this must be the place....goin strong , yeah baby!!!

Monday, September 27, 2010

x0xb0x Etudes - pt 3

VCO (that's Voltage Controlled Oscillator, if you missed it) is now complete.
VCF (filter) is also complete.

Either a) My scope is weird or b) I don't know how to use my scope.

When I check the waveforms, first square looked a little off...not entirely symmetrical along the y-axis, nor on the x-axis (ie pulsewidth looked off). Changing the tuning seems to make the wave look better though, as if the PW changes with the tuning somewhat.

Also, if you follow the fabrication manual exactly, then they forgot to mention you need to have R46 soldered in before you test the square wave.

Then I built the filter, and while it didn't look ENTIRELY correct on my scope, I'm chalking it up to either a or b above. Turning the cutoff definitely produced a much more sine-y waveform, and all the way open showed a square/saw with lots of high freq harmonics going on.

Now the biggest bummer I had though, is I'm feeling all high now, and so I decide to move on to the Envelope section. Much to my dismay, it makes a note that out of two transistors, which had previously been referred to as the same piece, they are not the same and you need one particular one in this instance. Sure enough, I had already soldered that one into the VCO earlier, thinking they were the same piece. Literally HOURS spent trying to desolder that sumbitch and in the end I totally broke / hosed the damn component. Of course, this is one of the 'rare' vintage parts that you can't just order from mouser. Luckily, I find this pedalhacker shop on ebay and I've got two replacement 2SK30A-Y K30A in the mail to me now, at a reasonable price (read, $1, $4.20 w shipping).

So production is somewhat on hold as I wait for the missing link. I will consider doing mods now, even though I initially forgot to do them on the VCF, and then qualified it by saying it's too much a pain in the ass right now, and I'll do it later.

In other news, I feel like I can solder ANYTHING now.

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