• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

CCS for tubes/valves: PCBs

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#144
I think there is a minor error either on the NPN high voltage print board or on the schematic in post #6 in this thread.
On the NPN HV print boards (at least the batch I’ve got) the power transistor MJE340 is marked Q2, but in the schematic the MJE340 is marked Q1.
(The same error is done for the NPN low voltage circuit (Q1=Q2) but at here the transistors are the same type (BC549C))


Print board layout:
http://www.diyaudio.com/forums/attachment.php?s=&postid=829061&stamp=1138453582

Schematic:
http://www.diyaudio.com/forums/attachment.php?s=&postid=829231&stamp=1138481795

No problems - just a little bit confusing. 😉

Jan E Veiset
NO-6600
 
#148
#152
It is time to move on this.

I'd like to get more comments from those that got proto-type boards.

Some of the comments i did get indicated that some board design would be worthwhile. The disadvantage of doing so would be a higher cost board.

A summary of the comments:

Pads are too small.
Holes are too small.
More versatility required for the variable resistor.
Be nice if the holes were plated thru.
Be nice if the real-estate the board takes up was smaller.

dave
 
#153
Be nice if the real-estate the board takes up was smaller.
Click to expand...

Just an idea. If you mirror everything the transistor can be rotated 180°. By doing this it can bend down to fix it to the chassis (cooling). The overall dimensions are 40mm by 25mm, for this size board two mounting hole are more than sufficient I think. I don't know if it is possible to do this setup with all the boards.
This is just a quick moving around of the parts, I don't know if Q1 is possioned correctly!

Regards
 

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#155
Personally I don't see a need for plated thru holes because it makes it hell to remove a part if one needs to unless you have a desoldering station. I have (4) of them and I still don't like plated thru.

Why not one board that can do any of the three functions? Bigger holes don't hurt either for us older folk that don't see like we did when we were in our 40's.
 
#157
Making one board to fullfill all three functions is going to lead to confusion I think.
Click to expand...

We have good people here that are capable of making a good set of instructions.

The positive here is that the boards we purchase will get used up. Personally I would buy more knowing that I can use them all instead of having one type of board on my shelf because I never got around to using one for that function.
 
#159
Morgan Jones advised me against this when suggested as it might lead to capacitive coupling and instability.
Click to expand...

Are you reffering to the placement of Q2 against the chassis?

Why not one board that can do any of the three functions?
Click to expand...

As far as I can see you can use the board for all three functions as long as you pay attention to the polarity of the LED's en the orientation and type of Q1 and type of Q2. For Q2 in the LV CCS you can just bend the legs a bit open.

Regards
 
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