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Old 20th August 2012, 11:41 PM   #1261
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Tube Rectifier - that would be the Jessica Amp.

Here is the Power Supply I used for Jessica's BH.

Cheers,
Ian
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Old 20th August 2012, 11:53 PM   #1262
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The rest of the Jessica Amp for info

Note this was a 6V6 + 6SL7 version.

Cheers,
Ian
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Old 21st August 2012, 12:01 AM   #1263
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For a simple but effective solid state high voltage (series not shunt) regulator see the pdf attached to dupyv (the other Yves) post #369

Cheers,
Ian
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Old 21st August 2012, 09:26 AM   #1264
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Quote:
Originally Posted by gingertube View Post
Tube Rectifier - that would be the Jessica Amp.

Here is the Power Supply I used for Jessica's BH.

Cheers,
Ian
That's interesting, I've been meaning to build a Baby Huey with tube rectification.

The obvious choice would be an EZ81 rectifier, however I will be using all-Russian (6P14P and 6N2P) tubes for my BH so ideally I want to use a Russian rectifier too. The Russians never seemed to have made a noval rectifier however, so I'm pretty much "stuck" with using a 5C4S, which is supposedly a 5Z4GT. I also have some nice 100uf film caps I want to use as a power supply reservoir cap.

Do you think I can run 4 EL84's and 2 6N2P's on one 5C4S? What would the total current draw be?

I'm using a 300-0-300 trans, 250mA
4,7uF behind the rectifier (this is a downside, because the ez81 can handle 50uF), a 10H choke with 100uF cap, then the EL84's.

I simulated this with PSUD (using 5Y3-GT as rectifier).
This gives me a B+ of about 285 volts. Is this sufficient? I think so?

Any other configuration that works better? Should I just ditch the valve rectification idea? (My trans does not have a 5v winding so I'll need a separate one anyway.)
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Old 21st August 2012, 10:53 PM   #1265
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Default Baby Huey Power.

Quote:
Originally Posted by gingertube View Post
For a simple but effective solid state high voltage (series not shunt) regulator see the pdf attached to dupyv (the other Yves) post #369

Cheers,
Ian
Hi Ian,

I have successfully built a phono stage and preamp from drawings but never a power amp. My tech knowledge is minimal. But with all the info here I am pretty sure I can do the Baby Huey.
I think, as I am a complete newbie, I will stick to your original schematic, keep it as simple as possible and use solid state in the PS. I can always have a go dupyv's regulated PS later.

Please can you tell me what voltage center tapped transformer is used in your original schematic? I can get a 240-0-240 @ 200mA transformer with 5V@2A and 6.3V@5A windings. I think this should give about 325v DC before smoothing. Is this correct?

Thanks.

Ian M.

Last edited by sharkey22; 21st August 2012 at 11:23 PM.
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Old 21st August 2012, 11:28 PM   #1266
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Sharkey22 (Ian M.),
Wioth 350-0-350 and Solid State Rectifier you will get a lot more than 315V DC (unless using a choke input power suppy).
For the original BH (schematic back on page 1) with a solid State Rectifier you want 240-0-240 typical, up to 285-0-285 would do but give you a higher B+ voltage.
I've also used a non centre tapped 240V AC secondary with a bridge rectifier successfully.
PSUD2 is your friend,
PSUD2 can be downloaded from here:
Duncan's Amp Pages
Cheers,
Ian (thats Ian M. as well).
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Old 22nd August 2012, 12:44 AM   #1267
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Hi Ian, looks likeyou read my post before I edited it. If you look back you will see that I had sort of corrected my own error regarding voltages.

Just got PSUII and modelled a few variations. My original and way too high estimate was based on the Hammond rectification guide that suggests that DC output from HWCT Solid state is 0.45 x secondary AC output. (am I missing something here? think i was looking at choke input figures) Whereas in reality it is about 1.4 x secondary. I had tried using PSU11 a few times but have literally only just got the hang of it. Is there a dummies guide to psu11 anywhere?

I have already ordered a transformer with 280-240-0-240-280 @ 220mA. with 6.3 and 5 volt windings (future proof!)this should do for solid state or valve rectifier as I please with loads of current to play with. Custom built for about 60 UK. Bargain.

thanks for your help. Ian.
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Old 22nd August 2012, 12:54 AM   #1268
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I also have a choke out of an old push pull el34 amp. Sure i can utilise this in some way but as yet i dont know its value. Should handle the current though. Is there a simple way of measuring the inductance without a LCR meter?

If i use a bridge rectifier i could use one of these? Dont know if i am allowed to post links but here goes.

http://www.ebay.co.uk/itm/BLOCK-UNIV...item2a1af7e6fe

Last edited by sharkey22; 22nd August 2012 at 12:58 AM. Reason: Adding text.
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Old 22nd August 2012, 12:59 AM   #1269
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All the texts will tell you that an LCR meter will give you a wrong reading of the inductance due to lack of DC in the choke while measuring (LCR meters use AC excitation only).

BUT
All the chokes I have measured with my LCR meter have given readings about 20% low. That is probably within the meter accuracy, choke tolerance etc., so use your LCR meter with a reasonable confidence of getting about the right value.

Cheers,
Ian
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Old 22nd August 2012, 09:02 PM   #1270
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OK, so I have not got an exact value for the choke yet but I have had a bit of a read and experimented with PSUD2. Not sure that it is perfect but I think I have what looks like a fairly smooth arrangement for my power supply.

Is it OK to add resistors before the diodes in order to tweak the final B+?
Also I only know the resistance of the choke without load, I presume this will rise under load.

Can you have a glance at the design and confirm that it is OK.

Cheers Ian.
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