Search found 1456 matches
- Tue Feb 27, 2024 10:33 pm
- Forum: Everyones Projects
- Topic: 6550 SE Amplifier
- Replies: 110
- Views: 11193
Re: 6550 SE Amplifier
Brilliant news Paul, well done!
- Sat Feb 24, 2024 4:37 pm
- Forum: Assorted Stuff
- Topic: what are you doing ?
- Replies: 1308
- Views: 473583
Re: what are you doing ?
Hercules cluster, single 30s exposure - bit out of focus, sorry.
- Mon Feb 19, 2024 10:30 pm
- Forum: Everyones Projects
- Topic: On My Bench.
- Replies: 93
- Views: 31496
Re: On My Bench.
Narco Avionics - sounds like a Colombian import-export company…
- Fri Jan 12, 2024 10:14 pm
- Forum: Assorted Stuff
- Topic: what are you doing ?
- Replies: 1308
- Views: 473583
- Fri Jan 12, 2024 7:17 pm
- Forum: Assorted Stuff
- Topic: what are you doing ?
- Replies: 1308
- Views: 473583
Re: what are you doing ?
Been having a tidy up on the computer and came across this photo. In 2016 we visited a part of France with pretty dark skies (Astrofarm in Confolens). This was a single 30 second shot of the Milky Way, ISO 3200, can't remember what lens but possibly a Rokinon 135mm. I've just given it a bit of a twe...
- Thu Jan 11, 2024 6:07 pm
- Forum: Assorted Stuff
- Topic: Nothing In Particular
- Replies: 16489
- Views: 4845370
Re: Nothing In Particular
I use a pfSense based box both here and at work. Very flexible. The one at work sits behind a 10Gb line. If you have a old PC sitting about that can have two network interfaces it can be reused as a perfectly good firewall. The pfSense box here is on a tiny single board computer, and uses a TP Link...
- Thu Jan 11, 2024 12:25 pm
- Forum: Assorted Stuff
- Topic: Nothing In Particular
- Replies: 16489
- Views: 4845370
Re: Nothing In Particular
Thanks for that very comprehensive reply Nick
I just checked my ISP router settings and I'm not forwarding any ports so that's good!
I just checked my ISP router settings and I'm not forwarding any ports so that's good!
- Thu Jan 11, 2024 10:51 am
- Forum: Assorted Stuff
- Topic: Nothing In Particular
- Replies: 16489
- Views: 4845370
- Wed Dec 20, 2023 7:38 am
- Forum: Everyones Projects
- Topic: GM70 Amplifier
- Replies: 103
- Views: 91101
Re: GM70 Amplifier
Good point, I’d forgotten that, thanks Nick
- Tue Dec 19, 2023 11:36 pm
- Forum: Everyones Projects
- Topic: GM70 Amplifier
- Replies: 103
- Views: 91101
Re: GM70 Amplifier
One last thought - if we use a ccs load, and it’s a perfect ccs, does it matter anymore whether we bypass the cathode resistor? Because the voltage across the resistor won’t change.
- Tue Dec 19, 2023 11:33 pm
- Forum: Everyones Projects
- Topic: GM70 Amplifier
- Replies: 103
- Views: 91101
Re: GM70 Amplifier
Yes, 6J5 is the same as one half of a 6sn7 or 12sn7 or 7n7
- Tue Dec 19, 2023 11:27 pm
- Forum: Everyones Projects
- Topic: GM70 Amplifier
- Replies: 103
- Views: 91101
Re: GM70 Amplifier
Ive never forgotten what Morgan Jones said in Vry’s flat. “Why not use youre main b+ to load your voltage amplifier with High value resistance.” My 211 push-pull amp used that idea, I had around 750 volts after smoothing. The input/gain stage used 50K loads, and the phase-splitter used about 25K to...
- Tue Dec 19, 2023 8:00 pm
- Forum: Assorted Stuff
- Topic: what are you doing ?
- Replies: 1308
- Views: 473583
Re: what are you doing ?
Sounds like an interesting evening Nick.
One of my local societies is having a stargazing evening at Rutherford Appleton Lab soon. I think I’ll check it out.
One of my local societies is having a stargazing evening at Rutherford Appleton Lab soon. I think I’ll check it out.
- Sun Dec 17, 2023 8:42 am
- Forum: Everyones Projects
- Topic: GM70 Amplifier
- Replies: 103
- Views: 91101
Re: GM70 Amplifier
Another option might be 5687 (or whatever else you have that’s suitable) for first gain stage, and xn7 for second stage (you only need the big voltage swing for the second stage). Thinking about the cf stage, do you need the negative bias voltage to be there before the GM70 starts operating? Which m...
- Sat Dec 16, 2023 9:28 am
- Forum: Everyones Projects
- Topic: GM70 Amplifier
- Replies: 103
- Views: 91101
Re: GM70 Amplifier
Hi Paul Following this with interest, looks like a nice project :) I’m a bit confused by the gain calcs - I thought 6j5 would have higher gain than 5687? (Actually it’s irrelevant because I think I agree with your conclusion that either will work :)) I have some metal envelope 6j5s and should be abl...