Bobken said:
Hmmm... Everyone can misread. For example, when I wrote that I would suspect a RIAA corrector, I did not mean your own nice design of the corrector producing high level of high frequency distortions... Sorry my friend for your misreading...
myhrrhleine said:
I once put additional 6,800 uF caps after fuses. As the result, when power amp's output was shorted I got an electrolytic cap blown up by a discharge current.
zinsula said:OT:
I worked in a military light truck project many years ago. We had trouble passing the EMP test. This electromagnetic pulse induced such high currents in the inductive engine speed/crankshaft position sensor (used by the engine ecu) that the ignition module was destroyed each time we tested. No VDR, shielding etc. cured this. We measured 100eds of ampere induced!
A transzorb in parallel to the sensor near the ECU solved the problem, and only a transzorb diode withstood several NEMP pulses.
After the pulse, the engine still stopped but could be restarted.
Since then, I never forgot what a transzorb diode is capable of.
NB, my Junghans radio controlled watch passed away at the first pulse
I have long wondered how you create an EMP without a nuclear explosion? It may have its uses to, say, rid oneself of an annoying neighbor's TV.
syn08,
your ponderings suggest some measure of naiveness. Nothing (and nobody) is perfect in any sense.
The impact of dielectrics appears clearly when studying capacitors. The dielectric materials decisively set the properties bringing about huge differences and limitations.
your ponderings suggest some measure of naiveness. Nothing (and nobody) is perfect in any sense.
The impact of dielectrics appears clearly when studying capacitors. The dielectric materials decisively set the properties bringing about huge differences and limitations.
Lumba Ogir said:
Yes, I am naive and thank you for the lesson on dielectric properties. Allow me return the favor and suggest reading this humble work on polar dielectrics electrical properties: J. Appl. Phys. 73, 824 (1993)
Sigurd Ruschkow said:
Sigurd.
I am not the golden ear type.
You will know this, if you have read only a few posts of mine.
So, when I prefer air insulated 'board' and wirings it has absolutely Nooooothiiiing to do with any sounds.
It is more about the strive for the ultimate electrical quality.
And this is well in line with the Blowtorch CTC amplifier we are examining together with one of the CTC designers!
Practicality. Convinience. I couldnt agree more.
And teflon boards or whatever exotic PCB Plastic Circuit Boards you think you can afford to buy can not be very far from hard wireing approach.
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🙂 John Curl 🙂
1. What material you use in Blowtorch etched Plastic Circuit Boards?
2. What is the fusing or cricuit protection used in one Blowtorch?
3. What is the transformer used in Blowtorch power?
4. EI or toroid or whatever?
In post 7609 there's a pic of the inside of the Blowtorch... really sweet looking wire in there! 😀 😉
Anyhow, the Transzorb is really excellent in an application where there are some Mosfets working with significant voltage and current in a 3.8mHz application, actually a Class E ham design. They seem to protect the Mosfets and make them virtually bulletproof!
My understanding of MOVs is that they are very good, but once they take a "hit" they may not ever actually work properly again. And, there is virtually no way to know if they have taken that hit and have died. This understanding I seem to recall comes from a slick patent on transient supression for AC mains, or else the website that pertains to the actual commercial product (they don't use MOVs)... Some folks have separately (not that source) suggested that using an MOV and a Transzorb together neatly solves that problem and others... about the efficacy of this I don't know, but anecdotally it has been told to me. Ymmv.
Now, how does one go about fusing an amplifier that can deliver say 1,000 watts into 8 ohms and has output capability down to 1ohm?? 🙄
_-_-bear
Anyhow, the Transzorb is really excellent in an application where there are some Mosfets working with significant voltage and current in a 3.8mHz application, actually a Class E ham design. They seem to protect the Mosfets and make them virtually bulletproof!
