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Author Topic: Controlling Amplifier Power through Arduino and Relay?  (Read 624 times)
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Hello All,
           I was hoping to be able to put something together to control the AC Power for an Amplifier but I'm having some trouble selecting a Relay that can handle the load...

The problem I'm having is unfortunately there is no information on how much current the amplifier draws. The only thing I've been able to find is a 5A/250VAC ceramic fuse just after the AC IN.

The Question/s
Does having a 5A/250V Fuse mean that under normal operating conditions, the current drawn by the Amplifier will never exceed 5A?

Would it be safe to use a Relay rated for 5A/250VAC or should I use a 10A relay be a better option?

Thanks guys for your help in advance.
Alex
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Hello All,
           I was hoping to be able to put something together to control the AC Power for an Amplifier but I'm having some trouble selecting a Relay that can handle the load...

The problem I'm having is unfortunately there is no information on how much current the amplifier draws. The only thing I've been able to find is a 5A/250VAC ceramic fuse just after the AC IN.

The Question/s
Does having a 5A/250V Fuse mean that under normal operating conditions, the current drawn by the Amplifier will never exceed 5A?

Yes, except fuses are pretty slow acting and in fact many specify 'slow blow' fuses that will allow short term current well above their steady state 'blow' rating. This allows for start-up surge current to charge up power supply filter caps.

Would it be safe to use a Relay rated for 5A/250VAC or should I use a 10A relay be a better option?

10 amps is the better choice and it's a very standard contact rating, plus one would always prefer the lower cost fuse to blow before the more expensive relay contacts. But there is that old engineering adage (black humor because it happens) about the final output transistors blowing open to protect the power supply fuse.

Lefty


Thanks guys for your help in advance.
Alex
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If its an audio amplifier you can estimate the power consumption from the size of heatsinks and the rated maximum output power.  There may be spec sheet for it somewhere on the web. 
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Wise words Lefty, I'll go with the 10A Relay. Cheers.

Thanks again,
Alex
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