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The DRD is on the breadboard [message #31196]

Mon, 27 June 2005 20:01

Forty2wo
Messages: 163
Registered: May 2009

Master

Working on the 45 version now. the plan is to be able to switch between 45 2a3 & 300b in the same amp.
working out some resistor values now.
If I can get my camera to talk to my computer again I will post a pic(I "upgraded" Windows)...John

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Re: The DRD is on the breadboard [message #31197 is a reply to message #31196]

Tue, 28 June 2005 17:01

colinhester
Messages: 1349
Registered: May 2009
Location: NE Arkansas

Illuminati (3rd Degree)

Get the camera fixed. Also, can you recommend a HV (1000VDC) hook-up for my 811 project?.......Colin

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Re: The DRD is on the breadboard [message #31198 is a reply to message #31197]

Tue, 28 June 2005 21:34

Forty2wo
Messages: 163
Registered: May 2009

Master

Hi Colin, I need more info. is the 1000v to come from the trans you got from me?
How much current?
tube or SS rectifier?
A look at the circuit would help.
damn camera still will not work I reloaded the software but it still will not transfer...John

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Re: The DRD is on the breadboard [message #31199 is a reply to message #31198]

Tue, 28 June 2005 22:13

colinhester
Messages: 1349
Registered: May 2009
Location: NE Arkansas

Illuminati (3rd Degree)

Here's the schematic (see link)

1) Yes, the 1000V (approx.) will come from the transformer I got from you.
2) Current I am assuming around 200mA
3) Tube rectified

Any suggestions you can offer a really, really appreciated.....Colin

http://www.audioroundtable.com/GroupBuild/Projects/SV811_10.gif

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Re: The DRD is on the breadboard [message #31203 is a reply to message #31199]

Wed, 29 June 2005 19:00

Forty2wo
Messages: 163
Registered: May 2009

Master

Hi Colin, By the looks of that schematic the B+ is 500v ~430v after the second choke. as shown it should work fine with the transformers I sent you.

I would remove the fuse after the rectifier, add a bleeder resistor say 100k 5w across the first cap and maybe increse the second cap a bit...John

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Re: The DRD is on the breadboard [message #31205 is a reply to message #31203]

Wed, 29 June 2005 20:28

colinhester
Messages: 1349
Registered: May 2009
Location: NE Arkansas

Illuminati (3rd Degree)

Just a little paranoid about the voltage coming off the rectifier. This is much greater than what I'm used to. Someone mentioned I need to be careful about arcing and that got me a little jumpy. I'm just trying to be safe and learn what needs to be done.

Some dumb questions, if you don't mind:

Why would you remove the second fuse?

Shouldn't I add bleeder resistors across all the PS caps, or will one suffice?

Why would you increase the second cap?

Thanks a million.......Colin

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Re: Power supply [message #31208 is a reply to message #31205]

Thu, 30 June 2005 19:54

Forty2wo
Messages: 163
Registered: May 2009

Master

Hi Colin,
I posted to this and I look it’s not there…I hate it when that happens.

Anyway.

Fuses can be iffy at high voltage, most are rated at 250V. An ac line fuses should be enough.

One bleeder is enough, just don’t count on it for safety. Check before you touch.

Why a bigger cap; because you can! Before we glommed on to motor runs 10u was big, and expensive, and probably filled with PCB’s I increased the output tube cap on my WE91’s from 50u to 100u , Much better bass and dynamics…John

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