I too am comparing the SMPS1200 to the SMPS400 for powering two Ucd400HG modules. I noticed that the SMPS1200 data sheet states that the DC error input is incompatable with the Ucd400HG and Ucd180HG modules. This puzzles me because Hypex apparently recommends this power supply for these modules.
I verified it with Hypex, too- the SMPS1200 will drive multiple modules but the DC error doesn't work.
I'm not *that* concerned with it because the DC error is most likely to happen when driving things hard, and I'm building with the intent of having lots of headroom. I guess I'll just cross my fingers.
It would have been simpler to use multiple SMPS400 supplies, but the chassis mounting (and fanless cooling) seems a bit easier with the SMPS1200.
I'm not *that* concerned with it because the DC error is most likely to happen when driving things hard, and I'm building with the intent of having lots of headroom. I guess I'll just cross my fingers.
It would have been simpler to use multiple SMPS400 supplies, but the chassis mounting (and fanless cooling) seems a bit easier with the SMPS1200.
I was afraid of this. I do think that a switch rated for 20-30A should be able to handle the momentary load of 74A, but it's better to be conservative.
Hypex psu I used have a standby mode via small dc supply, in my case 5v via cheap mobile phone charger. I am using nice and cheap vandal switch to turn amp on or off.
Hope it helps
Marko
Seems a good idea at first... but the PSU idle state draws 9W.
18W permanently wasted for nothing at all.
Standby mode and idle are not synonims, I am sure power draw in standby is less then 1 watt.
DC error could happen anytime. Though I am pretty sure the amp modules are AC coupled and will be protected from DC upstream.
Maybe you should think about a soft start module? Hypex sells one that just needs a push button switch. For the SMPS 1200 you'll need one for each smps.
Johan-Kr
Johan-Kr
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No,you are not. External small voltage DC supply is cheap, power switch rated for 30-50A is not.
Kind regards
Marko
It would make more sense to supply a small voltage to turn it on as is done in many other power amps.
You are right,
But a relay cost less than an good quality external supply, it draw zero watt, protect your amp from AC failures and don't wear components for nothing.
But for a relay you need external power supply as well, trust Hypex designers, they know their job.
You can rectify the AC directly and feed the relay coil with a resistor divider. (it works only with low currents)
Then put a switch on the rectifier and use the model you want thanks to the extremely low current consumption.
One relay, one rectifier and two resistors.
Straight off the mains, without isolation transformer inbetween, that is dangerous.
One mobile phone charger 5V, cost 2EUR, safe, cheap and reliable.
Kind regards
Marko
Wallplug adapters d'ont have isolation transformers... they are "straight off the mains" too.
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Wallplug adapters d'ont have isolation transformers... they are "straight off the mains" too.
Of course they are, but:
A.) they were made by proffessionals with some kind of safety standard
B.) they are encapsulated in plastic, which reduces the chance of touching mains
I saw your amplifier and it is obvious that you know what you are doing, but consider the possibilty that original poster is not so experienced and cannot make his own pcb for the circuit you recommended in a safe way.
Working directly with AC mains is dangerous.
We are polluting this thread, apologies to the OP, I am out.
Kind regards
Marko
Ok, i don't want to waste my time to explain ISO insulation classes and their field of applications here, and gives you headaches.
In this application the SMPS PCB is connected to the AC, the whole PCB is at 220V (in Europe🙂) and fixed to a full metalic case.
The AMPS plates are connected to the SMPS that is also connected to the AC.
😀 This is by far the worst case scenario, but your computer is also built like this and you are not dead.
This is a great security argument in favor of linear power supply, there is very robust galvanic isolation and All the PCBs are connected to safe voltage.
I'm still undecided about just using the 20A switch or using a relay with a 120V coil. Here's a link to such a relay: T92P7A22-120 TE Connectivity Potter & Brumfield Relays | Relays | DigiKey
It's rated for 30A, but I'm unable to find the rated surge current. Probably OK for 74A, right? Maybe at reduced longevity? I'll probably only cycle it once per day, so if it lasts 20,000 cycles instead of 100,000 I'm OK with that.
It's rated for 30A, but I'm unable to find the rated surge current. Probably OK for 74A, right? Maybe at reduced longevity? I'll probably only cycle it once per day, so if it lasts 20,000 cycles instead of 100,000 I'm OK with that.
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