Need advice on remote circuit

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Ok, where to start...
I'm working on my F5 and I want to be able to remote power the amps (yes my F5 are monoblocks) and since my A1.7 is on stand by for now I'm asking for advice.
My idea is to put a small 5VA transformer to supply power to a relay to control the main transformer (switched by the A1.7) and also be able to switch it on on the front panel.
Since I'm having to wait for the main switch to arrieve from HK it's not to urgente.



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Yes, a small auxiliary supply that is permanently ON while the unit is plugged in supplies power to all your auxiliary circuits.
These could be DC detect and trigger speaker protection, Soft start for main transformer, Remote start relay for main transformer, Remote ON/OFF via a long cable to a control unit.

My soft start has two mains relays and the 5VA transformer on the one PCB (63mmx79mm).
It has a 3way terminal block that goes via an overtemp switch and a remote low voltage ON/OFF switch. This passes the 12Vac from the 5VA This could be taken via a 2pin socket to a remotely located control board.
It has a 6way terminal block that takes in L+N and puts out aux L+N and the delayed L+N to the main transformer.
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Thanks guys
Yes my idea was a allways on small 5VA transformer (on order) with the relay on the primary side of the main 300VA transformer then running a control line to the preamp.
I still have to do some work on the chassis like some ventilation holes/slots on the bottom plate, need to sort some feet for them and some paint for the 2nd box (white one).
Couldn't find a switch to my liking on the local Maplin store so got some of that auction site and is going to be around 2 weeks till I get them.
Will let you guys know about my progress (with pictures)

Played a bit more today
Main plug with fuse in the back panel and speaker posts, made hole for control plug and pilot hole for the RCA.
Fixed the main transformer to the chassi.


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Ok, got transformer and main switch.
Can someone suggest a suitable relay the transformer is 160VA and capacitor bank is going to be 120 000uf (4x10000 + 4x22000uf).
My brother suggested a solid state one from Omron but is only rated at 2Amps at 240V.

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You can find traditional and solid state relays with very high current and voltage ratings.

A production F5 draws 180W of power from the wall which translates to 0.82A at 220V.
The power inlet and switch you have on your picture are most probably rated at 16A/250V as most AC inlets. So if you use a relay with at least that rating it won't be a bottleneck.
Your mains supply is limited to 13A continuous by the in plug BS1362 fuse.
That gives you upto 3.1kW from each plug top.
The IEC socket and plug are usually rated @ 10A and some are only 6A. Read what it says on the socket and on the plug.

The switch and/or relay should be rated for more than the maximum continuous current of the load and have a margin to meet transient current as well.
This transient current capability will probably be much more onerous than the continuous current.

I would be looking at 10A 250Vac switching. and maybe 16A 250vac.
I am building a preamp which will control a 16A/250VAC relay to power on and off a group of IEC outlets to supply the power and pre amps. My calculations put the continuous current consumption at a maximum of 2A/250V, which will still be confirmed with current measurent, but in any case still much lower than the rated current. This circuit has a resistor based soft start to avoid high trasients during startup, which are then switched off the circuit by a second relay.

So with a single button push I will power on and off all the equipments on the analog side off the stereo. Take a look , you might find some inspiration:

RelaiXedPassive -- Documentation
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Ok, now I'm officially confused...
The official F5 has a 3.15amp fuse for the main supply and we all know that the original power suplly has a 300VA transformer.
My F5 is a mono amp with a 160va transformer so I would think that a 1.6amp fuse should be enough and I understand that there is an inrush current that can be twice or triple the rated current but nowhere near the 10Amp you quote for the relay (I know more is better).
Anyway I found some relays capable of 40amp of inrush current and I'm going from there.
Now I need to design a board for it.

Thanks all, but the answer was under our (mine) nose.
Was looking for soft start/stand by projects on here and came across the A75 article/manual and there is was.
Triac operated switch with thermistor and spike supressor.
So another question...
Does anybody know the part number for the thermistor (TH1) and supressor (TZ1) on the A75 article/manual ?
I searched the part numbers on the manual but no luck.

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