ZenV8 with CCS and Capacitance multiplier!

[steenoe]

I fiddled around with Eagle to try and make a working ZenV8 with CCS and capacitance multiplier/regulated supply. I have used the CCS from the F2 clone and the familiar Zen regulated supply without the zeners. Since my "mentor" Apassgear is travelling around in south-america right now, I would like to have your comments on the circuit, please. I adjusted the railvoltage in the "normal" Zen fashion. Any corrections would be greatly apprieciated I used the P-channel device for the CCS because I have a tube of those, sitting around.

Steen

[steenoe]

For this amp, I made some perf-board modules, for making it easy to test things Here is a pic of the CCS's and the reg's. The zeners in the reg's are not connected at this point Have a look at the CCS's and reg's

Steen

[tschrama]

Hi,

correct me if I'm wrong, but you are using a MOSFET in the your regulator and not a BJT .. so this is not a real capacitance multiplier.. you may need a resistor to ground from the gate of the MOSFET to set a DC-point. The MOSFET draws no gate current, like a BJT draws a base-current, so there's no voltage drop around the gate resistors in your circuit.....

[apassgear]

I’m back Steen, nice to see that you are all out designing some amps now!!! Nice work.

I’m more a hands on when it comes to design something (simple of course) so I’m not much of a help when it comes to theory on a schematic form and I have little experience on cascoding and biasing a jfet, but as you know there are many guys around this forum that are quite capable and will show up with some hints to make a workable amp. Even though we do have ZV8 schema as a reference.

Looks to me that you may need a ground reference to the gate of Q1 just before R1 even though R11 may do to that reference.

If you find oscillations on the circuit you may try moving R10 to the left just prior to the gate of Q5 which will work as a grid stopper, same as Fig 10 on ZV8.

[steenoe]

Thanks a lot for the replies Wellcome home Tony Hope you had a nice trip I will take a look at the things you and Tschrama mentioned Well, I dont know much about designing, to say the least I would just like to build an amp like the schematic posted I know NP will put the ZV9 up on PassDIY next week, but I would like to try this one, too So just let me know if there is more?

Steen

[Nelson Pass]

I'm sure you will be very amused to see ZV9 next week.

[Zen Mod]

steen's multiplier is replicated from Z V3
here is what Papa sez:

"The circuit does not actually require the use of Zener diodes to
work well for many purposes. If you take the Zener diodes out,
then the circuit simply filters out the AC voltage from the supply
value, leaving the DC value and giving a DC output voltage about
4 Volts less than the unregulated voltage. I prefer the value
stability with the Zeners in, as they represent only a small
investment in parts."

'nuff from me for now

[steenoe]

I'm sure you will be very amused to see ZV9 next week.

You made my day, Nelson Thanks a lot

here is what Papa sez:

Just what I was thinking when I draw'ed up the schematic

Steen

[Zen Mod]

Originally posted by steenoe
You made my day, Nelson Thanks a lot
Just what I was thinking when I draw'ed up the schematic

Steen

just little correction in your circ-moved one leg of cap in cascode

regarding ground refference for gate of Jfet- R2 and R11 are in same time part of NFB loop and gnd reference for gate

think toobie

ole sheeeeeeeet with toobz

[steenoe]

That is correct. R2 does not connect to the ground line. It connects only on top of R11. My sch doesnt make that clear
Please keep looking Choky, I want to get all faults corrected

Steen