New module coming: Flanger

Discussion and support for users and builders of Oakley Sound musical products.

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eljay
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Filling Vias

Post by eljay » Fri Feb 09, 2018 5:35 am

After a bit of a DIY delay I've finally started to make the Flanger module, only my second SMD project and the first was tiny in comparison. My technique is improving with practice so hopefully another excellent Oakley module will shortly be sitting proudly in my rack.

I notice from the board photos there is some inconsistency in whether you have filled a via or not. I'm assuming for an SMD board it's still good practice to fill all vias? Is it also 'good practice' to fill those vias that are under ICs prior to fitting the IC itself?

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Synthbuilder
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Re: Filling Vias

Post by Synthbuilder » Fri Feb 09, 2018 9:24 am

eljay wrote:I notice from the board photos there is some inconsistency in whether you have filled a via or not. I'm assuming for an SMD board it's still good practice to fill all vias? Is it also 'good practice' to fill those vias that are under ICs prior to fitting the IC itself?
There is no real need to fill in vias any more. Back in the day, and because I'm of that generation, plated through holes were a bit hit and miss and soldering them could help maintain connectivity when the board was flexed. These days there is no need to do this. I do still recommend doing it - if you can - since if you are water washing your board it stops the water from sneaking into the holes and possibly corroding the plating if it doesn't dry fast enough.

That said soldering via holes when the via connects to the 0V plane(s) is not easy. The large area of the copper plane will steal the heat from your soldering iron tip so any applied solder will not stay melted long enough to flow into the hole properly. The soldered part of the board surface around the via hole is not big enough to allow fast heat transfer with a iron unless you pre-heat your board. The reason some of the via holes are filled is that they do not connect to the plane but simply to other tracks. The smaller copper areas of individual tracks do not steal the heat away from the joint so readily and allow a solid fill.

So feel free to fill the unused holes but only if it results in a nice filled hole. Otherwise leave them be. If you do water wash then make sure the unsoldered holes are empty of water. Just slap the underside of the board onto a dry cloth which should dislodge any water.

Tony

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terjewinther
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Re: Filling Vias

Post by terjewinther » Sat Feb 10, 2018 2:41 am

Thanks Tony, this was a good read and good advice. Very good update on the matter.

eljay
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Test and calibration

Post by eljay » Wed Feb 14, 2018 11:23 am

Image
My Flanger, tested calibrated and completed. As can be seen from the photo a few lessons learned from my first significant SMD project. The main lesson being how not to remove an SMD IC and secondly, having removed half the solder pads and adjoining tracks, how to successfully wire a replacement chip back into the PCB.

Very much a challenge for me this module, there were a number of faults, all of them were eventually tracked down to dry solder joints on SMD chips (five in total!) so clearly my SMD soldering hadn't improved as much as I had hoped, but I learnt a lot. From tracking signal paths through the schematics to understanding a bit more about how my oscilloscope works. The best part of a day spent debugging and fixing the board but all in all a positive if frustrating at times, experience.

Now all that's left is to try it out, perhaps I'll have a rest first!

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Jim the Oldbie
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Post by Jim the Oldbie » Mon Jun 10, 2019 1:08 am

Hello all, new to this interesting forum.

Can anyone give info on the tracking of the Flanger module? I read & understand that it's not expected to track like a VCO, but the userguide mentions a useful range. Could anyone elaborate? For example, can it be made to track 1V/oct fairly well over a few octaves, something like an average VCF?

I'd like to get into pipe modeling effects & the like, and if this will work for that sort of thing, I'd be very interested in 1 or 2 of them.

Thanks for your time.

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Synthbuilder
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Post by Synthbuilder » Mon Jun 10, 2019 3:01 am

Jim the Oldbie wrote:For example, can it be made to track 1V/oct fairly well over a few octaves, something like an average VCF?
The tracking is workable over two octaves only. Very much worse than your average filter. Also it has a tendency to drift a little immediately after a CV change due to self heating of the driver transistor in the exponential convertor. This is a nice effect when the unit is used as a flanger, chorus and even a notch filter but not helpful when doing more precise analogue modelling techniques.

Tony

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Jim the Oldbie
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Post by Jim the Oldbie » Wed Jun 12, 2019 12:00 am

Thanks Tony for this info.

Meanwhile, I've discovered something in the gear closet I'd forgotten I had: A Bozak model 900 "Celeste." This was originally meant as a stereo "ambience enhancer," basically L-R + delay to the rear speakers. It uses 4 Reticon SAD1024s, and I think it's crying out to be reborn as a stereo chorus/ flanger. I think I'll see what I can do with it.

Thanks again for your reply.

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