I read the resistance should be beyond 300 ohm.
Can I use the schematic in fig 5 http://www.linearsystems.com/assets... The New Frontier Part 1, by Erno Bordely.pdf
Do you have any suggestion for the diodes. I think 1M resistor should be ok also with 9v battery. Right?
You need dual polarity supply, for the Vp voltage (using the 1M0 resistor)
The Id (2mA and 5mA) vs Vgs also need dual polarity supply.
Idss can use single polarity supply.
The Id (2mA and 5mA) vs Vgs also need dual polarity supply.
Idss can use single polarity supply.
yup
Fig. 5
but if you take a look at sch , you'll see that you don't need any resistor - tie S and G , while D is solo
(Idss test is all what you need , at Borbely's sch switch needed for that )
Fig. 5
but if you take a look at sch , you'll see that you don't need any resistor - tie S and G , while D is solo
(Idss test is all what you need , at Borbely's sch switch needed for that )
yes, he asked ;
but we know that he isn't experienced enough to know what's actually needed
more confusion isn't of any benefit
but we know that he isn't experienced enough to know what's actually needed
more confusion isn't of any benefit
here we go again
look (don't use Rs , just ignore it , as 0 Ohm) ;
instead of 12V , you can use 9V battery :
look (don't use Rs , just ignore it , as 0 Ohm) ;
instead of 12V , you can use 9V battery :
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hello
I need som expertice advice ....
Have built a F5Turbo with choke input spu, that´s given me quite a few headaches
it is built as vertical cylindrical mono towers with powertransfomer in the bottom base and a huge vertical heatsink with F5T and cap.bank pcb are mounted
now to the problem
at startup, amp 1 ramps up to 35vdc and about 270mA bias, and then reaches target 350mVand 31,5vdc in about 30mins
amp 2 ramps up to above 38vdc and about 200mA and then uses a good hour to reach target of 350mA
once at target they both get about 31,5vdc from psu and main heatsink temp is about 50C
the powertransformers are 1KVA dual 50VAC into full wave MUR860, Hammond 60mH2A chokes followed by series ARCOL HS1508R on dedicated heatsink and then dual parallelled 400R Caddock bleeders.......
suspect some thing has gone south when startup voltages exceeded 40dc on amp 2, before I got the bleeder in
however both sounds normal
all replies welcome
best
Leif
I need som expertice advice ....
Have built a F5Turbo with choke input spu, that´s given me quite a few headaches
it is built as vertical cylindrical mono towers with powertransfomer in the bottom base and a huge vertical heatsink with F5T and cap.bank pcb are mounted
now to the problem
at startup, amp 1 ramps up to 35vdc and about 270mA bias, and then reaches target 350mVand 31,5vdc in about 30mins
amp 2 ramps up to above 38vdc and about 200mA and then uses a good hour to reach target of 350mA
once at target they both get about 31,5vdc from psu and main heatsink temp is about 50C
the powertransformers are 1KVA dual 50VAC into full wave MUR860, Hammond 60mH2A chokes followed by series ARCOL HS1508R on dedicated heatsink and then dual parallelled 400R Caddock bleeders.......
suspect some thing has gone south when startup voltages exceeded 40dc on amp 2, before I got the bleeder in
however both sounds normal
all replies welcome
best
Leif
Does the bias and offset stabilize when up to operating temperature?
If yes, then everything is probably fine - these amps are always moving until the heatsinks are hot.
If yes, then everything is probably fine - these amps are always moving until the heatsinks are hot.
yes they do, but I don´t see why one is getting to target bias so much faster than the other
and I´ve struggled for weeks with the overshooting voltage at startup with the slow one
was seriously worried for the driver transistors that got above 40v several times
best
Leif
and I´ve struggled for weeks with the overshooting voltage at startup with the slow one
was seriously worried for the driver transistors that got above 40v several times
best
Leif
That is a function of choke input PSU. Replace with resistor and the PSU overshoot will go away.
What does your meter read when the two probes are placed on the lead out wire on ONE side of the resistor?
That reading should be subtracted from the reading you get across the resistor.
For low value resistors, this "correction" makes a big difference.
Simply placing probe to probe misses out a connection. It may read the same as probes on the lead out, it may not. It depends on the resolution of the DMM and the consistency/repeatability of the instrument.
Learn to use your instruments and in particular learn what they are not good at.
Learn how to "compare" REF to DUT. It becomes the most powerful tool you can posses.
We amateurs with limited resources are not good at "absolute" measuring.
eg. I can't measure a resistor to any better then 1%. But I can compare resistors using a variety of methods and get matching to better than 0.02%
That reading should be subtracted from the reading you get across the resistor.
For low value resistors, this "correction" makes a big difference.
Simply placing probe to probe misses out a connection. It may read the same as probes on the lead out, it may not. It depends on the resolution of the DMM and the consistency/repeatability of the instrument.
Learn to use your instruments and in particular learn what they are not good at.
Learn how to "compare" REF to DUT. It becomes the most powerful tool you can posses.
We amateurs with limited resources are not good at "absolute" measuring.
eg. I can't measure a resistor to any better then 1%. But I can compare resistors using a variety of methods and get matching to better than 0.02%
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