Why a heater should be referenced to the signal ground and not to the power ground? Or say the power return if its floating.
Clue you asked about checking Q6: My Q6 measures about 80 Ohm across its outer legs when in circuit. That is the RDS of a JFET (internal resistance).
I need to check the zeners, but I thought I had to do that with at least one leg de-soldered. I may try that tonight. I'll let you know. Not sure about the heater reference to signal ground. I'm hoping for some enlightenment from KevinKR on that.
Yes you need get them out of circuit somehow first. Better remove the Zeners all together if in doubt. What about Q6 Ohms?
Q6 reads about 4 ohms across outer legs in circuit. Guess I need to pull that and test a little more. Haven't tested the zeners yet as I was cleaning my bench of other small projects.
Q6 NJFET is most probaby gone. 4 Ohm is too low RDS for its type, unless something almost shorted parallel to it causes that reading. So test it again out of board for RDS with DMM across its outer pins. If that will read several tens of Ohms, measure it for IDSS also.
(http://www.diyaudio.com/forums/pass-labs/228897-jfet-matching-sorting.html#post3347479)*
*A 9V battery will also do if not having 11V
(http://www.diyaudio.com/forums/pass-labs/228897-jfet-matching-sorting.html#post3347479)*
*A 9V battery will also do if not having 11V
Hello,
I am thinking of upgrading my EL802/6P45S tube SET with these regs - maybe the driver stage first. I am curious about the effects this reg does compared to unregulated, but well filtered power supply. Can someone share?
I am thinking of upgrading my EL802/6P45S tube SET with these regs - maybe the driver stage first. I am curious about the effects this reg does compared to unregulated, but well filtered power supply. Can someone share?
Over specs supply
Hello Salas,
Would you mind to tell if it's possible to go up to 540VDC output with some mods or would it need deeper mods out of this project scope ?
Current drawn would be 40mA per channel, one for both if possible.
Edit : Forgot to tell it's a negative supply, the positive one is 350VDC, regulated too.
Thanks for your help
Laurent
Hello Salas,
Would you mind to tell if it's possible to go up to 540VDC output with some mods or would it need deeper mods out of this project scope ?
Current drawn would be 40mA per channel, one for both if possible.
Edit : Forgot to tell it's a negative supply, the positive one is 350VDC, regulated too.
Thanks for your help
Laurent
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Tighter sound with more resolution due to much lower impedance than passive ripple filtering, much cheaper, less reliable than passive when mishandled.
Can use higher VDS NDMOS but there are no PDMOS, the polarities sections must be stacked to appear negative also. Wider creepage distances and cuts must be used in the layout to avoid arcing, the ref resistors must be scaled up, the BJTs must be sinked.
Thanks Salas, in other words that would need to study and route a new board.
Would IRFBC40 be able to replace IRF840 ? What about DN2540, do they need each to widstand the max voltage ? Say 600v ?
I'm not that used to transistor electronics, feel more comfortable with tubes.
Laurent
M1 (top one) withstands the HV. There are some IXYS that withstand much high voltage but slower. IRFBC40 is a 600V device which comes close to 840 other characteristics. To surely know that an HV regulation device with changes will work reliably at 540V its not an off hand prediction, it takes experimentation and testing. Small things even like how and where you put any protection like zeners may cause it to blow.
I guess you're right, such a fast and dead silent regulator board might be prone to oscillate during modification process. I may give it a try later on if and when this schematic is fully understood, which is not the case yet. Dissipation is another trade off, I might also concentrate the shunt regulation only for the stages that deserved it best.
I'll stick for the moment with my crappy series regulators.
I 've some other work to do with a few Reflector D to order and a DAC to set up. Thanks Salas for all the work.
You could try the higher VDS devices and higher Vout with an existing SSHV2 board if curious and super careful to see what happens, its just not tested for 540VDC out and alternative parts. I would leave the zeners out and use bigger output sink and good insulation in such a test. The mA setting must be conservative, just covering the full sinewave swing in mA of the load plus 20mA spare. M1 should have equal or higher Vgs (off) than M2 to allow enough CCS flow. The usual DN2540s cascode for 400V spec SSHV2 tops out at circa 110mA on the test bench. I wouldn't aspire to cover an output stage, and would surely start with a dummy resistive load, also some kind of soft starting for DCin like an RC or a variac.
I think at the expense of an additional board and if you have double secondaries (isolated) you can stack two regulators (in serial) to overcome the voltage limit.
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Thanks for the tips, just ordered 2 of the boards. I'll keep that aside for at least a few monthes.
Need first to set up back my electronic workplace, then cook the Soekris ladder DAC that will hopefully be a serious source, and finally go further on a tube amp development started some ten years ago. I'll keep the thread posted in case of success.
Technically that would work. I used that when in an urgent need to try a new idea. I'd like to find a more elegant way for a "final" version. Thanks anyway.