The CCS moonbird is talking about is the diyaudio/pinkmouse ring of two, on top of a 5687. The one specified is more than adequate for the intended application and anything more is a waste of components.
I have found the LM317 to work very well as cathode sinks in designs with low output impedance. They are not adequate in themselves for plate loads though.
Shoog
I have found the LM317 to work very well as cathode sinks in designs with low output impedance. They are not adequate in themselves for plate loads though.
Shoog
When building CCSs from MOSFETs there are improvements to be found by raising the bias voltage used to set the current. Higher bias voltage allows the current set resistor to be a larger value for a given current. The larger value of current set resistor improves things in 2 ways.
1. local feedback loop works better resulting in better performance
2. Noise from the CCS is reduced
In casode MOSFET CCSs increasing the bias voltage applied to the upper MOSFET improves the operating conditions of the lower MOSFET greatly. Look at the capacitance curves of your chosen MOSFET and note how much the internal capacitance increases at low voltage.
To see some CCS designs using enhancement mode MOSFETs and performance measurements of my CCS designs and some of the commonly used depletion mode MOSFETs take a look at my webpage.
PimmLabs
1. local feedback loop works better resulting in better performance
2. Noise from the CCS is reduced
In casode MOSFET CCSs increasing the bias voltage applied to the upper MOSFET improves the operating conditions of the lower MOSFET greatly. Look at the capacitance curves of your chosen MOSFET and note how much the internal capacitance increases at low voltage.
To see some CCS designs using enhancement mode MOSFETs and performance measurements of my CCS designs and some of the commonly used depletion mode MOSFETs take a look at my webpage.
PimmLabs
Expanding on mach1's comment;
Use " site:diyaudio.com [search terms] " in google and it will return only results from the diyaudio.com domain. Enables searching of ""'ed strings etc.
Use " site:diyaudio.com [search terms] " in google and it will return only results from the diyaudio.com domain. Enables searching of ""'ed strings etc.
Thanks much!
Thanks so much to all for the wealth of info and pointers. 😀
For those reading this thread to learn, here is a terrific thread that explains the inner workings:
http://www.diyaudio.com/forums/tubes-valves/72274-ccs-how-actually-works.html
Thanks so much to all for the wealth of info and pointers. 😀
For those reading this thread to learn, here is a terrific thread that explains the inner workings:
http://www.diyaudio.com/forums/tubes-valves/72274-ccs-how-actually-works.html
as far as i understand it......you can use CCS in place of anode plate resistors and some types will improve the dynamics within a frequency range.
i was wondering if anyone knows of types that work well in the bass range used in this way.
i was wondering if anyone knows of types that work well in the bass range used in this way.
they don't improve dynamics directly - they alter the operating characteristic of the circuit (in comparison to a resistive or inductive load) such that the tube operates with an effectively horizontal load line. Depending on the rest of the circuit, this may allow for "improved dynamics".
I found Gary's explanation to be really useful...
I found Gary's explanation to be really useful...
would this not change dynamic/range (gain through out) dependant on where you place the new load line in comparison to one set by a resistor if switched from one to the other.
yep - typically it widens the range. The resistor HAS to alter its loading depending on the current passing through it - that is shown graphically by the angle of the load line. A CCs doesn't, and so typically spans a wider area of the anode characteristics. The implication of this is that, under the right circumstances, it will produce output closer to the theoretical Mu of the tube, and so this can be exploited to produce a wider (or deeper) dynamic range.
Of course, this assumes the rest of the circuit is up to it...
Of course, this assumes the rest of the circuit is up to it...
I don't know if the rest of the circuit is up to it.
but it may make a strange pre amp if I don't blow myself up first.
~(ecl82 275dcv fully insulated)
I HAVE A DREAM
but it may make a strange pre amp if I don't blow myself up first.
~(ecl82 275dcv fully insulated)
I HAVE A DREAM
Are there any difference between TMJE340 and MJE340? Cant seem to spot any from the datasheets. Thanks.
Hi, which are the criteria to decide for the use of a mosfet cascode CCS (like the two DN2540 by Sy) or a Gyrator, single DN2540, as proposed by Revintage (or was Wabebourn?)
I mean on the plates of a tube input stage, for example
Are these two solutions compatible with the use of led biased cathodes?
Thanks
JJT
I mean on the plates of a tube input stage, for example
Are these two solutions compatible with the use of led biased cathodes?
Thanks
JJT
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It's on my web page. Lower left edge under presentations. "CCS's and signal current control".
The CCS performance measurements are located in the Current Sources area at the upper left edge.
I put this together for a presentation at the "second annual bay area tube festival" several years ago.
Gary
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