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DIY - Elektor Vocoder - New kits available now !
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3, ... 15, 16, 17  Next [all]
Author DIY - Elektor Vocoder - New kits available now !
Fitchie
Today I finished the input/output unit (RU 80068-3).

Component side (172 mm x 72 mm):



And this is the solder side:

Fitchie
KSS wrote:
I see now the original is the same orientation but only see two Vregs? At a minimum you could add some decent PCB-based heatsinking traces and pours as is seen on many power PCBs using SMD. You have the clean open areas available to do this. Done well, these PCB trace and via-based cooling techniques can make a big difference.

That's correct. The original design has only 7815 and 7915 volt regulators on the power supply, and +5 and -5 volt was made on the backplane with a 78L05 and 79L05.
The new design does include all regulators on the power supply card. And the power dissipation is so limited that the heatsinks are above the mark.
BugBrand
You definitely want to up the trace sizes on the PSU PCB.

Interesting project by the way.
& Harald's vocoder project is simply beautiful - would love to build the analysis & meter panels.
Fitchie
BugBrand wrote:
You definitely want to up the trace sizes on the PSU PCB.

Thanks for the feedback.

Current design:

- high voltage AC traces are 1 mm
- low voltage DC traces are 0,6 mm

What would you like to suggest ?
Fitchie
In the meantime the band filter (RU 80068-4) is ready too.
In totaal 8 of these PCB's are needed to build the vocoder.

Component side (172 mm x 72 mm):



And solder side:



Beside the 8 bandfilters, also a low pass and high pass filter is needed to complete the project.

Below one can see the block diagram of the filter units:

BugBrand
Fitchie wrote:
BugBrand wrote:
You definitely want to up the trace sizes on the PSU PCB.

Thanks for the feedback.

Current design:

- high voltage AC traces are 1 mm
- low voltage DC traces are 0,6 mm

What would you like to suggest ?


As big as you can go - 0V, especially, but also the DC power lines.
Fitchie
On request, here is the updated power supply (RU 80068-2):

- remarkable bigger AC traces
- considerable bigger DC traces and ground traces
- copper area under every power regulator for extra dissipation
- cover plate to avoid touching the AC part

Also the backplane has got an important update: power & ground traces are now accommodated on both sides of the PCB.

Component side power supply:



Solder side:



Cover plate:

Fitchie
Quick update: the low pass filter has just been finished (RU 80068-5).
This PCB is based on the band filter (RU 80068-4) as published a few posts earlier, only the component layout and silkscreen is slightly different.

Component side low pass filter (172 mm x 72 mm):



Solder side:



Next and latest PCB is the high pass filter (RU 80068-6). I'll try to complete this design the next week.
LED-man
Very interesting project.
Please count me in for it.
Jarno
Looks great, very clean, and sensibly compact. Maybe add some mounting holes for the PCB's? Maybe not everyone will use the DIN backplane? (A lot of Formant builds also do not have the DIN connector). And those holes right next to the DIN connector footprint, are they soldering pads or regular mounting holes?

I like the polygons in the "armpits" of tracks as well, the fills, classic look. I also notice now, all of these are single sided, right? Particular reason?
Given that the PCB's are single sided, you REALLY did a good job of routing the boards, not too many jumpers if I am not mistaken.
Fitchie
@LED-man & Jarno,

Thanks for the nice feedback !

Jarno wrote:
Maybe add some mounting holes for the PCB's? Maybe not everyone will use the DIN backplane?

The goal is (after final assembling) to draw a stiff wire on the sides to fix the PCB's by soldering them to this wire. Therefore all PCB's have small soldering holes on the corners.
Given there are no tracks around the soldering holes, you are free to drill them as big as you want. In that case just use the holes as center point.

Jarno wrote:
I also notice now, all of these are single sided, right? Particular reason? Given that the PCB's are single sided, you REALLY did a good job of routing the boards, not too many jumpers if I am not mistaken.

