Sluckey 6SL7 Tremolo Oscillator for AA764 - Layout drawn, questions on it

[kagliostro]

I've tried to draw a layout of an oscillator for the AA764 based on Sluckey 6SL7 Oscillator


(there is a pair of errors, see the schematic on further post for the correct version)



I think (I hope) the layout is electically corret (please if you see something wrong let me know)

I've 2 rows 30 columns Turret Board (they also have 4 rows of empty holes for additional Turrets if required)

Distance between center hole to center hole is 10mm (on rows and also on columns)

My question is if you have councils to optimize it or if you see the way (adding turrets on the empty holes) to shrink the Layout that now is composed of 11 columns

Thanks

Franco

Attached the .vsd file

[sluckey]

I see a couple small errors. You forgot to run a ground wire to the speed pot. And the ground wire for the footswitch jack is connected to the sleeve "switch" lug. It should be connected to the sleeve lug.

Does the filter cap have to be on the board? Can you just tap into the screen B+ node like the AA764? You lose one column if the filter cap is really located elsewhere.

Is this going to be a separate board just for tremolo? Or is this just part of a bigger circuit? Or is this just a brain exercise?

You might lose maybe 3 more columns if you utilize some of the other rows so that you have two components per column in some areas. Unless space is limited though, I'd leave it be. It's logical and neat as is.

[kagliostro]

Ciao Steve, Many Thanks

I see a couple small errors

Fixed

Does the filter cap have to be on the board? Can you just tap into the screen B+ node like the AA764? You lose one column if the filter cap is really located elsewhere.

The filter cap can be elsewere, I placed it on the board because I was trying to have it the more near possible to the tube that is feeded with it (to have less currents moving around the chassis), my screens are at 250V because the power tube is a 1625 and seemed me that is a low voltage for the oscillator, if is your opinion that I can move the cap elsewhere, I'll move it on the PS board

Is this going to be a separate board just for tremolo? Or is this just part of a bigger circuit? Or is this just a brain exercise?

It is planned to be part of a bigger circuit, but also to be a stand alone oscillator if required by chassis layout;  the brain exercise It will be to draw a version with more components on the columns to reduce the size of what will be possible (but not for this amp)

this is the schematic of the amp



and this the PS



If you have suggestions, I'm here

Work in progress



Grazie ancora

Franco


New .vsd attached

[kagliostro]

Here is the shrinked version, I was able to reduce of 5 columns (now it is 60mm x 60mm), but I don't like it very much because the wires must be connected also on the central row of the board, may be this isn't a problem and circuit function well ??

The central row of the board is placed on new holes, because if the existing holes are used one side distance is 30mm and the other is 20mm, using new holes permit to have 25mm and 25mm of distance from center hole to center hole of the rows





Also here I hope the circuit is OK, and if you see problems, please let me know (Thanks)

I think that this little board can be used also as an add-on to add tremolo to amp that didn't has it

Franco

Here attached the .vsd file

[sluckey]

 

[Jerry garrcia]

Here is the shrinked version, I was able to reduce of 5 columns (now it is 60mm x 60mm), but I don't like it very much because the wires must be connected also on the central row of the board, may be this isn't a problem and circuit function well ??

The central row of the board is placed on new holes, because if the existing holes are used one side distance is 30mm and the other is 20mm, using new holes permit to have 25mm and 25mm of distance from center hole to center hole of the rows





Also here I hope the circuit is OK, and if you see problems, please let me know (Thanks)

I think that this little board can be used also as an add-on to add tremolo to amp that didn't has it

Franco

Here attached the .vsd file

Hi. Did you try the tremolo? The @slyckey designed  I was thinking of adding one to a 5b2 build.

Showed my idea on a FB group and got this answer “Everything looks OK except for the fact that your tremolo intensity control will also affect your quiescent DC bias on the second stage, changing its operating point.
 This would mean that rotation of the intensity control would alter the linearity of the stage even when the tremolo was switched off...
 If your goal was to make a normally clean running stage 'adjustably dirty' then you got what you wanted. But you will have to readjust that intensity knob every time you switch the tremolo on or off....” was this your experience as well?

[sluckey]

Here's my circuit that Franco based his circuit on. Only uses one triode and modulates the grid of the output tube. Probably work well on your SE amp too.

     http://sluckeyamps.com/RCA/Ampeg_J12B.pdf

[Jerry garrcia]

Here's my circuit that Franco based his circuit on. Only uses one triode and modulates the grid of the output tube. Probably work well on your SE amp too.

     http://sluckeyamps.com/RCA/Ampeg_J12B.pdf

Thank you! Do you think a 6SQ7 or a 6SF5 tube would work better than half of a 6SL7 in that circuit? Always sad to not use all the parts in a tube (not including the diodes in the 6SQ7 🙂).

[sluckey]

Do you think a 6SQ7 or a 6SF5 tube would work better than half of a 6SL7 in that circuit?

Since both of those tubes have a gain of 100, either should work better than the 6SL7 (gain of 70).

[Jerry garrcia]

Do you think a 6SQ7 or a 6SF5 tube would work better than half of a 6SL7 in that circuit?

Since both of those tubes have a gain of 100, either should work better than the 6SL7 (gain of 70).

Maybe a 6SQ7 would be better since it has a higher plate resistance of 85Kohm compared to 66K of the 6SF5
And it goes in the coupling cap and the grid stopper of the 6V6? And also about the LED on the cathode of the triode, never used it. Is there some special LED type and the anode of the LED goes to the cathode of the triode and the LED’s cathode to ground?

[sluckey]

And it goes in the coupling cap and the grid stopper of the 6V6?

Is there some special LED type and the anode of the LED goes to the cathode of the triode and the LED’s cathode to ground?

Disconnect the bottom end of that 220K grid resistor from ground and reconnect it to the wiper of the INT pot.

Use a common red or yellow 5mm LED with LED cathode to ground. Red or yellow LEDs provide a good bias voltage for the oscillator tube. Other colors are not so good. I like to mount the LED in a bezel and mount on the front panel to provide a nice blinky indicator.

[Jerry garrcia]

And it goes in the coupling cap and the grid stopper of the 6V6?

Is there some special LED type and the anode of the LED goes to the cathode of the triode and the LED’s cathode to ground?

Disconnect the bottom end of that 220K grid resistor from ground and reconnect it to the wiper of the INT pot.

Use a common red or yellow 5mm LED with LED cathode to ground. Red or yellow LEDs provide a good bias voltage for the oscillator tube. Other colors are not so good. I like to mount the LED in a bezel and mount on the front panel to provide a nice blinky indicator.

You mean to connect the ground side of the 6V6 220K grid leak to the middle wiper of the int pot? And what’s the benefit/drawbacks to run the grid of the OTP compared with the cathode of V1B? Trying to learn them trem circuits