How to power on amps with no on/off switch?

Yes, yes we are and that's the reason I'm not going to ask the previous poster about "stored electrical energy in the transformer" :crazy:

Surely you know about stored energy in a inductor, which is what a transformer is. It is related to the need for a snubber across a switch.

The energy stored in the magnetic field of an inductor (or the inductance of a transformer) can be expressed as. W = 1/2 L I2 (1). where. W = energy stored (joules, J). L = inductance (henrys, H).

This is the principle that allows the ignition coil on a gasoline powered engine to work.

I used stored electrical energy, while not necessarily the most precise, it gives a simple example of the need for a snubber across a switch, it keeps everything in terms of electricity.

When the magnetic field collapses, the stored magnetic energy is converted into electrical energy and we are back to the need for snubber across the switch.
 
Yea, stored electrical energy might not have been the best way to phrase it.
I'm still surprised at how you came up with the 60V secondary. Even considering this is a MOSFET amp and taking into account the power supply droop, rectifier loss, etc...
60V x 1.414 = 84.84V too high, or at 60V C.T. 42.42V too low. I'm sure you also know the voltage/ current relationshp, one following the other in both inductors and capacitors. Your base the 100A inrush current on everything happening at that 0.01 second moment. Theory is one thing, but reality is another. If you need to be the expert on electronic theory, fine. I couldn't care less.
 
If the wall type switch is mounted in a separate DIY enclosure there is not problem, but I would have to look at the NEC for a switch installed in a wall and local codes may be more strict, I just do not remember what the NEC says about this (I know, I am old, broken down, not healthy and on medications)...

For those that want to DIY there own, there are switches in various formats (rocker, toggle and so on) that are rated for high inrush current. See the picture below.

This is just one example, there are higher rated switches available.

View attachment 1279879

Yes, wall type switch in a DIY enclosure along side some edison receptacles.
 
Yes, wall type switch in a DIY enclosure along side some edison receptacles.

It will work without a snubber, but for reasons that I have already posted it is not necessarily a bad idea to include a safety rated snubber across the switch terminals. It will reduce arcing at the switch contacts when the switch is operated and will reduce the possibility of unwanted electrical noise induced by the switch bounce induced arcing which can be fairly substantial in your situation.
 
i prefer the idea of sequential power ups as posted earlier .. it removes lots of doubts mentioned and is easy to use ..switch the one on that starts the sequence then no doubts . i used one for a few years until it went bad ..now i have to remember to use the switches .
 
With over 30A per amp at turn on, those 5A fuses would pop even though they are slow blow.

BTW, where did you get this information? I guess that you know more about fuses than Littelfuse and other fuse manufacturers such as Eaton Bussman.

It is not theory, it is common knowledge in the world of fuses. It is how engineers choose fuses for various applications. It is real world numbers not just theory.

You are picking on my choice of 60 volt secondary for each rail voltage after I have already corrected it and given an example of a secondary voltage that would give about 60 volts on each capacitor (for plus and minus rails).
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I'm still surprised at how you came up with the 60V secondary.

I will tell you how I came up with it. I entered the voltage that I wanted to get on the filter capacitors in the calculator as the transformer primary voltage and I corrected it in the same post.

Your base the 100A inrush current on everything happening at that 0.01 second moment.

It is not everything happening at 0.01 seconds, this is how long the fuse in my example will take to clear or blow when presented with 100 amps of current. Note that after the first peak of the sine (positive or negative) the current goes down.

From Littelfuse's chart it is clear that a 5 amp slow blow fuse will hold for about 250 milliseconds at 30 amps before blowing, but remember that by this time the surge current will have dropped well below 30 amps because this will represent about 15 complete cycles of the AC mains waveform which is about 250 milliseconds.


Note the current by only 80 milliseconds and it could be even less, let alone 250 milliseconds. Again, although my numbers are just ball park numbers for example from a distance, it is very easy to see what happens with a 5 amp slow blow fuse.

upload_2018-9-12_18-55-9.png

The fuse numbers are not my numbers, they are numbers from the fuse manufacture. And my representation of surge current may not be spot on, but it is definitely in the ball park.
 
i guess mixing electronic engineers with electrical engineers is never going to work ? .. i have many arguments that lead to nothing with my long time electrical engineer .. we sometimes both learn from each other . matter of fact he is asking me to do his job as he recently got a shock .. sorry for ranting. i think we should get on track with the original question .
 
i think we should get on track with the original question .

I agree.

