SAW / PULSE Wave Correct ?

[orange_hand]

Hi Guys,

I am just in the process of building a xoxbox and I have got a question. I have adjusted and checked the power supply on J4 on my main board. I measured 5.34 and 11,80 Volts. I have already assembled the OSC section and check the ware forms with my scope:

OSC Section:



Saw triggered with 3V:



The saw has got an amplitude of approx. 5Vpp.

Pulse triggered with 3V:



As you can see based on the scope settings the amplitude of the pulse wave is just about 1,5 Vpp which seems to be very low. Also the form looks a little bit odd.

I have checked all parts and believe that everything was correctly soldered in. Do I have already a problem or are my measurements ok ?

[SubStyler]

hi Orange,

not sure about your scope settings, but I would go on with soldering and didn't worry too much about in this early stage.

cheers,
SubStyler

btw: did you get your kit from x0xsh0p? didn't they ship the kits with SK30A-O, SK118-O and SK30A-Y?
if so, check the SK118-O for Q38 and see what happen.

[orange_hand]

did you get your kit from x0xsh0p? didn't they ship the kits with SK30A-O, SK118-O and SK30A-Y?

Yes, I did and yes, received it with those three transistors, as a part of their great service

And I replaced the SK30A-O with the SK118-O. In this case the saw wave is cleaner if you like but the pulse wave looks more or less the same. The pulse is generated from the saw, so I assume that the components for the saw are all right. The only thing I could imagine is a faulty capacitor C11, but I will leave it in there and carry on with the filter section in order to see what happens next...

I'll keep you guys posted

Cheers
orange

[orange_hand]

Hi,

I have now managed to view the pulse wave on my scope after I soldered some additional parts into the PCB. I guess if you follow exactly the instruction, then the pulse wave can't be produced properly. Attached a picture of my pulse wave



I also completed the filter section and did some tests with the filter:

A filtered pulse wave:



A filtered saw wave:



To be continued....

[antto]

the "square" waveform on the 303 (and thus on the x0x too) is NOT square at all
it can be described as a f*cked up pulse wave with frequency-dependant pulse-width and middle edge softness

all of your scope pictures look fine now, don't worry

[orange_hand]

Hi,

I am currently at the following stage with my project:









Still a long way to go ....

Cheers
orange

[antto]

cool, btw, you won't regret using sockets especially around the VCO and VCF

[orange_hand]

After yesterday's soldering job





Not yet tested....

[SubStyler]

hey Orange... nice and clean solder joints. good job so far!
don't forget to solder the legs of VR3 - VR8

[MMM]

Is it just me or are the headers J5 and J7 positioned the wrong way?

(Of course this also depends how the headers on the IOboard are soldered.)

[orange_hand]

Hi,

the headers of the connectors are oriented appropriately, of course aligned with the i/o pcb.

The encoders will be finally fixed when everything works as expected.

cheers
orange

[orange_hand]

I managed to do a first sound check of this new xoxbox after I checked the supply voltage of the various IC's in the sequencer section. Everything in the analog section works as expected !





The next decision is quite difficult, which colours will I use for the box ?



Ok, I think this looks good:



I decided to go with some nice red flat top LED's



Now I have to fit everything in this nice alloy enclosure:





And finally the control surface can be finished:









The box was tuned and works fine.

[orange_hand]

When I wanted to finish up the xoxbox I realized that the original heat sink was too big, as it was touching the transistors underneath. So I decided to come up with a custom heat sink that fits. I also drilled some holes for a better ventilation on the bottom of the case where the heat sink is located:









I also fixed the capacitors my way







The completed unit:





Now that I am done with it, I am happy that my first box is fully working straight away. Looking back I can say that it was a hell lot of work. Not sure if I want to build another one

[antto]

...but one never has "too many" 303s

[orange_hand]

That's correct. Please find attached The Acids







Cheers
orange