DCAudioDIY.com

DC Area Audio DIYer's Community
It is currently November 15th, 2018, 12:27 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 7 posts ] 
Author Message
 Post subject: OA2 shunt csp
PostPosted: August 27th, 2018, 2:47 pm 
Offline
User avatar

Joined: December 14th, 2013, 2:19 pm
Posts: 589
I know that an 0A2 wil oscillate if too much capacitance is used shunting it. I use 0.01uF typically. What about an RC network after it. To provide a bit of filtering after the regulator, and to isolate channels, I'm thinking of using a 2.2k resistor and 22.5kuF cap for each of two channels connected to the CCS/SR consisting of two stacked 0A2 and a 10M45S. Each RC will see about 2.5mA. Will this cause instability?


Top
 Profile  
 
 Post subject: Re: OA2 shunt csp
PostPosted: August 27th, 2018, 4:02 pm 
Offline
User avatar

Joined: July 24th, 2015, 4:17 pm
Posts: 736
Location: Parkville, Maryland
Stuart Polansky wrote:
I know that an 0A2 wil oscillate if too much capacitance is used shunting it. I use 0.01uF typically. What about an RC network after it. To provide a bit of filtering after the regulator, and to isolate channels, I'm thinking of using a 2.2k resistor and 22.5kuF cap for each of two channels connected to the CCS/SR consisting of two stacked 0A2 and a 10M45S. Each RC will see about 2.5mA. Will this cause instability?



Now you're getting fancy. I haven't seen anyone mention OA2s since I read a vintage article decades ago on regulated power supplies.

_________________
Walt


Top
 Profile  
 
 Post subject: Re: OA2 shunt csp
PostPosted: August 27th, 2018, 5:31 pm 
Offline
User avatar

Joined: December 14th, 2013, 2:19 pm
Posts: 589
It seems that it's true that 0A2s are quiet IF fed by a CCS.
Since the circuit needs 300-310 volts.........bingo. Way simpler than a Camille circuit, and should be perfectly adequate.
But RC filtering afterwards helps with SS regulators, seems like it should also help with a hybrid circuit. As long as the 0A2 doesn't go crazy.


Top
 Profile  
 
 Post subject: Re: OA2 shunt csp
PostPosted: August 27th, 2018, 6:54 pm 
Offline
User avatar

Joined: July 24th, 2015, 4:17 pm
Posts: 736
Location: Parkville, Maryland
Stuart Polansky wrote:
It seems that it's true that 0A2s are quiet IF fed by a CCS.
Since the circuit needs 300-310 volts.........bingo. Way simpler than a Camille circuit, and should be perfectly adequate.
But RC filtering afterwards helps with SS regulators, seems like it should also help with a hybrid circuit. As long as the 0A2 doesn't go crazy.


Plus you get a cool glow from the tube.

_________________
Walt


Top
 Profile  
 
 Post subject: Re: OA2 shunt csp
PostPosted: August 27th, 2018, 7:23 pm 
Offline

Joined: February 28th, 2013, 1:19 pm
Posts: 220
Stuart,

Just a small amount of resistance is all you need, what you are proposing is overkill, and will greatly impact the regulation. Besides, you might run into light-of problems with the current being pulled by the charging capacitor. If I read this right, you are using it as a pre-regulator followed by another 0A2 shunt?

You might also want to try the Statistical Regulator of Martin Jones. A string of 5.8V or 6.2V zeners (alot of zeners). Fed with a current source he claims amazingly low noise.

David


Top
 Profile  
 
 Post subject: Re: OA2 shunt csp
PostPosted: August 27th, 2018, 11:48 pm 
Offline
User avatar

Joined: December 14th, 2013, 2:19 pm
Posts: 589
David,

I'm doing a crappy job of communicating. Please see attached scribbling to understand what I'm doing.

I'll certainly make the 2.2k smaller,if it will not oscillate. Since this is a simple class A gain stage, I'm not too worried about B+ fluctuations because of high DCR. Still, if 100R or even less will keep the tube stable, I'll do it.

Thanks,

Stuart


Attachments:
PS.png
PS.png [ 1.08 MiB | Viewed 891 times ]
Top
 Profile  
 
 Post subject: Re: OA2 shunt csp
PostPosted: August 28th, 2018, 1:14 pm 
Offline

Joined: February 28th, 2013, 1:19 pm
Posts: 220
Stuart,

Only need about 100 to 200 ohms. If you want/need to have separate supplies as you show, it is better to have two regulators rather than do what you are doing, which defeats the effectiveness of the shunt regulator (increasing regulator impedance).

David


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 11 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group