Thanks for notifying. Pity to plan EOL, its a very good high voltage PNP transistor. Linear and fast. Used as VAS stage in good amplifiers too. They also plan EOL its NPN mate the KSC3503DSTU I see. They are both available for a while, we better buy some.
MJE350 works there but in general its not as linear or as fast. Not sure if it has an audible impact in this application.
This nice simple circuit has low output impedance for the audio range and above with no peaking at high frequencies.
It does however have some temperature dependency on the output voltage as it depends largely on the Vbe of Q4 for a reference.
The Vbe of Q4 is pretty temperature dependent.
I see 239.72V @ 20C to 223.88 @ 40C for output voltage.
You could make the case this is a good trade off for the simplicity, low output impedance and fast speed it provides as long as the down stream circuit can tolerate the voltage drift with temperature.
It does however have some temperature dependency on the output voltage as it depends largely on the Vbe of Q4 for a reference.
The Vbe of Q4 is pretty temperature dependent.
I see 239.72V @ 20C to 223.88 @ 40C for output voltage.
You could make the case this is a good trade off for the simplicity, low output impedance and fast speed it provides as long as the down stream circuit can tolerate the voltage drift with temperature.
Thanks for your point of view. Because tube audio circuits B+ is usually tolerant for absolute value I kept it simple. Called simplistic reg after all ;-)
We usually set Vout for when warmed up. Nevertheless if drift must be counteracted, a PTC over a Vref resistor of this circuit could possibly help.
We usually set Vout for when warmed up. Nevertheless if drift must be counteracted, a PTC over a Vref resistor of this circuit could possibly help.
That's impossible to determine without practical experiment. Each build having different CCS setting, Vout, sink size, room temperature, enclosure size, or open mounting etc. R9 & R10 are large value. High voltage PTC now I see are not available in large enough Ohmic values, but you could alternatively try a 2k NTC instead of R12. So as the temperature goes up the JFET CCS is degenerated less, sending little more current to the Vref resistors. To counteract downward drift. If it undercompensates try smaller value. If it overcompansates try higher value. And so on and so forth until steady enough from cold to warm.
Salas there are a lot of versions of your shunt regulator circuit in this thread each with different strengths, component types and limitations.
Everyone is interesting.
Nice to see the mostly lost art of designing with only basic parts (R,C,D,Z,Q,etc) demonstrated at a high level of performance.
Be so nice if there was a way to separate each circuit version in a thread so late comers could understand quickly that there is not one or two interesting circuits but many to be found in a thread.
Not sure how the forum could provide a way to easily find each circuit version in a thread. Perhaps as simple as starting a new thread but then the thread would become broken and lost. Bit of a puzzle.
Anyway thanks for the brain food those discreet designs result in.
At least there are links in post#1 to the two most representative versions
Salas,
-It's normal when I set SSHV2 CCS max. is 71mA when R-Core power tx is 0,3A rated, I need 90mA for load + 20mA SSHV2 self consumption?
-Also it's normal PSU B+ without SSHV2 or nothing connected 350V but when I connect SSHV2 and set for output 220-250 Vout there is only 5V of difference Vin & Vout of SSHV2?
-It's normal when I set SSHV2 CCS max. is 71mA when R-Core power tx is 0,3A rated, I need 90mA for load + 20mA SSHV2 self consumption?
-Also it's normal PSU B+ without SSHV2 or nothing connected 350V but when I connect SSHV2 and set for output 220-250 Vout there is only 5V of difference Vin & Vout of SSHV2?
Hi, max ccs setting is a matter of Q2 DMOS idss at VDS provided by Q1.
I don't know if your B+ raw also has CRC with big R and loses much voltage when loaded?
I don't know if your B+ raw also has CRC with big R and loses much voltage when loaded?