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Old 13th October 2011, 09:20 PM   #201
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Yup--Sounds like yours nearly ready to run....

There was a little confusion fairly early on in the thread regarding the SL/SN tube issue, as this thing has gone through more versions than a Ford Transit...

Fairly settled now on the above scheme though!

Ive done some experimenting with cathode-follower drive to the 6C33 but no real benefit for 'normal' listening, just makes the O/P slightly higher before obvious clipping,--Not really worth the effort, and adding another valve per channel.

--Still to try driving the 6C33 with MOSFET followers for a larf, --just to see what difference there is...
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Old 13th October 2011, 09:24 PM   #202
M Gregg is offline M Gregg  United Kingdom
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6c33c's

have been run for 12hrs heaters on so I hope they will be OK.

I want to look at switching the B+ for a standby function.

The input selector works OK.

I notice a few sites driving the 211/845 with SS.

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M. Gregg
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Old 13th October 2011, 09:31 PM   #203
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Guess for +B switching, you could just have a switch that cuts the power to the large toroid that only supplies the 6C33 +/-B rails....

The pre-amp sections are not so important with regards that so can be left as normal.

I dont have a 'Standby' function--Never have, Its full +/-B from stone-cold!
--65 million TV sets can't be wrong!
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Old 13th October 2011, 09:35 PM   #204
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Alastair E View Post
Guess for +B switching, you could just have a switch that cuts the power to the large toroid that only supplies the 6C33 +/-B rails....

The pre-amp sections are not so important with regards that so can be left as normal.

I dont have a 'Standby' function--Never have, Its full +/-B from stone-cold!
--65 million TV sets can't be wrong!
The thought was to burn in new tubes with no HT on.
No thought to delay B+ at the start.
Maybe relay switch B+ from the selector switch.
One position would be B+ off

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M. Gregg
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Old 13th October 2011, 09:39 PM   #205
M Gregg is offline M Gregg  United Kingdom
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LOL,

look at the names in the forum...LOL

One can't forget 6SN7...lol

Anyway catch you laters....Thank's again!
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Old 15th October 2011, 05:13 PM   #206
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No IRF710 in stock at my supplier

Have to check my leftovers for some substitute.
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Old 15th October 2011, 05:44 PM   #207
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IRF 820 isnt a bad alternative, reasonably low capacitance 350 odd pF as I recall, and 2.5A and 500V, 50W p diss....

IRF 830 Ive used in the past but the gate-capacitance is higher at 600 odd pF, --Works OK though....

Basically any 'N' channel MOSFET with a high enough voltage-rating for the circuit, (So above 350V) and a low gate-capacitance will be fine...
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Old 15th October 2011, 06:55 PM   #208
M Gregg is offline M Gregg  United Kingdom
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B+ relay fitted.
Switched from selector switch.

Just for interest I didn't want to use a neon for the supply indication: 240v AC. I remembered a circuit using a capacitor to replace the resistor for an LED. This is close I think, I haven't had chance to test and check it yet . Looks close though! Cap might be .22uF for 240V....Toroid has no low voltage out..

Link:
http://www.turbokeu.com/myprojects/acled.htm

Should also work with opto-isolaters.

I got my IRF710's from Farnell.

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M. Gregg
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Old 15th October 2011, 08:50 PM   #209
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Nothing even close to a good substitute for IRF710.

Closest i found was a IRF740 and specs wasn´t very good.

Has to order some IRF710 on monday.

M Gregg you´re running and i feel like crawling uphill
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Old 16th October 2011, 10:14 PM   #210
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by flatheadmurre View Post
Nothing even close to a good substitute for IRF710.

Closest i found was a IRF740 and specs wasn´t very good.

Has to order some IRF710 on monday.

M Gregg you´re running and i feel like crawling uphill
Your doing fine!

Looking forward to your progress.

Regards
M. Gregg
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