My understanding of MOVs is that they are very good, but once they take a "hit" they may not ever actually work properly again. And, there is virtually no way to know if they have taken that hit and have died. This understanding I seem to recall comes from a slick patent on transient supression for AC mains, or else the website that pertains to the actual commercial product (they don't use MOVs)... Some folks have separately (not that source) suggested that using an MOV and a Transzorb together neatly solves that problem and others... about the efficacy of this I don't know, but anecdotally it has been told to me. Ymmv.
Now, how does one go about fusing an amplifier that can deliver say 1,000 watts into 8 ohms and has output capability down to 1ohm?? 🙄
_-_-bear
>Now, how does one go about fusing
>an amplifier that can deliver say 1,000
>watts into 8 ohms and has output
>capability down to 1ohm??
" Slo-Blo " fuses
>an amplifier that can deliver say 1,000
>watts into 8 ohms and has output
>capability down to 1ohm??
" Slo-Blo " fuses
bear said:
Like any electrical system of similar input power and current, I would say. Take a good fused or non-fused circuit breaker of appropriate switching capability. Merlin Gerin and many others produce them.
bear said:
Its very hard to "hit" a modern MOV with enough surge energy to damage it, but a few seconds of excess AC or DC can cook one quickly. The instantaneous power capacity is high but the continuous dissipation is only a few watts max. MOV's don't degrade gently they are either fine or a charred ruin. They aren't very precise as Zeners but the on resistance is effectively .1 Ohm, which is why they work for surges.
Metal Oxide Varistors have a very soft "knee". As a result small currents flow long before the threshold voltage is reached. They are constructed of a very granular material squeezed into a final shape. They are usually rated in VAC (not peak).
I was taught that the large numbers of multiple junctions were noise sources, so I have always avoided them in situations where this noise could get into the signal path.
I also understand that each significant surge hit will gradually change the threshold as well as soften the knee. After a number of surges they draw enough current below the rated threshold voltage that self heating will damage them further.
I have never confirmed these teachings, they made sense and much of the data came from MOV manufacturers. (I designed telephony circuits where lightning protection was standard and required. Probably a million of my circuits are in daily use)
A "transorb" on the other hand is merely a pulse rated zener, they are very fast and have predictable and stable threshold values. The most common rating is 1.5KW (for about 1/2 millisecond) so they are far more delicate than a MOV. They are usually rated in VDC (peak) although back to back models for AC are available. For these devices, leakage currents are tiny, so below the threshold voltage they are electrically quiet. Transorbs usually make the most sense on the secondary side of transformers or power supplies. The lower voltage models will safely handle up to 200 Amps.
There is a third kind of device, an SCR or Triac triggered by a high voltage zener. Once triggered they clamp at about1.5 to 3 V so self heating even at significant current is not much of a problem They have a major drawback; once triggered voltage must be removed to "reset" them (actually current must be lowered below a hold threshold). They are a good way to guarantee that a fuse ahead of them will blow in a overvoltage fault condition.
Mostly obsolete are gas tubes. Think of a neon light bulb designed for hundreds of amps. No bigger than an MOV They are all but indestructible, sort of expensive and also suffer from a need to have a break in current or voltage to reset them. I think models are available in the general range of 100 to 350 Volts.
I was taught that the large numbers of multiple junctions were noise sources, so I have always avoided them in situations where this noise could get into the signal path.
I also understand that each significant surge hit will gradually change the threshold as well as soften the knee. After a number of surges they draw enough current below the rated threshold voltage that self heating will damage them further.
I have never confirmed these teachings, they made sense and much of the data came from MOV manufacturers. (I designed telephony circuits where lightning protection was standard and required. Probably a million of my circuits are in daily use)
A "transorb" on the other hand is merely a pulse rated zener, they are very fast and have predictable and stable threshold values. The most common rating is 1.5KW (for about 1/2 millisecond) so they are far more delicate than a MOV. They are usually rated in VDC (peak) although back to back models for AC are available. For these devices, leakage currents are tiny, so below the threshold voltage they are electrically quiet. Transorbs usually make the most sense on the secondary side of transformers or power supplies. The lower voltage models will safely handle up to 200 Amps.
