Search found 20147 matches

by Mike H
Sat Mar 16, 2024 10:08 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 135
Views: 23767

Re: OK…so I’m on wi’ summat

Absolutely fab. :thumbright:
by Mike H
Sat Mar 16, 2024 10:04 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

With improved output transistor biasing - originally thermistors were added for safety, they basically went across the transformer secondaries, because the DC resistances of same formed part of the resistor divider that biases each o/p transistor, as per the Burns-Orbit. The original thermistors are...
by Mike H
Sat Mar 16, 2024 8:06 pm
Forum: Assorted Stuff
Topic: Owston 2024?
Replies: 1
Views: 156

Re: Owston 2024?

I am also interested. Almost guaranteed MCRU would be as well. :D
by Mike H
Sat Mar 16, 2024 8:04 pm
Forum: Assorted Stuff
Topic: General health matters.
Replies: 784
Views: 183449

Re: General health matters.

Ah the pressure tester thing! It is impossible not to blink.
:D
by Mike H
Sat Mar 16, 2024 3:36 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

First 30 seconds of a WAV file - Life Is A Long Song by Jethro Tull..... :D - Germanium amp 2024-C4-wav.png - I had the EP of this when it first came out, so 1971-ish, ad often used it as a 'test signal' for whatever I was building at the time. Not an ideal choice to be honest, and caused a bit of h...
by Mike H
Sat Mar 16, 2024 3:29 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

Frequency sweep, checks out OK...
-
Germanium amp 2024-C4-noise.png
Germanium amp 2024-C4-noise.png (9.99 KiB) Viewed 183 times
-

Noise plot, it is what it is...
-
Germanium amp 2024-C4 f-sweep.png
Germanium amp 2024-C4 f-sweep.png (9.09 KiB) Viewed 183 times
-

Clipping with 2V peak input. No unexpected behaviour...
-
Germanium amp 2024-C4-clip 2V.png
Germanium amp 2024-C4-clip 2V.png (12.23 KiB) Viewed 183 times
-
by Mike H
Sat Mar 16, 2024 3:25 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

Alright, so then I found this fabulous thing - it's another one from the school exercise book... this is Fig 10.38 from the original library book... - Fig1028.jpg - They are taking the NFB back to the driver stage emitter, so I tried that... first I did what you suggested, take it back to base, that...
by Mike H
Sat Mar 16, 2024 3:13 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

Definitely got that going on hasn't it? This is a bit too new, let's go with what we know ... :lol:
by Mike H
Sat Mar 16, 2024 10:19 am
Forum: Jokes
Topic: A little light humour
Replies: 2698
Views: 1135023

Re: A little light humour

:D




-
In case of fire air horn.jpg
In case of fire air horn.jpg (62.39 KiB) Viewed 508 times
by Mike H
Sat Mar 16, 2024 10:12 am
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

But I wonder if its worth trying a NPN for Q1 and taking the feedback back to Q1's base. Oh wait, sorry I misunderstood - forgot where 'Q1' was - I know what you mean now - I shall have a ponder..... back shortly ... "I have a cunning plan my lord" http://livinginthepast-audioweb.co.uk/im...
by Mike H
Fri Mar 15, 2024 8:44 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

Ah found a picture ...
-
cv7084_box.jpg
cv7084_box.jpg (47.95 KiB) Viewed 257 times
by Mike H
Fri Mar 15, 2024 8:36 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

This is cobblers and do this better is my kind of self-encouragement! :lol: I was part-paid (aka "take them please before I dump them on eBay") for a repair job a while back in a few OC35s! Matched pairs apparently back in the 60s or 70s and stored in these polystyrene boxes. Shiny shiny!...
by Mike H
Fri Mar 15, 2024 8:30 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

Ray P wrote: Mon Mar 11, 2024 7:32 pm Warmer weather is on the way Mike, soon be working on your geranium amplifier...
As usual, the last few days I've been down a different rabbit hole...
by Mike H
Fri Mar 15, 2024 8:29 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

Just a couple of thought, you are never going to be able to use much in the way of negative feedback in that amp (at least by comparison with a modern direct coupled circuit. That interstage is going to add so much group delay and general phase shifting nastyness that the most you can manage is PP ...
by Mike H
Fri Mar 15, 2024 8:19 pm
Forum: Solid State
Topic: Germanium Amplifier
Replies: 162
Views: 79753

Re: Germanium Amplifier

andrew Ivimey wrote: Sat Mar 09, 2024 7:32 am PNP oc35s ( never heard of them) I always thought oc28s were the swanky ones!

I'd like to hear them.
And these are ex-RAF military ones, so even swankier. :D