i’m not sure i got where that “tune all” from the megadrone circuit goes in the big picture.
is like this right?
how to apply the “tune all” if each of my oscillator (i have 4) has a circuit like this?:
do i need that mosfets? i noticed my circuit is a bit different
(in mine there is 4 oscillators with a simple mixer circuit added, working):
should mine be something like this? 
also i guess the components’ values of that “tune all” circuit should be changed based on my circuit right?? 
is there a simpler way to add a “tune all” maybe?
im super noob, so any drawing or specific components’ values would be much appreciated 
The last circuit you posted looks about right.
However, the oscillators can be globally tuned by varying the supply voltage, Ive done this and it worked.
Here is my schematic for it, note I didnt use the LED as it isn’t actually needed for the oscillators to work.
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what transistor i can use for that global tuning?
i have now at home a lot of BC558 and i have one left BC337 which i used for the 4 oscillators.
what about the value of global tunin pot and 2 resistors?
can they be just 20K for pot and 10k for the two resistors?
or i can use 10 k pot for global tunin (same aas each oscillator tune pot) ?
I used a 47k for the pot but 10k should work just as well.
You cant use a bc558 because its a PNP transistor. The bc337 should work though. The resistor between the pot wiper and the base of the transistor was 8K2 but its value is not that critical, 10k should be fine. Again for the other resistor 10K should be fine.
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i drew a stripboard layout
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The bottom end of the oscillators should go to -12v instead of Gnd, otherwise their wont be enough voltage across the transistors when the positive is lower than about +9 V
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mmh it works but the “tune all” pot stops the oscillators when is half way, towards the leg that goes to GND.
the other half it works, tuning all at the same time with not much range though since is from half way turn… should i change the values of pot or resistor then?
or should that leg of “tune all” pot go to -12v instead of ground?
(bottom of every oscillators is going to -12v after the leds , as you suggested)
Can you measure the voltage on the positive rail at different settings of the global tune pot, Im trying to get a sense of what is going wrong?
been a noob i need to be sure… with everything (electricity) ON i should measure?
should i put one pen to the positive rail and one to the GND ?
multimeter on DC voltage ?
i tryed more times… actually seems to stay at around 12,11V all the times wherever i turn the “tune all” POT, but is difficult to get any measure on my stripboard 
i tryed on the welding, or on the copper line and so on
It sounds like the pot isnt properly connected to ground at the anticlockwise end. Have you checked the voltage at the middle pin of the pot when it is being adjusted, if it outputs 0 to 12v then its fine, however if you are getting 12v out at all settings then there is either a bad connection to the pot, or the pot is damaged.
Next check the voltages on the transistor (bc337) collector should always be at12 volts, the base voltage should follow the output of the pot and the emitter should follow the voltage of the base minus about 0.65 volts. If this isnt the case check the soldering to the transistor. If there is a short on the stripboard between base and collector that could explain what is happening.
Short circuits are a common problem with stripboard and can be tricky to find sometime, it only takes a few micrometers of solder between tracks to cause trouble.
Use a bright light and a magnifying glass if you have one, to examine the stripboard.
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actually i just remembered one thing…
the pot is stereo and to use it as mono i did cut one row of legs (not only the legs actually… i cut quite a lot of the pastic that was holding the legs because i didnt want what was left to touch the stripboard … maybe i damaged the pot like that? im quite sure i did a clean job… unless the pot cannot anyway work properly with such a “treatment”
i dont have for now mono 10K…
are 100K or 500K or 500ohm ok to be used maybe? what then should be changed in case?
thank you for help, man… tomorrow ill check anyway the voltages and shorts 
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You could try 100K as the base current should be pretty low in this situation, 500K probably too big and 500 ohm would probably burn out if connected directly to 12 volts.
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it works! as you said there was a problem with the ground leg of the pot! it was connected to -12 by mistake …
i kept the 10k pot (i changed it with another stereo 10k but this time without breaking 2nd row of the legs, just keeping them disconnected)
one last thing then and im done:
to add cv to the global tune with attenuator should i do like this? with a 2M resistor? is ok with 1M (that’s what i have)? :
I think this is roughly what I used, you might need to experiment with the resistor values but 2M is way too big and the CV would have only a tiny effect on the tuning.
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@lazarusgordon Did you manage to get this working?
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yes! everythig works!
thank you so much!
i just need to change my “plastic” 3.5 socket which continue to break and some estetic choices … then ill start with a steiner/parker diode filter 
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