There is a third kind of device, an SCR or Triac triggered by a high voltage zener. Once triggered they clamp at about1.5 to 3 V so self heating even at significant current is not much of a problem They have a major drawback; once triggered voltage must be removed to "reset" them (actually current must be lowered below a hold threshold). They are a good way to guarantee that a fuse ahead of them will blow in a overvoltage fault condition.
Mostly obsolete are gas tubes. Think of a neon light bulb designed for hundreds of amps. No bigger than an MOV They are all but indestructible, sort of expensive and also suffer from a need to have a break in current or voltage to reset them. I think models are available in the general range of 100 to 350 Volts.
Bear said:
1000W into 8ohms implies about 3000W into 2r0 and survives a 1r0 short term load (ten seconds or so).
This would use a 3kVA to 5kVA transformer to enable that 3000W output capability.
Soft start on 220/240Vac using 20r (four 20r 5W ww in series parallel) for 200mS and fuse primary @ T16A.
This cannot be supplied by a BS1363 Plug Top. Some more appropriate cable connector is required.
The secondary side would be slow start using Power Thermistor for 2S and fused after the smoothing caps with F25A (if such exists) or an A type MCB or Bobken's ETA suggestion.
it's all down to arithmetic.
Re: Surge protection
To protect against lightning and similar types of dangers,
we at the Power Division used (company does not exist anymore) Surge Arresters. These are gas filled tubes made for this purpose.
I have not tested these in audio circuitry though.
CP Clare Corp. is one manufacture of these devices.
Sigurd
To protect against lightning and similar types of dangers,
we at the Power Division used (company does not exist anymore) Surge Arresters. These are gas filled tubes made for this purpose.
I have not tested these in audio circuitry though.
CP Clare Corp. is one manufacture of these devices.
Sigurd
1audio said:
Re: Re: Surge protection
Leakage currents in gas tubes are tiny so very little energy is available to make noise, they should be fine in audio circuits and were once used in vast quantities for telephone tip/ring protection. Telephony circuits have better maximum noise requierements than you might at first suspect (about 90db below 1 milliwatt max at the tip/ring demarcation). While this isn't audiophile grade, I don't think any real part of that noise came from the gas tubes.
Hi Sigurd.Sigurd Ruschkow said:
Leakage currents in gas tubes are tiny so very little energy is available to make noise, they should be fine in audio circuits and were once used in vast quantities for telephone tip/ring protection. Telephony circuits have better maximum noise requierements than you might at first suspect (about 90db below 1 milliwatt max at the tip/ring demarcation). While this isn't audiophile grade, I don't think any real part of that noise came from the gas tubes.
Re: Re: Re: Surge protection
Hi Herman,
I think that they will be fine for audio, too.
Looking at the datasheet for the 240VAC version of the gas tube, I see that max V before it will start doing its job is impulse 800VAC, which to me means that one needs another device to take care of the lower voltage transients, too.
Thus,
in my next project (several ongoing) I will use BOTH my standard transorb (1500W) and a gas tube.
Sigurd
Hi Herman,
I think that they will be fine for audio, too.
Looking at the datasheet for the 240VAC version of the gas tube, I see that max V before it will start doing its job is impulse 800VAC, which to me means that one needs another device to take care of the lower voltage transients, too.
Thus,
in my next project (several ongoing) I will use BOTH my standard transorb (1500W) and a gas tube.
Sigurd
hermanv said:
1audio said:
Hi Demian, my ATR11 catalog says the 8x limit applies to C/Bs rated less than 6A.
1audio said:
Hi Demian. EMP test generators are huge pieces of equipment, run on 480V 3-phase power. Test pulse is injected into the wiring by a huge coupler, like a current transformer. This was how we ran the preliminary qual tests. The final qualification was run at White Sands test facility where the used a nuclear reactor to bombard the equipment with real neutrons, just like a nuclear detonation. I suspect this would not be available at Radio Shack.
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