There are even worse fakes than ending up with relabeled enhancement mode MOSFETs. I have seen supposedly IXYS Depletion TO-220 bought from e-bay by other people then asking me why isn't biasing and finally proving NPN transistors of very low HFE in a component tester. 👎
Easiest way is to check it on a cheap component tester. Traditional electrical way is of course Depletion gives full IDSS at 0Vgs like when testing a JFET on breadboard. But usually much more current than a JFET.
DMM way should be there is RDS resistance to measure between drain and source of a depletion and infinity for enhancement but I should check this thought later on a couple of Mosfets to see if valid.
DMM way should be there is RDS resistance to measure between drain and source of a depletion and infinity for enhancement but I should check this thought later on a couple of Mosfets to see if valid.
No. Using Ohm auto scale. I just confirmed. Between pins 2,3 i.e. Drain & Source of a DN2540 (depletion) reads 12Ω. No matter if red probe or black probe where. But on an IRF640 (enhancement) red on D and black on S reads infinity. If reversed probes 7.2 MegΩ.
Yes DN2540 measures 12ohms between Drain & Source, no matter how the probes are connected. Mine IXTP01N100D measures 50 ohms no matter probes are connected so is a Depletion Mosfet hurra/ζήτω!!!
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What's the VGS of IXTP01N100D because in the datasheet I read VGSX Continous +-20V and VGS(off) min. -2.0V & max. -4.4V?
So (not for SSHV2) if I use a cascode CCS as anode load with two IXTP01N100D set to 20mA @ 25º C it's aprox. -1.9V right?
Yes, about. Although the Mosfet will usually work hotter. Somewhere between the 25 and 40C curves meet 20mA more probably.
Hello all,
first of all I would like to apologize for my language. Almost all month I have been reading this long thread about Salas shunt regulator and was very impressed by it. Well, I hoped to find Allen Wright Super regulator schematics but I realized that I am too late by more than 10 years 🙁 My attempts to find The Tube Preamp CookBook were unsuccessful 🙁 But I found Salas SSHV2 and built it. First run and no fire, no explosion everything just perfect. First test was with a dummy load of 15k resistor, current settings 15mA +20mA, voltage In 280V, out 260V. IRF840 temperature is about 45C after a 2 hours run. I slightly modified the PCB board to accept the SMD 2SK880 Q6 transistor. Added some pictures.
But I have a few questions despite reading the whole thread. I understand that on the SSHV2 output there should not be any inductor or capacitor load. Does it mean that I should remove all filter capacitors on the phono stage? There are two 100uF electrolytic bypassed with 2.2uF PP. I added a picture of the modified Klimo LAR schematic just for MM cartridges.
The second question is about input DC. I understand that raw DC after CRC or CLC filter to minimize ripple is ok but can I feed it with regulated DC like in another picture? This regulator with constant current source is taken from LencoHeaven forum member Jessica and it also works very well. Or is it excess filtering?
Thank you in advance for your comments.
first of all I would like to apologize for my language. Almost all month I have been reading this long thread about Salas shunt regulator and was very impressed by it. Well, I hoped to find Allen Wright Super regulator schematics but I realized that I am too late by more than 10 years 🙁 My attempts to find The Tube Preamp CookBook were unsuccessful 🙁 But I found Salas SSHV2 and built it. First run and no fire, no explosion everything just perfect. First test was with a dummy load of 15k resistor, current settings 15mA +20mA, voltage In 280V, out 260V. IRF840 temperature is about 45C after a 2 hours run. I slightly modified the PCB board to accept the SMD 2SK880 Q6 transistor. Added some pictures.
But I have a few questions despite reading the whole thread. I understand that on the SSHV2 output there should not be any inductor or capacitor load. Does it mean that I should remove all filter capacitors on the phono stage? There are two 100uF electrolytic bypassed with 2.2uF PP. I added a picture of the modified Klimo LAR schematic just for MM cartridges.
The second question is about input DC. I understand that raw DC after CRC or CLC filter to minimize ripple is ok but can I feed it with regulated DC like in another picture? This regulator with constant current source is taken from LencoHeaven forum member Jessica and it also works very well. Or is it excess filtering?
Thank you in advance for your comments.
@Sarunas
Congratulations for your working customized build.
-Load side RC cells are OK because R "buffers" C and the shunt reg's output doesn't see a strongly capacitive phase shift.
-The LT3092 is used just for the Vref leg to increase its PSRR I guess. In any case a pre-reg can increase the total ripple rejection of the chain. Given that pre-reg and post-reg won't oscillate as a system and there are audible gains to be had. You already put R13 C3 RC film that isolates and filters RAW to a point. Because sometimes less is more, apply options and compare.
Congratulations for your working customized build.
-Load side RC cells are OK because R "buffers" C and the shunt reg's output doesn't see a strongly capacitive phase shift.
-The LT3092 is used just for the Vref leg to increase its PSRR I guess. In any case a pre-reg can increase the total ripple rejection of the chain. Given that pre-reg and post-reg won't oscillate as a system and there are audible gains to be had. You already put R13 C3 RC film that isolates and filters RAW to a point. Because sometimes less is more, apply options and compare.
Guys, thank you for comments. I will try this simply regulator before SSHV2 to see how it works. Just worrying about extra 20mA for Mosfet. Almost no space for radiator on my PCB. But as Salas said, sometimes less is more. But if I will remove electrolytes from phono stage, that should be an improvement?