F5 with 2SK2013/2SJ313

Status
Not open for further replies.
Jump to Latest
#604
permaneder said:
6.3mm spades are long-time reliable connectors. I do use them in my amp builds since more than 30 years without any failure.

There must be good reason, why they are applied in extremely demanding automotive applications, for example.
...
Click to expand...

I overlooked this post but I have to get back to it since the claims it contains are false and dangerous.

I'm in electronics for more than 30 years too. I used to repair very expensive equipment - 10KW SW radio transmitters and injection molding machines, to name some.
Many failures led back to removable connections gone bad.
Simply put, it's inferior way to make the electro-mechanical connection. It's just a way for manufacturing company to make more money during the after-sale period through increased maintenance demands.
With time passing that kind of connection becomes loose, oxidation builds up, the resistance of the joint increases (and it's not small to begin with), where high voltage is present arcing quickens the deterioration.
Of course, those thingies are convenient but there is a price to be paid for that.
So stay away from that crap or accept inferior results and failures waiting to happen.
 
#605
not sure they are that bad
but there are so many brands, types, and slightly different sizes
it is almost impossible to get the right ones that fits properly
and weird listing by supplier is not making it any easier

I gave up
instead it will be heavy duty 15A(amp) print connectors with 3mm mounting screw 😀
 
#607
some wire connections are great for soldering, and some not

actually, before this I have always soldered all my connections

I only hope these are a bit better that the commonly used crappy print connectors
but ofcourse these are only intended for power supply connections
 

Attachments

  • IMG_1252.JPG
    IMG_1252.JPG
    129.8 KB · Views: 1,094
#610
tinitus said:
some wire connections are great for soldering, and some not

actually, before this I have always soldered all my connections

I only hope these are a bit better that the commonly used crappy print connectors
but ofcourse these are only intended for power supply connections
Click to expand...

I've used these Keystone connectors for years. They make a wide variety,
up to 30A rating. It makes a very solid connection right to the pcb.
 
#611
Hi Juma,

I attached 3 of Yours schematics. I want to build headphone amp based on 2SJ313/2SK2013 @ 200mA +-15V based on schematics 3. Because of unobtanium JFETs, it will be very nice if I can use BJT front end, just like on schematics 1 and 2, but that schematics are for different output devices.
So schematics is topologically identical as schematics 3, only Q5, Q6 are BC550/560 , and wanted bias current of output FETS (2SJ313/2SK2013) is 200 mA.

Doable?

Many thanks in advance.

PS

Link to PCB work in progress
 

Attachments

  • Juma1.jpg
    Juma1.jpg
    31.1 KB · Views: 952
  • Juma2.jpg
    Juma2.jpg
    29.8 KB · Views: 949
  • Juma3.jpg
    Juma3.jpg
    34.5 KB · Views: 933
#612
sikahr said:
...Doable? ...
Click to expand...
Sure, see attachment.
This way we avoid JFETs and big caps in the feedback loop.
Q5-8 form CCSs (about 1mA) that supply the input buffer (Q1,2) which polarizes Q3,4 (about 3mA).
Output stage doesn't need thermal compensation (due to relatively high value of R16,18). Just take care to provide enough heatsinking for the output MOSFETs (each dissipates about 15V x 0.2A = 3W ) so that temperature on them doesn't rise to more than 15-20 degrees Cels. above ambient.
You can use bc550c/560c or similar on all positions.
Bias setting procedure (P1,2) is the same as for F5 - set the voltage drop over R16,18 to 660mV for Id=0.2A.
The value of freq. compensation caps (C1,2) can be adjusted for best square wave response and stability. Power rail bypass caps (100-1000 uF) can be added if they don't influence stability (that will depend on your build, PSU and the parts used).
 

Attachments

  • h1.gif
    h1.gif
    9.4 KB · Views: 925
Status
Not open for further replies.
Top Bottom