Roender,
This post advocates using red LEDs instead of green ones. If what this post says is true, could you suggest modifications to your amp to accommodate a change from green to red? Thanks.
http://www.diyaudio.com/forums/solid-state/174157-openloop-gain-compensation.html#post2312737
This post advocates using red LEDs instead of green ones. If what this post says is true, could you suggest modifications to your amp to accommodate a change from green to red? Thanks.
http://www.diyaudio.com/forums/solid-state/174157-openloop-gain-compensation.html#post2312737
Somewhat marketing like annoucements...
This amp is an authentical TWO stages amp ,
providing we count the cascoded differential as
a single stage..
This latter provide 20 db of OL gain, while the
VAS bring the remaining 74db OL gain to reach
the 94db total OLG.
This amp is an authentical TWO stages amp ,
providing we count the cascoded differential as
a single stage..
This latter provide 20 db of OL gain, while the
VAS bring the remaining 74db OL gain to reach
the 94db total OLG.
The LED's set the base/emitter voltage. To maintain the specified current, just change the emitter resistor along with the LED.
Sheldon
and measure the current through the resistors to check it matches the design value.
This is where builders can benefit from three builders' schematics.
Basic to understand the circuit.
Voltage values added for error checking.
Current values added for error checking.
Most solid state circuits depend on current values through various components to determine overall performance.
If this information is missing then the builder never knows if his clone matches the Designer's Performance Targets
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Hi.
Does anybody know if one NJL diode must be bypassed, than perhaps we can use NJW device instead as they have the same die (for one device only)?
Does anybody know if one NJL diode must be bypassed, than perhaps we can use NJW device instead as they have the same die (for one device only)?
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You could do that, but why? BTW, you'd have to redesign the PCB or twist the device leads around - they are not in the same order for NJL and NJW.
Sheldon
They are cheaper and more easy to find when you are going to built HT. NJL types aren't available for now.
Btw, where you found that they are not in the same order. NJW datasheet lack of pin alignment. Maybe in Onsemi forgot about it.
NJW0281/0302
http://www.onsemi.com/pub_link/Collateral/340AB.PDF
Compare it with the datasheets of NJL's with pin alignment.
What are the chances that these are real, as filtering caps for power amp:
2PCS Nichicon KG Gold Tune Audio Capacitor 10000uF/50V [KG Gold Tune 10000uf/50V] - $20.00 : DAC,Audio Amplifier,Hifi Amplifier,Tube Amplifier,Hlly Audio, Hlly Electronics
2PCS Nichicon KG Gold Tune Audio Capacitor 10000uF/50V [KG Gold Tune 10000uf/50V] - $20.00 : DAC,Audio Amplifier,Hifi Amplifier,Tube Amplifier,Hlly Audio, Hlly Electronics
I would very like to build this beautiful amplifier, but I need some advice.
Can I use for RMI-FC 100 amp as J1 and J2 2SK170V or they have to have idss not more than 12mA?
What are pros and cons of using 0.18 ohm emitter resistors for not perfectly matched output devices instead of 0.1 Ohm for matched ones? AS I remember, Mihai told before that another RMI-FC100 amp he made for his friend with not perfectly matched devices sounds the same as with matched ones.
If 1W glass case 1N4148 is not available, can I use 500mW one as D1. Likewise green rectangular LEDs - with 2.2Vf, 20ma (according to datasheet)?
What is the power dissipation of the amp at it's full output power?
To operate the amp at 38VDC for output and 43VDC for front end I need to change only Zener diodes to 41V?
Can I use fast recovery rectifiers for amp PSU?
What value of input capacitor can I put if I need it?
Any support will be appreciated.
Regards.
ZDR,
regarding Nichikon Gold you can ask manufacturer if this shop is their authorized distributor. If not you may get to know where to buy it.
Can I use for RMI-FC 100 amp as J1 and J2 2SK170V or they have to have idss not more than 12mA?
What are pros and cons of using 0.18 ohm emitter resistors for not perfectly matched output devices instead of 0.1 Ohm for matched ones? AS I remember, Mihai told before that another RMI-FC100 amp he made for his friend with not perfectly matched devices sounds the same as with matched ones.
If 1W glass case 1N4148 is not available, can I use 500mW one as D1. Likewise green rectangular LEDs - with 2.2Vf, 20ma (according to datasheet)?
What is the power dissipation of the amp at it's full output power?
To operate the amp at 38VDC for output and 43VDC for front end I need to change only Zener diodes to 41V?
Can I use fast recovery rectifiers for amp PSU?
What value of input capacitor can I put if I need it?
Any support will be appreciated.
Regards.
ZDR,
regarding Nichikon Gold you can ask manufacturer if this shop is their authorized distributor. If not you may get to know where to buy it.
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Does anybody be so kind to help me out?
Do you ever consider to use more superior BF862 or BF861B instead of 2SK170?
Regards.
Do you ever consider to use more superior BF862 or BF861B instead of 2SK170?
Regards.
Nice to see you back Mihai.
Just found today on forum looking for LSK170 as replacement for jfets which also seems to have better specs than 2sk.
For BF862:
V(BR)GSS-20V
Pd-0.3W
IDSS-10~25mA
Ft-715MHz
En-0.8nV/Hz
Ciss-10pF
Crss-1.9pF
Yfs-45mS
For BF861B:
V(BR)GSS-25V
Pd-0.25W
IDSS-6~15mA
Ft-unknown
En-1.5nV/Hz
Ciss-10pF
Crss-2.1pF
Yfs-16-25mS
For 2SK170:
V(BR)GDS-40V
Pd-0.4W
Ft-unknown
En-1nV/Hz
Ciss-30pF
Crss-6pF
Yfs-22uS
People who use BF862 claim it sounds better than 2SK170 and costs today a half of 2SK170.
There is comparison table made by Scott Wurcer, in "B1 JFET alternatives list" thread, post 15.
Regards.
Attachments
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Well, BF862 seems to be a very good candidate to replace k170.
Whit that small SMD (sot23 ?) case it won't be easy to sort them for the same Idss.
Whit that small SMD (sot23 ?) case it won't be easy to sort them for the same Idss.
True, but cheap and in stock at Digikey and Mouser (and probably Euro distributors). Guess one could make a little jig to clamp them to for testing. Note that drain and source are interchangeable too. Only caveat is that it's a 20V part, so not interchangeable for all apps.
Sheldon
Mihai.
What you think about Toshiba 2SK30ATM jfet? It' seems to par with BF862 in NF and Ciss, but has lower Idss and Pd.
Perhaps this can be of help about installing technique of SOT23 package: http://www.diyaudio.com/forums/pass-labs/140488-b1-turbo-chip.html
There is about experience of matching SOT23:
http://www.diyaudio.com/forums/pass-labs/120445-pass-discrete-opamp-dip-8-package-2.html#post1471448
And: http://www.diyaudio.com/forums/pass-labs/141162-2sk170-matching.html#post1785232
What you think about Toshiba 2SK30ATM jfet? It' seems to par with BF862 in NF and Ciss, but has lower Idss and Pd.
Perhaps this can be of help about installing technique of SOT23 package: http://www.diyaudio.com/forums/pass-labs/140488-b1-turbo-chip.html
There is about experience of matching SOT23:
http://www.diyaudio.com/forums/pass-labs/120445-pass-discrete-opamp-dip-8-package-2.html#post1471448
And: http://www.diyaudio.com/forums/pass-labs/141162-2sk170-matching.html#post1785232
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Most important, it has a too low transconductance (gm).
About 1.2mS while the used devices are on the order of 10mS.