Hi Frans,
First of all, good luck with the progression of your design. How long does it take to deliver the chassis, once you've ordered them from the supplier you mentioned earlier?
Have you already decided which (design of a) soft-start module you're going to use to switch both of your 500 VA PSU transformers?
Gerald
Gerald,
I think I read on the suppliers site that it would take 3-5 days after payment. That would mean that the enclosure should arrive somewhere next week.
I ordered the LC-Audio soft start module.
Frans
I think I read on the suppliers site that it would take 3-5 days after payment. That would mean that the enclosure should arrive somewhere next week.
I ordered the LC-Audio soft start module.
Frans
Bruno Putzeys said:
What fuse should I use, then (for 2x500VA). The guys at Hypex thought about 6.4A, but they were not shure.
Frans
normally a toroid has a label stating what kind of fuse to use in series with the primary windings. At least, all of the toroids I've seen have that label ... 😉
Guys,
Our transformers are custom made and don't have this label. 😀
Frans if you don't have a softstartmodule you must use Slow Blow 6,3A. With a softstartmodule (from LC audio, perhaps), you can use a lower value of 4A.
Regards,
Jan-Peter
Our transformers are custom made and don't have this label. 😀
Frans if you don't have a softstartmodule you must use Slow Blow 6,3A. With a softstartmodule (from LC audio, perhaps), you can use a lower value of 4A.
Regards,
Jan-Peter
why dooes everybody insist on a special (expensive) softstart thing when you can just use an NTC ? about 1,30 eur in local shops for a big'un.
Frans,
The fuse is for one Transformer. A NTC has one big disavantage, to reduce the resistance it must be heated up........
Regards,
Jan-Peter
The fuse is for one Transformer. A NTC has one big disavantage, to reduce the resistance it must be heated up........
Regards,
Jan-Peter
matjans said:
As Jan-Peter says it needs to heat up. For a Class A amp this is not a problem and the resistans will decrease quickly and since current draw is fairly constant it will stay low. With these modules current draw is virtually zero at idle an hence the resistance is high and when the amp starts drawing current the NTC heats up a bit. Essentially you are modulating you power supply with the NTC...can't really see why you would try and screw up something that needs to be as good as possible...
right. didn't think of that. stupid me. 
there's a dutch saying that goes like this: 'kicking in open doors'.
Well, sometimes, pointing out the obvious isn't as useless as you'd think...
there's a dutch saying that goes like this: 'kicking in open doors'.
Well, sometimes, pointing out the obvious isn't as useless as you'd think...
"RFC" 😉
what would happen if i'd use an ntc with a high current rating at 25C (say 9A) and a low internal resistance?
Wouldn't this minimalise the effect the ntc has on the psu as a whole?
i can imagine that when using the ucd400's the effects on the psu could still be of concern but as it is i'm using ucd180's. Now this might be the wrong thread for it (sorry) but i have one question remaining.
when, if ever, would these modules require so much power that the ntc becomes the bottleneck? In other words, would the peak current required for refilling the caps during operation exceed 9A? If yes, when?
i'm trying to learn here!
what would happen if i'd use an ntc with a high current rating at 25C (say 9A) and a low internal resistance?
Wouldn't this minimalise the effect the ntc has on the psu as a whole?
i can imagine that when using the ucd400's the effects on the psu could still be of concern but as it is i'm using ucd180's. Now this might be the wrong thread for it (sorry) but i have one question remaining.
when, if ever, would these modules require so much power that the ntc becomes the bottleneck? In other words, would the peak current required for refilling the caps during operation exceed 9A? If yes, when?
i'm trying to learn here!
I don't know if you are aware of this circuit available here:
http://mitglied.lycos.de/Promitheus/delay_circuit_for_toroids.htm
A good DYI alternative of LCAudio softart.
http://mitglied.lycos.de/Promitheus/delay_circuit_for_toroids.htm
A good DYI alternative of LCAudio softart.
softstart
Somewhere I've seen an industrial relay with on-delay be used in a softstart circuit for audio. It is small, approved, more safe than a open PCB, more flexible, cheaper (~22Euro for a Finder 8A-type)...
Yes, I need to add a power resistor.
Are there additional serious disadvantages?