My intention was to preserve the nostalgia as much as possible, including the 'armpits' and the single sided design. There are some tracks on the component side of the PCB's to avoid wire bridges. Only the backplane has a multi later layout for ground and current tracks.
KSS



Moving nicely along!

Mod pics should be mostly self explaining. The red circle is near what on your board is a probable fatal error. There is not enough clearance there between the traces.

A copper pad under the heatsink will simply rise to the heat level of the Vreg tab and sit there. You do have a bit of oversize which will radiate. The mod pic shows a way to greatly increase the effectiveness of the pcb heatsink through increased area, vias as heat-conductive paths to additional radiating area on the other side of the insulating pcb. I didn't show vias under the Vreg tab, but they could be useful too. If not needed for the original, an idea shared below may make them worthwhile. They certainly don't hurt.

When you have the area to use, go ahead and use it. Spread heat sources apart from each other. The mod pic shows the upper two Vregs moved only, but the red arrows show to move the others. Diodes also moved to allow larger traces and spaces and to remove them a bit as heat sources from the heat sensitive capacitors. Towards the heat producing transformer too, as it's not likely to be a problem. I didn't do a complete redraw, only hitting enough to show the ideas for you to use or not.

The original Power PCB you posted shows few spindly tracks from the large ground area. The capacitors connect at an apex of a triangular extension to this large area. The mod pic shows a similar shape where you had thin traces. Your traces should be at least as wide as the originals. Wider won't hurt.

Lastly, do you think the single backplane is a good idea?
The original design makes more sense, and doesn't inhibit your other improvements.
You have 11 similar sized boards and one cover PCB which at about 1/3 the size will fit in their shadow. A nice compact package. But then you have this single long thin easily bent or broken in shipment backplane PCB. At 400mm or more when packaged it's no longer requiring only a simple standard padded envelope or box. Even stacking the 11-1/3 pcbs on top of it in pairs will not really change this shipping consideration. Split it as the original and all these issues disappear. The package is then a typical and much smaller size more likely to survive postal rigors. The downside is only a few more wires to solder between two halves.

One more benefit is that a split backplane PCB allows for additional filters, noise source, voiced/unvoiced detection and other upgrades and modifications in a smaller increment by fitting one or more in between or at the end of the original pair using a third backplane. Were I in your shoes, I would make another filter size board including the cover to have 12 plus the two backplanes. 14 PCBs, with one including the cover and an additional few spaces of backplane. This narrow bus has a few extra spaces and connectors for mods or upgrades. Either V-score or separate from the cover, or even drilled to snap apart it's a nice upgrade path and it evens up your shipping package. You have a solid even brick of PCBs to ship by standard box or envelope and you've given your customers an option to use or not as they see fit. And yourself as well. After all, you already have the basic vocoder! What could you do with a few more spaces in the backplane? What could your customers do with the added possibilities?

I hope you see this as constructive as I think what you're doing is a nice addition to the DIY synth world.
KSS
Not 11, 12 plus backplane. Missed out the Input/output PCB!
Fitchie
Wow great feedback !
Thanks for your extensive response !

KSS wrote:

The red circle is near what on your board is a probable fatal error. There is not enough clearance there between the traces.

Valuable suggestion: clearance has been enlarged. The order for the prototyping boards has already been placed, but the next batch will contain the suggested adjustments.

KSS wrote:

The mod pic shows a way to greatly increase the effectiveness of the pcb heatsink through increased area, vias as heat-conductive paths to additional radiating area on the other side of the insulating pcb.

Actually the power consumption is about 200 mA in total, so the 15 VDC regulators will barely dissipate 0,5 W each, the 5 VDC regulators much less. Even at hours of use, the heatsinks hardly becomes lukewarm.

KSS wrote:

The original Power PCB you posted shows few spindly tracks from the large ground area. The capacitors connect at an apex of a triangular extension to this large area. The mod pic shows a similar shape where you had thin traces. Your traces should be at least as wide as the originals.