Although somewhat long, my posts speak to switch ratings and the need for snubbers for the most part. But my OCDness causes me to speak up when I see incorrect information posted, with reference to my posts, such as the surge current handling of fuses.

Then I was told that the information that I posted from a major fuse maker is just theory when it is actually real world information that is used by engineers on a daily basis.

There are over 700 hits on this thread and it is likely that at least some of them will appreciate the correct information about surge current in linear power supplies, fuse ratings and switches.

I have already admitted that I made a mistake in one of my examples.
 
how can the op power on his amps in the easiest fashion ?
With switched outlets. There are numerous smart strips that can sense current on one outlet, and switch others on at that time, or some that are triggered by low or line voltages. There are some that use wireless to be controlled by your mobile device. I use one to power on my amp in my HT system. See here;

https://www.adafruit.com/product/2935?gclid=EAIaIQobChMI84Kwh-W23QIVkWF-Ch2d3w3sEAQYBSABEgLvNPD_BwE
 
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how can the op power on his amps in the easiest fashion ?

As you posted previously, I am a big fan of sequential switching of gear. There is plug and play hardware (a fair amount) for this as previously mentioned.

For none sequential switching of gear with factory made hardware, there are quality outlet strips with high surge current rated switches and the correct safety snubber across the switch contacts.

On the DIY front as the OP is doing, it is as simple as using the correctly rated switch with the correct safety snubber across the switch contacts in the desired enclosure with the desired outlets. Of course one needs to pay attention to the correct wiring in terms of hot, neutral and ground connections.

Some of the high end devices (outlet strips and sequential switchers may have additional noise filtering (RFI/EMI) which some feel may restrict the sound quality. For example it is not uncommon for the stated rule of thumb to be, amplifiers should not be plugged into anything other than directly to the AC mains outlet.

It is just about this simple in basic terms.
 
It will work without a snubber, but for reasons that I have already posted it is not necessarily a bad idea to include a safety rated snubber across the switch terminals. It will reduce arcing at the switch contacts when the switch is operated and will reduce the possibility of unwanted electrical noise induced by the switch bounce induced arcing which can be fairly substantial in your situation.
So the kind of switch I have in mind has set-screws for hot in and a hot out. Heavy duty wall switch used for electric motors.

That said, how would the snubber install?

If I have nothing to loose and everything to gain, then I will strongly consider it.
 
So the kind of switch I have in mind has set-screws for hot in and a hot out. Heavy duty wall switch used for electric motors.

That said, how would the snubber install?

If I have nothing to loose and everything to gain, then I will strongly consider it.
We used NTC devices in all of our amps at Altec. Especially those that were current monsters like kilowatt+ 9446's and Electrovoice's EV-7600's. It goes in series with line. They're relatively inexpensive, and they provide excellent performance, and are UL approved. Use the MegaSurge line.
 
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In terms of a safety rated switch snubber, it would be wired across hot out and neutral at the switch or it could be wired across the hot and neutral on the outlet. With my ODCness, I prefer to have it as close to the switch as possible in high surge current applications.

Going up a step, the correct safety capacitors can be uses for RFI filtering if desired. They likely will not hurt anything and might in certain situations help eliminate unwanted electrical noise. There application is different than a switch snubber.

As previously mentioned there are series connected devices that will limit the turn on surge current, again a different application than a switch snubber. And again there are those that do not want to add anything in series with the AC mains or internal power supply that might constrict the sound quality. I take no sides in this discussion. It can be like discussions about interconnects, power cords and speaker cables.

Of course there are any number of soft, step start circuits in some of the monster amplifiers.
 
In terms of a snubber, it would be wired across hot out and neutral at the switch or it could be wired across the hot and neutral on the outlet. With my ODCness, I prefer to have it as close to the switch as possible in high surge current applications.

Going up a step, the correct safety capacitors can be uses for RFI filtering if desired. They likely will not hurt anything and might in certain situations help eliminate unwanted electrical noise. There application is different than a switch snubber.

As previously mentioned there are series connected devices that will limit the turn on surge current, again a different application than a switch snubber. And again there are those that do not want to add anything in series with the AC mains or internal power supply that might constrict the sound quality. I take no sides in this discussion. It can be like discussions about interconnects, power cords and speaker cables.
AC is AC. If you add noise, you have to filter it out. If you restrict current, then what ever you have inserted is improperly rated for the load of the device. If you overload the circuit you run the risk of fire. Choose wisely.
 
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