Speaker Protection & Soft Start_Ucd

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thomasfw said:
Anyone know that when install UcD 400 :

a) Speaker Protection is needed ?

b) "Soft Start" is must ? What is the alt. way ?
Can I use a CL-60 replace it ?


Thanks ! :smash:


a) That's a gamble that's your call to make, ideally it would always be employed, many people don't or haven't yet with them. Possibly one good reason for using the Hypex supplies if you are unable to make your own, but a simple fuse can also do the trick in a pinch.

B) You wouldnt' seriously put a thermistor in series with the output would you? They're less than ideal in series with the primary as a soft start because under normal operation they're too efficient to keep them warm, so you'd have to use a PTC in conjuction with it, but that won't save you if the mains drops out for a few seconds.

I've been using a 100W bulb in series with the mains to take care of surge current, bypassed by a switch.

Soft start circuits aren't that difficult though. There's also a number of them on the market that should work fine already.
 
For a simple soft start circuit I just got a 24VDC actuated relay and connected the coil leads to the +12 and -12 volt UcD power supply output. I also connected a 25 ohm power resistor across the N.O. relay contacts and in series with the transformer. When the supply voltage comes up it energizes the relay, bypassing the resistor. I haven't made any measurements to check the change in the current peak but the house lights don't dim during power up like before.
 
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