Germanium Amplifier
- Mike H
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#46
I am beginning to understand why it used to take me so long working out actual usable transistor circuits that will remain stable and work reliably, compared to this valves are a doddle
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- pre65
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#47
So Mike, after all this thinking, calculating and "wallowing" in nostalgia about Germanium transistors ( ) do you think the final results will be worthwhile ?
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
- Mike H
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#48
Haven't the faintest idea, but there's all this ranting going on on the web about how germaniums sound good.
Even to the extent of converting to germanium outputs on anything modern. How about that.
Mainly though it's the challenge
But is becoming a bit of a marathon must be said. Wasn't supposed to be this difficult or involved originally
Even to the extent of converting to germanium outputs on anything modern. How about that.
Mainly though it's the challenge
But is becoming a bit of a marathon must be said. Wasn't supposed to be this difficult or involved originally
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- pre65
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#49
So has anything in the way of germanium transistors been produced in recent times ?
Or is it just old stock being used up.
Or is it just old stock being used up.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
- Mike H
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#50
Good question ~ prices may indicate NOS, RS have got a few (and they are few) so could be surviving old stock
http://uk.rs-online.com/web/search/sear ... &x=29&y=12
Cricklewood seem to have lots, but only if it's actually got a 'buy now'
http://www.cricklewoodelectronics.com/C ... rch&page=1
See them weird brass coloured 2N174 types? Tried some of those once. And blew them up Didn't cost £40 each though, more like 2 quid IIRC
Only thing is with these survivng old stock can't get exactly what you want, I expect the most popular ones have all been used up so you're kind of left with "the dregs"
http://uk.rs-online.com/web/search/sear ... &x=29&y=12
Cricklewood seem to have lots, but only if it's actually got a 'buy now'
http://www.cricklewoodelectronics.com/C ... rch&page=1
See them weird brass coloured 2N174 types? Tried some of those once. And blew them up Didn't cost £40 each though, more like 2 quid IIRC
Only thing is with these survivng old stock can't get exactly what you want, I expect the most popular ones have all been used up so you're kind of left with "the dregs"
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- pre65
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#51
I'll make some if you like.
Monday I have to build a Nuclear power station,
Tuesday I have to negotiate with the Taliban,
Wednesday is lunchtime concert,
Thursday is free.
Monday I have to build a Nuclear power station,
Tuesday I have to negotiate with the Taliban,
Wednesday is lunchtime concert,
Thursday is free.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
- Mike H
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#55
Found some CV7084 (military version OC35 power tranny) on eBay [Langrex shop], cheaper'n Cricklewoods so might have a go at making the output as germanium p-p. Have to be contrived as Darlingtons though as the transformer is very small (read as, base current can't exceed 1mA)
They also got CV8314 (OC76) only £2 each which will do for the pre-amps so will have some of them as well.
They also got CV8314 (OC76) only £2 each which will do for the pre-amps so will have some of them as well.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#57
So looks like will have two AC128 left over, so last night I quickly scribbled this sketch for a high impedance input buffer. (Well reasonably high impedance input.)
Remember the low impedance input problem with the tone control network, 'speshly as regards the HF end, 'cause of the capacitors in it? Would help greatly if could be driven from a low impedance source.
And voila....
Remember the low impedance input problem with the tone control network, 'speshly as regards the HF end, 'cause of the capacitors in it? Would help greatly if could be driven from a low impedance source.
And voila....
- Attachments
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- AC128 buffer1.gif (6.89 KiB) Viewed 3709 times
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#58
Interestingly there's no signal loss here, not like wot you get with a FET or a cathode follower! (I was thinking of using a FET buffer earlier on)
Put 1 Volt in, you get 1 Volt out. No less.
Input impedance is 300 kilohms, not at all shabby so means I can use a 100k log pot for volume (found I've got two stereo gangs going spare doing nothing)
Put 1 Volt in, you get 1 Volt out. No less.
Input impedance is 300 kilohms, not at all shabby so means I can use a 100k log pot for volume (found I've got two stereo gangs going spare doing nothing)
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#60
And the output be remains flat when vol pot not at maximum (and tone controls in the middle):
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- Transistronics-Tone Control-graph.gif (7.75 KiB) Viewed 3702 times
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."