient to a lower peak level. Also, some noise filtering benefit.
Shows that all three wires from power cord go thru CM core. Ground/green wire from power cord goes thru core also and then to chassis/gnd. Direct and no splices. This is UL approved (legal).
No need to do Whole House L .. just use this at the point where your audio system is plugged into/powered.
THx-RNMarsh
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Scott, IME everything that's legal ie big name commercial product will have a fuse of some sort and some where in the primary circuit.
IME everything that is transformer based does that does not have a user or technician replaceable fuse will have a primary winding series thermal fuse buried/concealed in usually the primary windings of such transformer, this is standard practice in transformer plug pack/wall wart supplies.
In modern SMPS stages, be it internal module/sub pcb or external plug pack/wall wart type there will still be a fuse of some sort (semiconductor fuse, fusible resistor, encapsulated fuse etc) in the primary circuit.
This Samsung Charger video is funny on multiple levels but shows Samsung product (UL) practice.
You mentioned ?, that you run without (bypassed ?) primary or secondary fuses in your amp, so except for thrift (or lack of availability/motivation/memory etc lol) what is your reason for defeating/bypassing these usual protection methods ?.
If it is Test Signals that said so, or if you popped a fuse, bridged it out because you didn't have a replacement to hand and never got around to replacing it, or you reckon such amp sounds better just say
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Yes, if it is a UL/VDE approved transformer, it will have a thermal fuse embedded.
Makes part non usable and not repairable. But safe from over heating and causing fire.
-RNM
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So, any transformer without embedded thermal fuse is not UL/VDE approved ?.
Yes, thermal fuse is ultimate fail safe....but not technician undefeatable, it has proven economical/practical to replace such thermal fuses as a servicing procedure in certain cases.
Dan.
I should do the experiment to verify that my house earth electrode is good enough to cause trip of the 30mA RCD breakers.....all the circuits are RCD protected but I am not certain that RCDs are fail safe.
AFAIK RCDs rely on pulse of coil current to cause disconnect....ie inherently non fail safe.
Yes and Transorbs etc to limit energies
Yeah, and nothing protects against a direct hit ( ie plasma connection to the ionosphere).
Yes.
As should be.
True.......but.....lol.
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This is one of my customers for whom I make isolation amplifiers and measuring systems with optical fibre signal transmission.
Home - EGU HV LABORATORY a.s. Czech Republic
I have to cry when I read some opinions on current surge waves and protection against them, here.
Home - EGU HV LABORATORY a.s. Czech Republic
I have to cry when I read some opinions on current surge waves and protection against them, here.
This depends on the context, entirely. As far as engineering is concerned, you are wrong..........although all great engineering is teamwork these days, but in the end: I prefer to drive over a bridge designed by a competent psychopath than over one that came out of a process where people with mediocre skills and lacking technical rigour were all about being agreeable.
What experiment is that? The current flowing through you to Earth should trip a RCD.
RCD/GFI type breakers do not need ground to operate. They sense an imbalance of current between 2 wires and trip. It is assumed that if more current is flowing in one side of the circuit than the other, it must be going somewhere it should not be. You, for example.
The current could be flowing somewhere other than to the ground. The differential breaker does not know or care, it just trips.
The current could be flowing somewhere other than to the ground. The differential breaker does not know or care, it just trips.
I prefer to exchange daily friendly signs with the seaman who takes me across the river, or even to stay on this side of the bank, than to be massacred by your psychopath while crossing his perfectly designed bridge which will survive me.
Science sans conscience n'est que ruine de l'âme. ©Rabelais
Nobody, generally speaking, is especially fond of being slaughtered on bridges, but that is besides the point. Rabelais is a great tautologist.
While almost all modern low power products have a fused SMPS primary. There were decades of low powered products that didn't have fuses. For instance incandescent lamps & lights. Some had very small diameter line cords and the cords were in effect the fusible element.
I did misspeak the outside the case (line/safety) fuses are always there it was just the internal ones, time to talk about something else.
Here's a new topic. Does anyone have any leads on a schematic for a Spectral DMA-180 amplifier? A friend has one that cycles in and out of protection, drawing too little current on the defective channel but without large DC offset. I've looked at it but can't get very far with its potted subcomponents and complexity. All the output unObtainium Hitachi MOSFETs mercifully seem to have survived. Comparing channels with a curve tracer finds nothing. It's rare that I can't fix just about anything audio, so there's a lot of ego on the line.
I know this isn't a John Curl design, but it's thread family. Much gratitude and props for any help.
Much thanks, as always,
Chris
I know this isn't a John Curl design, but it's thread family. Much gratitude and props for any help.
Much thanks, as always,
Chris
Isn't that Demian's design, I'm sure he can help if so? I'm divesting a lot of old stuff and have several Hitachi MOSFET pairs from Hafler amps, you are welcome to them if they help no charge at all.
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I'm not sure how much I can help but its a direct descendant of my original design. PM me with more details and I'll help as I can. Having touched it you realize that Spectral with treat it as "unclean" and may refuse to repair.
Much thanks, and I'll PM you tomorrow. My touch is holy; it's still a virgin to even my own extremely strict standards. I've been very conservative, not removing anything from the circuit boards, and only observing with V-I curve tracer. My friend had first sent it to the factory, but they (and this is all second hand, through my friend, who's a real audiophile) recommended a multiple-$K replacement of both channels, yada, yada.
I can't say that I would fault the factory for their position. You're complaining that your Ferrari is difficult and expensive to repair? Really? Frickin buy a Honda.
Much thanks, as always, and I just saw a video you made at Burning Amp - very excellent,
Chris
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