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-   -   The Kuartlotron - keantoken's simple error-correction superbuffer (https://www.diyaudio.com/forums/analog-line-level/251413-kuartlotron-keantokens-simple-error-correction-superbuffer.html)

silasmellor 22nd September 2018 07:47 PM

Yeah I think it’s at min value, so essentially r9 is jumpered. Not sure what to make of it. On start up, tp slowly goes to 5v and offset to1-2mV.

silasmellor 22nd September 2018 07:48 PM

Quote:

Originally Posted by silasmellor (https://www.diyaudio.com/forums/analog-line-level/251413-kuartlotron-keantokens-simple-error-correction-superbuffer-post5553052.html#post5553052)
Ok, using the 1M trimmer without the series 1.8M also works, so I suspect I’m just at the end of the travel for the pot, probably at low R. Would it make sense to try something even higher, like 2.2M for the Series resistor to R9? Is Avery low resistance for R9 a problem?

Sorry, that post should have said “without the 1.8M series resistor...”

silasmellor 22nd September 2018 09:22 PM

Ok I think my benchtop psu might have been the issue. I switched over to the intended psu, 10v bipolar using Nisbeths standalone whammy psu boards. Added another 500k in series with the 1.8M one and offset is only a few mV without any trimming. I can play music through it so I guess it works, but I will try the fft to check distortion (though I doubt I can trim much as my interface won’t go below 0.006%.

Sorry for the confusion, not sure why the benchtop psu was giving odd results, it has +/- and gnd taps, but measuring gnd to either + or - showed 0V so something must have been off there...

Zoran 12th November 2018 08:59 PM

Hi Ken. Could You transcribe superbuffer to Germanium transistor version?
(I have one full Ge amp and it need buffer to drive input transformer...)
I know that old Ge-s are maybe inferior against contemporary Si BJTs but I just dont like idea to mix...
thanks

keantoken 6th December 2018 04:59 AM

Sorry, for some reason I tend to stop getting notifications from this thread.

I could take a stab at it, but I need to have datasheets for the parts you have available.

keantoken 6th December 2018 05:48 AM

I tried the Kuartlotron in the simulator with AC127/128 models, it does surprisingly well. Unfortunately not all Ge transistors are as useful as these.

The OC70 has a transition frequency of 15KHz. If I heard of a modern transistor with a Ft of 15KHz, I would assume it weighs about 100LB and is used only in special super high power applications.

Zoran 24th December 2018 04:42 PM

Quote:

Originally Posted by keantoken (https://www.diyaudio.com/forums/analog-line-level/251413-kuartlotron-keantokens-simple-error-correction-superbuffer-post5623708.html#post5623708)
I tried the Kuartlotron in the simulator with AC127/128 models, it does surprisingly well. Unfortunately not all Ge transistors are as useful as these.

The OC70 has a transition frequency of 15KHz. If I heard of a modern transistor with a Ft of 15KHz, I would assume it weighs about 100LB and is used only in special super high power applications.

Thanks for answering Ken :)
(I need Ge buffer, t match with old restored Ge amp. Just to stay in a same "mood"...)
Westrex 2404-C Germanium Amp Restored
But I dont have experience how to transcribe to Ge. Biasing and other things. I am from vacuum tubes world mostly. :(
...
I will try to find some AC127/8
.
I have next Ge-s
.
Type Designator: 2G339
Normally replaceable-slightly different: AC127
Material of Transistor: Ge
Polarity: NPN
Maximum Collector Power Dissipation (Pc): 0.15 W
Maximum Collector-Base Voltage |Vcb|: 15 V
Maximum Collector-Emitter Voltage |Vce|: 10 V
Maximum Emitter-Base Voltage |Veb|: 2 V
Maximum Collector Current |Ic max|: 0.3 A
Max. Operating Junction Temperature (Tj): 100 C
Transition Frequency (ft): 5 MHz
Forward Current Transfer Ratio (hFE), MIN: 150
Noise Figure, dB: -
Package: TO5
.
Type Designator: 2G381
Polarity: PNP
no datas
.
Type Designator: OC83
Material of Transistor: Ge
Polarity: PNP
Maximum Collector Power Dissipation (Pc): 0.6 W
Maximum Collector-Base Voltage |Vcb|: 32 V
Maximum Collector-Emitter Voltage |Vce|: 20 V
Maximum Emitter-Base Voltage |Veb|: 3 V
Maximum Collector Current |Ic max|: 0.5 A
Max. Operating Junction Temperature (Tj): 80 C
Transition Frequency (ft): 0.4 MHz
Collector Capacitance (Cc): 100 pF
Forward Current Transfer Ratio (hFE), MIN: 40
Noise Figure, dB: -
Package: TO1
...
thanks again
cheers
.

Zoran 24th December 2018 05:19 PM

A have also
AC187-AC188

Zoran 24th December 2018 05:24 PM

I found some datas for small Ge already have
.
Type Designator: 2G381
Polarity: PNP
Maximum Collector Power Dissipation (Pc): 0.25 W
Maximum Collector-Base Voltage |Vcb|: 20 V
Maximum Collector-Emitter Voltage |Vce|: 20 V
Maximum Emitter-Base Voltage |Veb|: 3 V
Maximum Collector Current |Ic max|: 0.5 A
Max. Operating Junction Temperature (Tj): 85 C
Transition Frequency (ft): 1 MHz
Collector Capacitance (Cc): 50 pF
Forward Current Transfer Ratio (hFE), MIN: 75
Noise Figure, dB: -
Package: TO1

keantoken 25th December 2018 11:45 AM

Try it with the AC187/188. The 2G339 is fast but the Vce limit is not quite where I would like it to be.


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