#1
Hi guys,

As previously mentioned in another post, I am designing a high voltage valve preamplifier. High voltage, so I am going to want a mains transformer... Anyone know of a good place to buy a transformer with following specs?

Primary Voltage - 230v RMS (UK Mains)
Secondary Voltage #1 - 230v RMS
Secondary Voltage #2 - 6.3v RMS
Pref. Toroidal

I'll only be running one double triode and maybe a MOSFET cathode follower or something so power rating shouldn't be too big a worry.

So where do I order in the UK when time is a consideration (i.e. no custom orders)?
Guitars & Gear:
Parker Nitefly M
Sumer Metal Driver
Ibanez RGD2120Z
AMT SS-11B
Two Notes Torpedo CAB
#2
this may be a good option:

http://pr.mouser.com/ProductDetail/Hammond-Manufacturing/229B230/?qs=sGAEpiMZZMvwUzoUXIIvyQPvPmwnNFGy8Wa27RMJLfk%3d

or this if your not doing pcb:
http://pr.mouser.com/ProductDetail/Hammond-Manufacturing/185C230/?qs=sGAEpiMZZMvwUzoUXIIvyQPvPmwnNFGyoltxcoCVeAI%3d

and this for filaments:
http://pr.mouser.com/ProductDetail/Hammond-Manufacturing/266GB6/?qs=sGAEpiMZZMvwUzoUXIIvyW8HfC4QLhUepn%252bAYAdoglo%3d

didnt find any hammond transformers with all your specs, but this should work just fine and be cost effective. if its just 1 tube and a mosfet, you dont really need high spec parts.
Marty Friedman is GOD!

curently in a SEX MACHINEGUNS and X JAPAN phase AND Galneryus AND Anthem phase

damn J-Metal, why you so awesome

My Gear:

Schecter Hellraiser V-1 fr
Ibanez RG321mh
Fender GDC-200sce
Peavey Vypyr 30 w/ sanpera 1
Last edited by bustapr at Oct 14, 2013,
#4
According to my big book of knowledge by Merlin the Valve Wizard, toroidals have better saturation characteristics and are often smaller. Obviously, this is the least important spec.
Guitars & Gear:
Parker Nitefly M
Sumer Metal Driver
Ibanez RGD2120Z
AMT SS-11B
Two Notes Torpedo CAB
Last edited by Emperor's Child at Oct 14, 2013,
#5
As I'm a bit new to the practical use of transformers, I've got more questions:

1) Is the fact that the above transformers are listed as dual primary and dual secondary irrelevant since I only need one 230v secondary and one 6.3v secondary?

2) Am I right in thinking that, if I want to connect these transformers to the mains I need to link the connections of one primary to the connections on the primary of the other transformer (as if run in parallel...sort of).

3) Am I also right in thinking that power ratings aren't going to be much of a concern when I'm only doing a preamp (no power section)?

4) Can someone remind me what the purpose of a 230v-230v transformer is?
Guitars & Gear:
Parker Nitefly M
Sumer Metal Driver
Ibanez RGD2120Z
AMT SS-11B
Two Notes Torpedo CAB
Last edited by Emperor's Child at Oct 14, 2013,
#6
1) dual-primary usually means that both are rated for a specific voltage--in this case 120v--so you'd wire them in parallel for a 120v line and series for a 240v line.

2) yes, no matter how many PT's you are using, their primaries will be wired across the mains.

3) You should always be concerned about the current and power ratings of transformers. Just be sure they can handle the application.

4) it is an isolation transformer. Put an AC votage on the primary, you'll get (about) the same voltage on the secondary. some stuff (computers, TVs, certain cheap old tube gear, etc) are connected directly to the line so there is no isolation between you and the hot wire. If you touch the hot wire, you get shocked but if you touch the neutral wire you won't. This makes servicing electrical stuff dangerous. with an isolation transformer, the only way you can get shocked is if you grab both wires at the same time. touching either wire alone won't hurt you.

these things can also be used as power transformers for tube circuits, as even our 120v mains is good enough for a small low-power amps. your 240v mains is even better because the voltage is higher.
#9
Quote by Invader Jim
Now you're getting into the audiophool stuff...


Is that because it's toroidal? ...because I might be trying to fit all the circuitry in a slimline rack unit or pedal enclosure, which would make the toroidal more ideal right?

After a bit of research I do see that toroidal isn't necessarily 'better' though.
Guitars & Gear:
Parker Nitefly M
Sumer Metal Driver
Ibanez RGD2120Z
AMT SS-11B
Two Notes Torpedo CAB
#10
I'm just saying that's what an audiophile/tonechaser would use I'm not a fan of those kinds of people. Imho if it sounds good it is good.

But if it suits the application then by all means use it. Don't let a jerk like me stop you