Power op amp driving valve in A2

If they glow, this is the place to be
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#46

Post by Mike H »

Sorry datasheet sez 32W r.m.s. into 8R, supply +/- 22V! Image

Nuffink to do wiv me guv

Nope, don't compute do it? :lol:

Maybe if supply +/- 25V, which it can accept
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#47

Post by pre65 »

In reality it might have to be an 18-0-18 transformer. :(
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#48

Post by Mike H »

Well that's alright that gives you +/- 25V DC, you can't put more than that across the chip, it's the maximum.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Nick
Site Admin
Posts: 15704
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#49

Post by Nick »

Mike H wrote:Sorry datasheet sez 32W r.m.s. into 8R, supply +/- 22V! Image

Nuffink to do wiv me guv

Nope, don't compute do it? :lol:

Maybe if supply +/- 25V, which it can accept
Yep, but 10% distortion can give you some scope for clipping of peaks.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#50

Post by pre65 »

I tried re-sending my e-mail to P Millett tonight and he has just replied.

So, might put this back on the to-do list. :)
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#51

Post by Mike H »

More details? :?:
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#52

Post by pre65 »

Not much really. He used a 100R resistor between op amp and 1626 grid to stop shorts.

There were two capacitors in the picture, one was the 1626 cathode bypass cap the other was a mystery.

DTB reckoned it was a PSU cap and guess what, he was right.

So, just need to get myself a couple of driving modules now, will probably come from HK but I'm in no hurry.
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#53

Post by pre65 »

The TDA2050 modules (2) have finally been dispatched after a long delay due to some Chinese holiday (?).

Perhaps by the time they get here my enthusiasm will have returned. :wink:
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12273
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#54

Post by Dave the bass »

It was Chinese new year ya wally! :lol: Its year of the Muvver-in-Law...ooops sorry... I meant year of the Dragon.

DTB
"The fat bourgeois and his doppelganger"
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#55

Post by Mike H »

:lol:
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#56

Post by pre65 »

Well, after the delay in despatch (cos of DTB mother in law :wink:) they actually arrived on Friday.

This morning I patiently soldered (welded ?) all the bits to the two PCB's, so now the project is back on track.

Just need to find my notes so I can see what the plan is. :?
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#57

Post by pre65 »

I'm screwing all the bits onto an old bit of kitchen worktop.

HT PSU is fixed down now, next up is the two driver modules and the octal bases. One dual sec (0-18 + 0-18) toroid paralleled is powering the modules with a 62mh choke and a couple of caps.

1626 heaters are AC with two small 0-6 + 0-6 transformers in series, one for each valve.

I think I've got it all worked out now so just need a bout of sustained enthusiasm. :wink:

Technical question.

On the 0-6v + 0-6v transformers (in series to give 12v) can I use them as centre tap to ground ?
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#58

Post by Mike H »

It appears to be indirectly heated, so looks like you could yes.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#59

Post by pre65 »

I had a bit of trouble getting near enough to 12.6v with the transformers I was using, so have gone back to plan A and use the 12v bench PSU, that will give me 12.4v DC which will do for the first iteration.

I had a burst of enthusiasm at 10.00 tonight and not much more to do now.

Here's a view of it as is.

Image
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#60

Post by pre65 »

IT WORKS ! :D

Now to have a listen with a few test discs. :wink:
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
Post Reply