6g2 Brownface Princeton build

[MikeC]

Would this be over kill ratings wise for an output impedance switch ?
https://surplustronics.co.nz/products/6 ... SVR4TXp3Xx


The other local option :

https://oamarucomputers.co.nz/product/s ... le-switch/


Or are the 250v 2A mini toggles from Jay car ok ?

It will work provided amp rating is sufficient and you only need to switch between two options. Also, it can get knocked out of position...

A better choice is this:

https://www.amplifiedparts.com/products ... position-0

I use these too - but the cost + freight cost makes it very expensive unless you are buying other parts at the same time.

[MikeC]

How much current is flowing?

Is this correct:
15w OT -> V = √PR
For an 8 ohm speaker V =√15x8 = 11v Current would be -> I=V/R = 11/8 = 1.4. for a 4ohm speaker 2.75 for a 16ohm speaker 0.7A

I was going to do 8/16 impedence switching
So the mini toggle should be ok?

For DC the formulea are correct. It will work for your scenario.

So, the speaker current is AC, not DC. But you can get an idea of the current & voltage handling required (the DC formula you've used gets you in the ballpark) then choose a switch with "better" (say double) ratings for current & voltage. Also consider the mechanical rigidity of the switch because it WILL get knocked! If it was a 100W amp I'd do the AC calcs or choose a switch/impedance selector that someone like Amplified parts sell.

[StrummersOfThunder]

How much current is flowing?

Is this correct:
15w OT -> V = √PR
For an 8 ohm speaker V =√15x8 = 11v Current would be -> I=V/R = 11/8 = 1.4. for a 4ohm speaker 2.75 for a 16ohm speaker 0.7A

I was going to do 8/16 impedence switching
So the mini toggle should be ok?

For DC the formulea are correct. It will work for your scenario.

How would the formulae look for AC?

[MikeC]

Is this correct:
15w OT -> V = √PR
For an 8 ohm speaker V =√15x8 = 11v Current would be -> I=V/R = 11/8 = 1.4. for a 4ohm speaker 2.75 for a 16ohm speaker 0.7A

I was going to do 8/16 impedence switching
So the mini toggle should be ok?

For DC the formulea are correct. It will work for your scenario.

How would the formulae look for AC?

Complicated!

[StrummersOfThunder]

For DC the formulea are correct. It will work for your scenario.

How would the formulae look for AC?

Complicated!

Yes... I just glanced at it. Wow. Back to school!

[StrummersOfThunder]

Populating the main board.

Still waiting on filter caps

[StrummersOfThunder]

Under board wiring done and board installed.
Starting the off board wiring

[jeremyb]

Jah bless!

[Jay]

I see you caps are roasted by my local cafe

https://sozocoffee.co.nz/

[StrummersOfThunder]

I see you caps are roasted by my local cafe

https://sozocoffee.co.nz/

Hopefully it doesnt smell the same when I fire it up !

Did you make yourself a current limiter or use a Variac ?

[Jay]

I see you caps are roasted by my local cafe

https://sozocoffee.co.nz/

Hopefully it doesnt smell the same when I fire it up !

Did you make yourself a current limiter or use a Variac ?

I use a poor man's 240VAC lightbulb

[StrummersOfThunder]

I see you caps are roasted by my local cafe

https://sozocoffee.co.nz/

Hopefully it doesnt smell the same when I fire it up !

Did you make yourself a current limiter or use a Variac ?

I use a poor man's 240VAC lightbulb

Care to post a diagram of it ?

[Jay]

It's just a bayonet fitting in series with the PT primary causing a voltage drop and a visual way of seeing what is going on. Too bright under no load and without valves is no good

[StrummersOfThunder]

Bit more progress last night.

All thats left now is to install the filter caps ( when they arrive) , heater filaments and OT.

[StrummersOfThunder]