5V is a minimum for Vdrop, to ensure the CCS is actually managing to control the current to a constant value.
This worst case occurs when Mains is at lowest supply voltage.
Expect normal mains to be around 5% to 10% above the minimum.
In this situation the "normal Vdrop" will be >=7Vdc.
I have ~12Vdc for Vdrop at 240Vac supply. @ 216Vac supply it will be much lower (~9.5Vdrop).
This worst case occurs when Mains is at lowest supply voltage.
Expect normal mains to be around 5% to 10% above the minimum.
In this situation the "normal Vdrop" will be >=7Vdc.
I have ~12Vdc for Vdrop at 240Vac supply. @ 216Vac supply it will be much lower (~9.5Vdrop).
That's a good one... Salas are you really sure?
Yes its sufficient for stability given its the low end with mains play. More is good for less parasitic capacitance bcs the MOSFET shows less with higher VDS but its counter productive heat wise in serious hotrod.
That's a good one... Salas are you really sure
Sometimes I wish there was a "like" button on DIYA.
So, I finally upped the bias to around 600 ma. The difference on first listen is striking! The only word that I can think to describe the sound is "authoritative".
I am just using cheap cement resistors, but I really prefer this to the 10 ohm dale. I am really happy with this change
It does not compare to the wima to Teflon change. That was also significant, but this is a bigger change in my system.
I used one 2.5 and one 3 ohm resistor to balance the current. I never thought it could get that much better, but it has.
Thank you Salas.
I am just using cheap cement resistors, but I really prefer this to the 10 ohm dale. I am really happy with this change
It does not compare to the wima to Teflon change. That was also significant, but this is a bigger change in my system.
I used one 2.5 and one 3 ohm resistor to balance the current. I never thought it could get that much better, but it has.
Thank you Salas.
Just finished putting mine together.... quite a record, 1 month only!
Can someone recall me the tests I should do?
* V+/V- , test points on PCB (yet done, getting 10.03 on both rails!)
* voltage across the 5W resistors
* DC out - test point on pins.
* ...?
What measures should I get by the last ones?
PS: I'm using two 25VAC-17V.
Can someone recall me the tests I should do?
* V+/V- , test points on PCB (yet done, getting 10.03 on both rails!)
* voltage across the 5W resistors
* DC out - test point on pins.
* ...?
What measures should I get by the last ones?
PS: I'm using two 25VAC-17V.
Thanks Salas! I'm getting 0,9mV/2.2mV . Good enough? I don't think that 1,3mV is somehow noticeable.
PS: on resistors, I get 1,7V and 1,82V ; 10,03V on positive, 10,04V on negative ... I'd expect a more "resemblant" DC offset.
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Its absolutely passable. If you won't bother moving the existing units at the audio quartet 2SK170s mutually in each pair to get -(minus) offset just for academic compliance to such happens when the tiny stronger Jfet sits on top of each pair properly, then you are already done.
mmm... well, I think I'll let them were they are now...!
Maybe I'll tweak it one day. I'll start the chase for the 20k pot!
Thanks again!
This question and response was posted on the Wushuliu build guide some time ago. I'm not certain that the response was unambiguous. Could someone please clarify whether one should go by the square hole/round hole orientation of the LED's or follow the round circle with flat side icon for LED placement?
Mark
Wushuliu,
There is something a little confusing about this board. Look dead center where the 10 LED's are installed (5 LED's per rail). I remember you saying that the flat back corresponds with the cathode or shorter lead of the LED. I also noticed that the LED's have a square hole side and a circular hole side. You'll see that the square hole for the 3 LED/rail section corresponds with the cathode, but this doesn't seem to be true for the 5 LED/rail side. So is the pictograph of the LED accurate or is it the hole shape that is accurate to designate which way the LED's should be mounted?
Anand.
Hi Anand, as confirmed on diyaudio, I followed the pictograph. When I tested the board, all LEDs lit and voltages were matched within spec...
Logged
Mark
Wushuliu,
There is something a little confusing about this board. Look dead center where the 10 LED's are installed (5 LED's per rail). I remember you saying that the flat back corresponds with the cathode or shorter lead of the LED. I also noticed that the LED's have a square hole side and a circular hole side. You'll see that the square hole for the 3 LED/rail section corresponds with the cathode, but this doesn't seem to be true for the 5 LED/rail side. So is the pictograph of the LED accurate or is it the hole shape that is accurate to designate which way the LED's should be mounted?
Anand.
Hi Anand, as confirmed on diyaudio, I followed the pictograph. When I tested the board, all LEDs lit and voltages were matched within spec...
Logged
You might also want to use a bulb tester for safety and peace of mind. That is, wire a conventional incandescent light bulb in series with the primary. It should briefly glow brightly then drop in brightness to a dim glow (unless maybe you've hotrodded it a lot!). A steady bright glow indicates a short somewhere. This can save you the hassle of blown fuses, and the heartache of blown semiconductors. Search the web for "dim bulb tester".
Get a standard electrical octagon box and mount a cheap light fixture. Mount a standard outlet in a standard rectangular outlet box. Use a molded 3-wire AC cord and plug, ground the boxes, wire the outlet and light fixture. You are good to go and safe as can be as long as everything is wired properly and the boxes are earthed. You might want to mount the boxes on a piece of plywood or something so they don't tip over. Other than that I can't think of any issues, except this: We are dealing with potentially lethal voltages! If you have never wired an outlet, find a friend who has, read books or online articles, and triple check everything before you plug it in.