hey, hey! this is DIY and diy'ers are not limited to practices such as those seen on commercial offerings, we can do better....
AJT.
I showed a clear distinction between the MAIN ON/OFF switch and the resistor/NTC bypass relay CONTACTS.
Read what I wrote.
If you don't understand what I wrote, then you can ask for clarification, but don't rubbish my post because you don't understand the DIFFERENCE between the Bypass duty and the main ON/OFF duty.
I showed a clear distinction between the MAIN ON/OFF switch and the resistor/NTC bypass relay CONTACTS.
Read what I wrote.
If you don't understand what I wrote, then you can ask for clarification, but don't rubbish my post because you don't understand the DIFFERENCE between the Bypass duty and the main ON/OFF duty.
no problem....
between you and me, we build amps.....strange you have to react that way, i merely posted what i will do with "my amp"...every one is free to do as they wish with their own amps....
i wouldn't care what you do with your amp either....
This man has a short fuse and is often angry with those who do not understand well. Each is as is and can not change, it's good to be tolerant with the intolerant, although valuable as this guy. I hope someday improve forms and becomes more successful coexistence of this great forum knights scattered throughout the world and unfortunately were not born with the English language, yearn to learn and communicate with other beings who share the hobby.
AJT,
your post40 rubbished my comments.
posts 41 and 43, written independantly of me, recognised your abusive tactics.
I responded giving you the opportunity to ask for more information to help you to fully understand.
If on the other hand you already understand and you included a quote from my post as a belittling tactic then it appears you are the one resorting to abuse of other Members.
your post40 rubbished my comments.
posts 41 and 43, written independantly of me, recognised your abusive tactics.
I responded giving you the opportunity to ask for more information to help you to fully understand.
If on the other hand you already understand and you included a quote from my post as a belittling tactic then it appears you are the one resorting to abuse of other Members.
D
Deleted member 148505
I use 4pcs parallel 5W ceramic resistors for my softstart.
I tried to draw large current from my amp without turning on the softstart to simulate fault condition.
The resistors just gave an orange glow from the inside for a couple of seconds before failing. When they fail they just become an open circuit, no fire and no ashes on the outside. So I think they are safe to use
I tried to draw large current from my amp without turning on the softstart to simulate fault condition.
The resistors just gave an orange glow from the inside for a couple of seconds before failing. When they fail they just become an open circuit, no fire and no ashes on the outside. So I think they are safe to use
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not from you...thank you.....
i have been doing amps many years before i joined this forum....
I use 4pcs parallel 5W ceramic resistors for my softstart.
I tried to draw large current from my amp without turning on the softstart to simulate fault condition.
The resistors just gave an orange glow from the inside for a couple of seconds before failing. When they fail they just become an open circuit, no fire and no ashes on the outside. So I think they are safe to use
can you post the schematic?
D
Deleted member 148505
The circuit is a simple 555 power on delay.
Layout was designed such that if in case the resistors won't fail, and excessive heat was dissipated, there will be no or minimal chance that the mains wire or any parts of it will have a contact on the metal case.
20W total resistor rating would be enough for 100ms-200ms duration of large inrush current.
As I said earlier, when the resistor fails, it will go open circuit. The goal at fault condition is that the resistor(s) should fail to avoid excessive heat dissipation. Now when you use 50W resistor, it might not fail and will cause the solder that connects the mains wire to melt.
When the solder melts, the live mains wire might fall in the metal casing.
Layout was designed such that if in case the resistors won't fail, and excessive heat was dissipated, there will be no or minimal chance that the mains wire or any parts of it will have a contact on the metal case.
20W total resistor rating would be enough for 100ms-200ms duration of large inrush current.
As I said earlier, when the resistor fails, it will go open circuit. The goal at fault condition is that the resistor(s) should fail to avoid excessive heat dissipation. Now when you use 50W resistor, it might not fail and will cause the solder that connects the mains wire to melt.
When the solder melts, the live mains wire might fall in the metal casing.
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NTC = not such a good idea.
I use a series resistor shunted by a big relay. You can manually control the relay with a two position switch or use a timing circuit. I've done both.
If you use the former, be sure to use LARGE wattage power resistors, since you could, might just forget to flip the switch. It's been done.
The 10 ohm value is about right - you can test and figure it out empirically.
I used ~500,000ufd total at about 60vdc in my Symphony No.1 Amplifier.
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.5F thats a good feat.... I will be trying the same with prefersbly 20 ohms 50W resistors with relay and resistor in parallel
The resistance used varied somewhat with the specific amp and the time that the amp could possibly be in the "slow start" state.
With a manual switch that could (and has been) all day, unless you pay attention. So that was a 100watt resistor, iirc.
With the timed circuits, I used a long charge time, in the multiples of seconds, like 10-20 seconds (again iirc), so the resistors were smaller, I think those were probably 35 or 50 watt units. At the time I picked pile of them up surplus and inexpensively, and (again iirc) put two or three in series to get the requisite resistance, although that might have been in parallel for more power - again the final resistance was the key.
I determined the actual resistance empirically, watching the charge % and time it took to get there vs. the final current surge.
Keep in mind that one version of the amp used >4kva xfmrs and the "smaller" supply was >2kva so there is some inductive "pop" to contend with as well.
I'd not try to do an amp with this much capacitance today. Back then large "computer grade" electrolytics were reasonably priced and available. I did that much capacity with only 6 cans!
Today, I'd likely opt for getting some "fast" capacitance very near to the output devices as one method that I have heard is effective.
Ymmv.
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unfortunately it is not there....i emailed WJung asking permission to post article...
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