Hi Ricardo,
The DOS-CFP page is still under construction, and the schematic only shows the added transistors in the input stage, which is the essence of the CFP version.
The 1k8 resistor may be replaced by a current source. It was added later and can be applied to the original DOS circuit as well. I hope to update it soon with some text on Steve's new board and I will put up a specific schematic of it.
Regards,
Ray
FWIW,
I added the current sink to my board before I ever heard of the CFP. It didn't make any difference. The CFP makes a difference.
Steve
The input stage and output transistor are directly coupled, so any variation of the input stage current will have an effect on the operation point of the output transistor. The current source makes the operating point of the output transistor independent of the input stage. It will set the current to 10mA, whatever the input stage does.
I want to draw a new schematic anyway, so when do, i'll do some simulations with and without CCS, to see if there's less distortion.
Ray
I want to draw a new schematic anyway, so when do, i'll do some simulations with and without CCS, to see if there's less distortion.
Ray
Allready done, check THIS , Figure 15A/B/C and Table 3. And with 0.1mA through JFET's they don't know if they are barely alive or barely dead
Yep, that's also my conclusion, thanks for the link. I did some simulations today, and mainly the second harmonic is noticeably lower when using the FET current sink instead of the 1k8 resistor. Third harmonic was only just a bit lower. Current was set at 10mA, but if you use a trimmer in the current source, all options are open!
Ray
Ray
If you want to set the current at 10mA, the 6.5mA is less suitable. Idss also depends on Vds, but it's unlikely it will do 10mA, even when the source resistor is 0 ohm. You have to experiment a bit. Just insert a 22 ohm resistor to start with, and tune it lower if the desired current is not met. You could end up with a wire, but that's o.k.
Ray
Ray
Dear Friends,
I have a CD 63 SE and wil fry some of the modifications mentioned. One of my pressing problems is the laser lens VAM 12.2 which is presently available mostly chinese one they dont last.ne spare I had last was from malaysia and it sure had some quality.Any place I can get a good laser pickup??
Regards
Ajit
I have a CD 63 SE and wil fry some of the modifications mentioned. One of my pressing problems is the laser lens VAM 12.2 which is presently available mostly chinese one they dont last.ne spare I had last was from malaysia and it sure had some quality.Any place I can get a good laser pickup??
Regards
Ajit
Probably not...admitedly 1500 pages is a lot to read. Try looking at Ray's site (just above, "6h5c") and Roemeister's. That will give you a good idea of where things stand at the moment.It's an on-going process, although it may have been taken as far as is sanely possible. (I hope this is not the case since I also have the 67')
Thanks for the reply 6h5c's site is quite interesting, what worries me is component obscelecence and the possibility of there now being half dozen variants of same componet as much of the information is now 10 years or so old and the information that's there isn't concise enough for some of the mods as some of the information is written such that may only be understood by someome who has already done the mods (possibly why this post is so long), I also worry that some of the opamp upgrades may not be a straight forward swap.
I was amused by a statement at the bottom of Roemeisters site "why spend hundreds of punds on a new player when you can upgrade your existing player" (for hundreds of pounds )
Tom
I was amused by a statement at the bottom of Roemeisters site "why spend hundreds of punds on a new player when you can upgrade your existing player" (for hundreds of pounds
)Tom
Hi all.
What about, Steven, please, about differences between
these 1
and 2
And, what are value of added components ?
Thanks
What about, Steven, please, about differences between
these 1
An externally hosted image should be here but it was not working when we last tested it.
and 2
An externally hosted image should be here but it was not working when we last tested it.
And, what are value of added components ?
Thanks
If that's the board from Steve, I worked out the following component list for the CD67.
Haven't built it yet though.
Left Value
C1, C2 4n7
C11, C12 100nf
C3, C4 1n5
C8 220n
C9, C10 1u5
L1, L2 10mH
R1, R2 2k4
R10 47k
R11 22r
R12 470k
R13 1k
R14, R15 6k8
R3, R4 1k5
R5, R6 4k7
R7, R8 680r
R9 330r
T1, T2 2SK170BL
T3, T4 BC550C
T5 2SK170BL
T6 2SK170BL
T7, T8 BC560C
Pete
Haven't built it yet though.
Left Value
C1, C2 4n7
C11, C12 100nf
C3, C4 1n5
C8 220n
C9, C10 1u5
L1, L2 10mH
R1, R2 2k4
R10 47k
R11 22r
R12 470k
R13 1k
R14, R15 6k8
R3, R4 1k5
R5, R6 4k7
R7, R8 680r
R9 330r
T1, T2 2SK170BL
T3, T4 BC550C
T5 2SK170BL
T6 2SK170BL
T7, T8 BC560C
Pete