Regards, Timo
Somewhere I've seen an industrial relay with on-delay be used in a softstart circuit for audio. It is small, approved, more safe than a open PCB, more flexible, cheaper (~22Euro for a Finder 8A-type)...
Yes, I need to add a power resistor.
Are there additional serious disadvantages?
Regards, Timo
Hi Matjans,
The other problem with ntc's, other than the modulation of the main supply rail, is that even if the following circuit is drawing enough current to keep the part hot and therefore of low resistance that is power is turned off and back on the ntc doesn't have time to cool down and the transformer can in-rush again as if it were not there. Ok, the secondary capacitors may not have had time to discharge, but the toroid primary will still inrush. One way to solve this is to short out the ntc with a relay after a time delay so that it's influence does not effect the amp rails and it coold down again, ready for the next restart, but we are back to a more sophisticated circuit again.
Regards
Robin
The other problem with ntc's, other than the modulation of the main supply rail, is that even if the following circuit is drawing enough current to keep the part hot and therefore of low resistance that is power is turned off and back on the ntc doesn't have time to cool down and the transformer can in-rush again as if it were not there. Ok, the secondary capacitors may not have had time to discharge, but the toroid primary will still inrush. One way to solve this is to short out the ntc with a relay after a time delay so that it's influence does not effect the amp rails and it coold down again, ready for the next restart, but we are back to a more sophisticated circuit again.
Regards
Robin
LCAudio Power Supply and Soft Start Circuit
I have four UcD400's waiting to be built. While it's definitely not the most economical approach, it looks like the lcaudio Predator power supply and digital soft start kits are a good solution to the power supply for a stereo pair of UcD400's. Before I drop the cash, two questions:
1. Has anyone looked into replacing the 63V caps that come with the Predator PSU with 80V caps? Is there space on the board for this? Has anyone asked lcaudio whether it's possible to get an 80V 10,000uf cap instead of the supplied 63V caps?
2. The digital soft start module is advertised as "max. 10 amp". Does this mean that no more than 10 amps will be allowed to flow through the module? That it will go boom if you run more than 10 amps through it? Since the UcD400 has overcurrent protection that doesn't kick in until 15 amps, will this soft start unit limit the performance of the UCD module?
Ok, so, there were some subparts to each of my two questions...
Jan-Peter -- does Hypex offer soft-start modules? Power supply PCB's? (maybe since I asked the question, you'll be allowed to answer without breaking the "no soliciting" laws around here)
Thanks.
Brad
I have four UcD400's waiting to be built. While it's definitely not the most economical approach, it looks like the lcaudio Predator power supply and digital soft start kits are a good solution to the power supply for a stereo pair of UcD400's. Before I drop the cash, two questions:
1. Has anyone looked into replacing the 63V caps that come with the Predator PSU with 80V caps? Is there space on the board for this? Has anyone asked lcaudio whether it's possible to get an 80V 10,000uf cap instead of the supplied 63V caps?
2. The digital soft start module is advertised as "max. 10 amp". Does this mean that no more than 10 amps will be allowed to flow through the module? That it will go boom if you run more than 10 amps through it? Since the UcD400 has overcurrent protection that doesn't kick in until 15 amps, will this soft start unit limit the performance of the UCD module?
Ok, so, there were some subparts to each of my two questions...
Jan-Peter -- does Hypex offer soft-start modules? Power supply PCB's? (maybe since I asked the question, you'll be allowed to answer without breaking the "no soliciting" laws around here)
Thanks.
Brad
Re: softstart
I have an Elesta time module + 11-pin industrial relay + 100 ohms as soft start for my subwoofer. Works good but is maybe a bit expensive if you have to buy the parts (which I didn't have to 🙂 ) but a open pcb is equally safe if it is built in correctly.tiki said:
Re: LCAudio Power Supply and Soft Start Circuit
PS: You could also ask Lars Clausen yourself since he is a user here 🙂
If you have good quality caps and your voltage is around 60 volts there is no particular advantage to have 80 V caps. Dangerous voltage is probably over 70 volts.dc said:
I'll guess the relay in particular is rated 10 A maybe 16 A but this is for _breaking_ capacity. In Europe we have 10 A as max fuse rating for normal needs.dc said:
PS: You could also ask Lars Clausen yourself since he is a user here 🙂