Good one. The ground area has been reshaped and the traces have been widened to 1.2 mm.

KSS wrote:

Lastly, do you think the single backplane is a good idea?

This is a conscious choice. Putting 2 pieces together is less straightforward than it seems and makes the backplane wobbly.

KSS wrote:

But then you have this single long thin easily bent or broken in shipment backplane PCB. Even stacking the 11-1/3 pcbs on top of it in pairs will not really change this shipping consideration.

Together with the PCB's I would like to offer a 19" front in 3 mm thick anodised aluminium. That front panel is sturdy enough to support the PCB's during transport. And splitting the front panel into 2 parts would not be a good idea. :-)

KSS wrote:

One more benefit is that a split backplane PCB allows for additional filters, noise source, voiced/unvoiced detection and other upgrades and modifications in a smaller increment by fitting one or more in between or at the end of the original pair using a third backplane.

If there is enough interest, probably I want to extend the backplane with 2 extra connectors, in the condition that the backplate does not become wider than 19".

KSS wrote:

I hope you see this as constructive as I think what you're doing is a nice addition to the DIY synth world.

Absolutely, this kind of feedback is very valuable and greatly appreciated.
Fitchie
All,

What do you think about these 19" front panels?


Variant 1:

- Black anodised aluminium
- Engraved front panel, white painted infill
- Drilled and equipped with thread to allow flush mounting of the jacks & pots




Variant 2:

- Black anodised aluminium
- Color printed (UV), white underlay
- Drilled and equipped with thread to allow flush mounting of the jacks & pots




Variant 3:

- Black anodised aluminium
- Light grey printed (UV), no underlay
- Drilled and equipped with thread to allow flush mounting of the jacks & pots

PWM
Although the design looks appealing, maybe it isn't the most ergonomic option. Especially the master part where the jacks are relatively close to the pots while there is so much 'unused' space on the left side of the panel.

Great project btw! I love analog vocoders.
basicbasic
Watching with great interest SlayerBadger!
Fitchie
PWM wrote:
Especially the master part where the jacks are relatively close to the pots while there is so much 'unused' space on the left side of the panel.

Hi PWN,

Thanks for your advice.
I intended to design the front panel as symmetrical as possible. Actually there is almost no unused space left on the panel, even without brackets. Don't forget the mounting lips on the right & left side.

See picture:


But I'll try to move all knobs and plugs a little bit to the left side.
PWM
Fitchie wrote:
PWM wrote:
Especially the master part where the jacks are relatively close to the pots while there is so much 'unused' space on the left side of the panel.

Hi PWN,

Thanks for your advice.
I intended to design the front panel as symmetrical as possible. Actually there is almost no unused space left on the panel, even without brackets. Don't forget the mounting lips on the right & left side.

See picture:


But I'll try to move all knobs and plugs a little bit to the left side.


Ah yes, I did forgot those darned things..!
I think I would put the master section to the left. This has a benafit for right handed people, this seems logical to me. But this is obviously a personal preference. Either way, I do like the clean, test equipment look of the panel.
LED-man
i prefer a powerswitch for rackmount units at the frontpanel.
DPST switch, type depends on the frontpanel design

examples:
https://www.tme.eu/de/details/1832.3313/wippschalter/marquardt/
https://www.tme.eu/de/details/ae-t8550vbaaa/wippschalter/bulgin/t8550v bbb076w/
Bodo1967
Perhaps rotate the "Vocoder" logo by 90 degrees (so it is vertical) and place it on the far left, close to the edge? That'd allow the power LED (and switch wink) and everything else to move a little to the left as well.
Fitchie
Here you are ...



Boogie
not been on the forum yet,
but I would opt for VOCODER horizontally
Fitchie
My first 3D drawing experiences, but this is how it should look like...

bemerritt
I agree with the master jacks/pots. If you can somehow space it out, i think it would be nice.

Could you possibly place the In/Out jacks in two rows instead of one? Then you could tighten the whole thing up horizantily
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