230vac to 15vac

[fanaticz]

I have two speaker protection boards by JLester which needs 15VAC 1A each.

What do I need? I believe it's enough with a transformer that has 15VAC secondary, and no other components what so ever. But I ask because I'm not sure. No diodes , protection, anything?

 

[MarcelvdG]

You would probably need a fuse to ensure your house won't burn down if the transformer or the speaker protection board should develop a short circuit.

 

[fanaticz]

Haha, I figured, but thanks for reminding me. I was just curious if the transformer itself actually is enough. My ignorance feels like something else is missing.

 

[PRR]

To keep it simple: Yes, if you have 230VAC and the load wants 15VAC, you only need a 230VAC:15VAC transformer of appropriate size.

To also keep you safe, you want a fuse so a fault does not heat-up your line cord, set the carpet on fire, burn-up your house. And a box so your child/cat does not touch live wires. You may also want a switch. In some lands a commercial product must use a 2-pole switch. If the box is metal (plastic boxes should be Approved for hiding live wires, so not a cookie-tray) and you have a 3rd pin (PE, green wire) on your wall outlet, there should be a substantial bond from wall 3rd pin to bare metal on the box, so a loose wire will blow the fuse in the basement before anybody gets shocked.

 

[MAAC0]

Are there regulators on board ? Perhaps You will need not 15V AC, but slightly a couple of Volts more in order for them to work. For example a 7815 needs more 3V on the input.

 

[DF96]

He says the circuit needs 15V AC. If that is what the designer has asked for then he will already have taken account of what the DC arrangements are.

 

[Osvaldo de Banfield]

A transformer rated for 15VA (15V, 1A) will not burn any house still under shortcircuit conditions. The finest of the primary winding will act as a self fuse. In any case, external fusing and or a thermal cutout is recommended.

 

[CBS240]

Always provide a disconnect. I'm sure even the 15VAC transformer costs more than a fuse. Also, there are better smells than that provided by burnt insulation.