Sons of VHex

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#144
still4given said:
Hi Valery,

I'm wondering if where you have the two red LEDs if a 3.3V zener will do the same thing? I have nothing against LEDs, I actually kind of like them, I just wondering.

Thanks, Terry
Click to expand...

Hi Terry,

You're right - a 3.3V zener will do the job. In general, a 1W-rated zener, like 1n4728, allows much higher currents (up to 276mA, according to datasheet), small LEDs are much less powerful (I would not exceed 20mA or so) - I like using them at 1...10mA range of cirrents.

Cheers,
Valery
 
#146
At the same time, one "side effect" of current drive, confirmed by Jeff in his live VHex+ build tests and long term listening experience, is high tolerance to noise/hum. It's difficult to induce some noise with this kind of circuits, where current is what matters, until it's converted into voltage at 5...7 mA quiescent conditions.
 
#147
vzaichenko said:
Hi Terry,

You're right - a 3.3V zener will do the job. In general, a 1W-rated zener, like 1n4728, allows much higher currents (up to 276mA, according to datasheet), small LEDs are much less powerful (I would not exceed 20mA or so) - I like using them at 1...10mA range of cirrents.

Cheers,
Valery
Click to expand...

Hi Valery,

Thanks. I had been wondering about it because on the little quasi amp that Ranchu designed, they use a 3.3V zener and some of us replaced it with a blue LED. I kind of started that because I didn't have a zener of that size in stock and Hugh said I could us an LED in its place. I now have a stock of the zeners so I just though I'd ask.

Thanks again. Terry
 
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#149
Hi Val,
Terry was asking D14- replace to 3,3V zener?
Samuel you soon. Same thought- Juma Pre.
Our German reichelt have in stock SK117- but in wich Idss they should be?
BL/GR (1,2-14mA datasheet)
Next though- change to VLatMos- pull out Q10,11,12 and couple SK/SJ- so
simple possible ? 😛
Can we call IPS now Ampliwire+CP? 😀

Regards
 
#150
Bangla H said:
Hi Val,
Terry was asking D14- replace to 3,3V zener?
Samuel you soon. Same thought- Juma Pre.
Our German reichelt have in stock SK117- but in wich Idss they should be?
BL/GR (1,2-14mA datasheet)
Next though- change to VLatMos- pull out Q10,11,12 and couple SK/SJ- so
simple possible ? 😛
Can we call IPS now Ampliwire+CP? 😀

Regards
Click to expand...

I'm talking about replacing D6/D7 and D7/D8 with 3.3v zeners.
 
#151
Samuel Jayaraj said:
2SK117 is difficult to come by. Why not use one of the modern SMD JFETs? BF862 is easily available but may have to be adapted for this application. There are others as well. Just a thought to make building easier for everyone, across the globe. Thanks.
Click to expand...

Hi Sam, good idea.

I always have some 2sk117 available, so I'm using them with no hesitation. However in most of the world it may be a problem - I will see what I can do with regards to BF862.

Cheers,
Valery
 
#152
Bangla H said:
Hi Val,
Terry was asking D14- replace to 3,3V zener?
Samuel you soon. Same thought- Juma Pre.
Our German reichelt have in stock SK117- but in wich Idss they should be?
BL/GR (1,2-14mA datasheet)
Next though- change to VLatMos- pull out Q10,11,12 and couple SK/SJ- so
simple possible ? 😛
Can we call IPS now Ampliwire+CP? 😀

Regards
Click to expand...

Hi Bangla,

Terry was asking about the LED pairs, just in principle.
I'm using GR, although Idss class is not important in this design, as jFETs are forced to work at the given drain current in CCSed environment.
For lateral output, the best way is just taking the VLatFET OPS configuration (you have the schematic).
Yes, the front-end is a kind of Ampliwire+CP )

Cheers,
Valery
 
#153
Thanks Val for kind reply,
that helps a lot, and second though was right because your CCS to JFet- a stable working point- cool.
I go than looking if i can work and learn on Eagle routing etc. on VLatFet board and still
follow.

Regards..
 
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