[Kanaris]

I put together a solid state relay (SSR) to control my proamp.I am controlling the trigger part by a 10 volt dc transformer which is hooked up to a 120v wireless transmitter...


My question is are pro amps considered an inductive load or a resistive load..dumb question but I am not sure..If it's an inductive load I will need to modify my relay a bit..by adding a diode to the load part. Any help will be appreciated.

 

[PassingInterest]

If you have a large inrush current at startup, then it is not a resistive load.

 

[Speedskater]

Is your S.S. Relay rated to switch high current AC loads?

The turn-on inrush current may be a lot higher than the amps fuse rating. Fuses tolerate short high current peaks much better than S.S. Relays.


"a 10 volt dc transformer" is an oxymoron.

 

[Kanaris]

The SSR is rated for 40 amps...



It's not the trigger part I am worried about...


Where's Thylanter when one needs him?

 

[Speedskater]

Don't know how a diode could be connected to an AC load!

With a DC load the diode is installed backwards (so that it's not doing anything) then when the inductive field collapses (at turn-off) the diode shorts the reverse current across the relay.

 

[Kanaris]

So maybe I don't need one..since it's an ac load...


Check this out...
SSR HOOKUP

 

[mjg100]

I had problems when using solid state relays. I switched over to a mechanical relay and have it switching two pro amps. Getting ready to make another triggered switch for a third pro amp.

 

[Kanaris]

Mechanical relays can sometimes introduce 'hum' in the audio chain if their contacts get slightly pitted.

 

[thylantyr]

SSRs will fail if you overcurrent them or if you feed them high

voltage like "kickbacks" from an inductive load. I don't expect the amplifiers

to provide these kickback voltages that would damage the SSR.


Good amplifiers should have some form of inrush current protection, so

I'd bet these bare bones SSRs should work ok.


If you know you have overcurrent and/or kickback voltage problems

from the load, then what you would do is add more circuits to your

SSR design to compensate. You could add the MOV (metal oxide varistor),

the device found in the common surge protector outlets to your design.

You could design a soft start circuit for your amplifier.


Since you have this, hook it up and run with it bare bones. If you have SSR failures, then you'd have to redesign it. If this is too much drama, consider

the old fashion electromechanical relays.

 

[thylantyr]



Quote:
Originally Posted by Kanaris /forum/post/18231741


Mechanical relays can sometimes introduce 'hum' in the audio chain if their contacts get slightly pitted.

You can over-engineer the mechanical relay design. Instead of using

a single pole single throw to switch the AC line, you can use a double

pole single throw and parallel the contacts.


Also choose your relay contact wisely.
http://relays.tycoelectronics.com/ap...fs/13c3236.pdf


I saw an interesting relay for speaker switching, it used the tungsten

contacts to absorb the high voltage kickbacks when contact is made

or broken, but there was a secondary contact with gold that shorted

out the tungsten for good oxide free contact.


Tungsten contact makes first, then the gold one afterwards. To turn it off,

gold disconnects first, then tungsten last.

 

[Kanaris]

Thanks Thy, I tried it on my 1.5 hp dust collection motor.. and it worked fine.I had the motor on for about 15 minutes... it didn't even get warm.


Ps... it sort of has a soft on/off to it.

 

[mjg100]



Quote:
Originally Posted by Kanaris /forum/post/18231872


Thanks Thy, I tried it on my 1.5 hp dust collection motor.. and it worked fine.I had the motor on for about 15 minutes... it didn't even get warm.


Ps... it sort of has a soft on/off to it.

Mine worked for several months before it messed up. It fused in the on position. The electromechanical relay works fine with no added hum.