Thanks All - 2SK170BL can't be bought in the UK (discontinued), so ebay is the only source; very expensive, and dubious about claims of being matched pairs, etc.
Mmm, it appears we have a language problem here. Well, they will find their way to DIYers anyway...
Another question for you. I want to implement a safety loop breaker circuit, as per the ESP design, principally to preempt any ground loop hum that may or may not be present, but also to protect against any major faults in the power supply. Where on the board is the best zero volt line location that I could connect this?
Thanks Salas.
Just to make sure I properly understand, that would mean 3 wires to the CT position - 2 from the transformer, and 1 wire for the protection circuit?
Just to make sure I properly understand, that would mean 3 wires to the CT position - 2 from the transformer, and 1 wire for the protection circuit?
Yes. You may even solder the wire for the protection underneath the PCB at the connector's middle pin pad if you will feel that the screw isn't grabbing all three wires securely.
I would like to use a Teensy contoller for digital input selection and volume control. Curious if anyone has done this already?
I just received eight pieces of 2SK170BL JFETs
I have 8 pcs with following values
Rds -> 63 Ohm
Vgs -> -0.52V
Id -> 8.08 mA
IMHO this should be fine. Just double checking. Will post pictures afterwards.
I have 8 pcs with following values
Rds -> 63 Ohm
Vgs -> -0.52V
Id -> 8.08 mA
IMHO this should be fine. Just double checking. Will post pictures afterwards.
What have you measured?
When is Vgs=-0.52V?
When is Id = 8.08mA?
I presume not at the same time.
I see that 0.52V / 0.00808A = 64.4ohms. Very close to your 63ohms.
What is your 63ohms?
Hi Andrew, thanks for your reply. Wasn't sure if anyone is still following this thread 😉
I haven't measured them myself. I got the matched quad form ebay. Additionally to matching them, the guy selected them within a Idss in the range of 8 - 10 mA.
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If Idss = 8mA to 10mA, then that is at Vgs=0volts and Vdc=10Volts and Tj=25°C
That does not explain what they meant with telling you Vgs=0.52V
Were they trying to look knowledgable, or trying to confuse the buyer, or they don't have any clue about the product they are selling.
Two measurements you can make are an approximation to Idss and Vpinch-off.
Do those and find out what you really have.
That does not explain what they meant with telling you Vgs=0.52V
Were they trying to look knowledgable, or trying to confuse the buyer, or they don't have any clue about the product they are selling.
Two measurements you can make are an approximation to Idss and Vpinch-off.
Do those and find out what you really have.
I would have expected around 35 Ohm RDS from that IDSS range K170BL. Measure them with the DMM in resistance mode across drain to source and post a close up picture of them please.
i have already soldered them. i have another quad with the same characteristics. should i unsolder them or measure the other quad?
the pictures with measurements of the second quad can be found in this album
https://goo.gl/photos/dSuqmfNVjpjmtoug8
https://goo.gl/photos/dSuqmfNVjpjmtoug8