For Eurorack or Kosmo one common option is a 12 V AC power brick which is then converted by a power supply board inside the case to ±12 V DC (and +5 V DC as well in the case of Eurorack); most Eurorack and Kosmo modules need both +12 V and -12 V, and some Eurorack modules need +5 V too.
For your avalanche oscillator, with suitable transistor choice, you only need +12 V, so a 12 V DC power brick would work. An AC one would not unless it goes into a power supply board to convert it to DC.
And yes, if you have a Eurorack/Kosmo power supply you could use that. You’d need a 10- or 16- pin header
which you could solder to a piece of stripboard, then make connections to the strips corresponding to ground and +12 V. Other pins on the connector would be connected to the PSU’s -12 V and +5 V but those could just be left unconnected to anything at the stripboard and they would not cause any problems.
but the question is about how actually those kind of trasnformers should be installed in a box?
Should i solder the wire straight to the legs and then lift the trasnfomer on a small platform (for the leg and cable to have space)? or should i put this trasnformer on a sort of pc board and use the board for wiring (on a standard stripboard the legs doesnt fit in the holes… i could just drill other holes or make some bigger) ??
so to connect the avalanche osc to a Eurorack/Kosmo power supply the Ground and -12V in the ribbon cable are not to be considered the same, right? i thought -12V and GRND were actually the same thing in this situation… ground and -12v
are they to be considereed the same thing only if i connect the avalanche to a DC power supply like a battery or a 12v DC block? where the negative is actually the ground?
Ground can be considered 0 volts. +12 and -12 are relative to that 0 volts. You would use +12 and ground to provide 12vdc to the circuit. With the 12v power block the 2 wires would provide 12vdc. One wire would be +12 vdc relative to th other wire.
the - (minus) of the capacitor should be connected to the + (plus) of the led, in this drawing is connected to the GND with the minus of the led…
in the other schematic he drew it correctly but not in this
also my transistor BC 337 NPN works in the opposite direction
according to a link shared by kosmo about different transistors (kerry wong website)->
the collector (in my case is the left leg facing the flat face) should goes to the + of the led.
all day, many mistakes, what a mess… , at least now is oscillating and making sound
tomorrow ill continue testing capacitors and connecting more
Next you should try connecting an ldr across the tuning pot to make a light controlled oscillator and at somepoint after that you might want to try controlling that ldr with an led. Look up vactrol.
i put
osc 1 / osc2 / osc3 / osc4
10uF / 4,7uF / 1uF / 0,47uF
can somebody help with a drawing about adding volume potentiometer for every oscillator? should i just add a pot to the output of every oscillator? no resistor, no other things?
the osc with 10uF with low tones (low frequency) is much more quiet than the other ones… i used different capacitor but maybe i chose too wide range…
why is needed another (fixed, 47K) resistance after the pot? isnt the pot already a resistance? is some kind of safety? (kosmos sometimes say something like this in the videos i think)
instead of 500K pots i could use 100K ? what resistor then to use? 10K is fine? 20 K ?
There are a few reason for the Rs.
An obvious one is if you turn two of pots to their max, you will short those two inputs one to the other (and thus, the outputs of whatever is connected to them), and that’s bad…
Another one is when you turn one of pots to its min, you will short the output to GND, and you won’t get any output from the other inputs…
If you feel confident to build the valve VCA, a “true” (active) mixer should be easy-peasy, and you won’t have to worry about all the drawbacks of a passive mixer… it’s really just a '072 and a few more resistors…
(BTW, a VCA only reduce the level… despite it’s name…)
(that valve vca should also amplify [and distort?] the signal i thought?)
mmmh yet if i build that active mixer then i need to have a separate ribbon cable to go to my psu board right? to another slot… i have only 4 slots (i can implement but i dont want now)
this simple mixer by kosmo need to have his own +12 / ground / -12 v power cable/power socket…
can i share the same i use with my 4 oscillator circuit output?
i mean connecting together +12v and ground of my 4 oscillator and +12v and ground of active mixer to the ribbon pin socket then connecting the -12 v to its pins, which i didnt use for my oscillators…
can all share the same ribbon cable, the same slot in the psu board?
other noob question:
when i bought/searched for chip like tl072, tl071, tl074… they have different ending letter… example:
kosmo write TL072 I-amp
but i found at my shop TL072CP
here you can see how many tl072 there is: Lemona
are they all good?
Operacinis stiprintuvas means op-amplifier
Yes, the active mixer would need power. You can either plug it into your power supply, wire it to your 4 oscillator circuit adding the -12V as you described, or you can build a little power bus using stripboard like this (on the right):
Though, if you do, I would recommend the box headers that @analogoutput listed above.
For the TL072 you want the TL072xP chips (PDIP/DIP8 package) for breadboard and stripboard. The different designations are for different electrical characteristics described here:
The least expensive PDIP/DIP8 package will work for most of what you want to build. You probably could get by with the TL082CP if the others remain out of stock.
thanks guys…
i actually realize that modules in general can be connected with a split ribbon cable and go to the same slot… and seeing your bus board with stripboard i also realize how simple it is to add slots, just wiring power +12v gnd -12 etc etc to another board and adding male ribbon connector…
i think i will do the active mixer then
here my project for now, many things to be fixed or rewired but im happy that it works, and didnt explode …
i saw kosmo using a “tune all” knob to move the tune of all oscillator at once. that’s quite cool but i don’t understand much of the schematic and how to apply it to my project…
in case you want to reply to this i post on the thread here
When making power cables or soldering box headers or plugging in power cables without box headers please be careful of the orientation. If there is a stripe on the cable, the convention is that it goes to -12v.
