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Trevor Marshall VCA/Ring modulator - Eurorack
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Trevor Marshall VCA/Ring modulator - Eurorack
whoop_john
I have started work on the ETI VCA, which I am calling the Trevor Marshall VCA/RING MOD, out of deference to the designer rather than the magazine.

Trevor worked with Kim Ryrie, founder of ETI and later the father of the Fairlight, so it's just possible it should be the Marshall/Ryrie VCA/RING MOD.

However, http://www.trevormarshall.com/eti.htm does not credit Ryrie with any circuit design involvement.

I am starting this thread to establish whether there is any interest in a PCB for this. I may also need some advice from the experts in due course.

Here is a new scan of the circuit, upon which I have placed the component values. On my PCB I am also adding an input pot for both inputs and a voltage follower buffer for each.



whoop_john
The lack of enthusiasm speaks volumes. It's a versatile little module, being both a VCA and ring modulator in one package - I thought it might garner more interest, but what do I know?

I guess you all just built the 100m module using the same chip, which is only a ring mod.
sammy123
I'm interested. I have the jacks for your design so that is a bonus too. Any plans for sharing a panel design or selling panels?
whoop_john
sammy123 wrote:
I'm interested. I have the jacks for your design so that is a bonus too. Any plans for sharing a panel design or selling panels?

The general idea is to get some interest and if there is enough, to manufacture a PCB.

Front panels are an issue, I know. What is the best way of getting them made? I have no problem with supplying accurate artwork. From what I understand, front panels are the most expensive part of any DIY module.
sammy123
I really can't say. I've never done a run of panels. I've used .fpd or .svg files that others have provided and had them made at Ponoko or Front panel Express here in the US.
Larrea
Actually I'm very interested, especially as a pair with the Maplin/Transient module; I think I said so in that thread.

I'd love to see this develop.
whoop_john
Larrea wrote:
Actually I'm very interested, especially as a pair with the Maplin/Transient module; I think I said so in that thread.
You did indeed.
KSS
You can make this fit in shallower cases by moving the 1K, 100K above the 3x12K upward into the space between the Switch and the Sig In jack. The trace then moves and becomes shorter and more direct which means the 4.7uF cap to their right can also slide upwards into that space. Everything else below now can also slide upwards.
Slide Mr. Neuman's head and character reference up and if you either rotate the Power input components and hdr 90 like many doepfer (which is what I would do) or just slide them up as well between the Mtg holes and move your module title to above or near Miscreant you can shave .250" (6mm) without sacrificing ease of assembly.

May not seem much, but in this era of shallow cases even a perception of too deep can hurt your sales prospects.

Personally I'd rather have sigin and sigout next to each other with CV above or below. With these changes all three extra wiring pads could be at the extreme left for those doing non-Euro builds. A 4 to 6 pin .100 hdr there (3 sets 2pins with GNDs) would be a nice MOTM style touch.

Be careful with your 5 hole pot footprint. The middle lug (wiper) of an alpha 16 style pot will often short to the two pads that will be next to it. If you offset the 3 inner .100 pins away from the PCB edge .100, and add a new middle pin for the .200 alpha type footprint, this is solved. Pots with .100 spacing have pins farther from their face so it all works out.
KSS
One more thing. There's no good reason not to have all the ElCaps face the same way. + down in this case. Even works with the 90 rotated power HDR and parts.
Can't hurt, is easier to support DIY and adds a pro touch.
KSS
Sorry, one more. You can swap the two upper 074 sets of pins and components. The 4148 and 12K will bridge the pot wiper and you can eliminate the trace going between the IC pads.

I didn't check any of this for agreement with the schematic. It's all based on my assumption that your layout is already electrically correct.
KSS
whoop_john wrote:
The lack of enthusiasm speaks volumes. - I thought it might garner more interest, but what do I know?

Saw a similar comment by Jorg recently.
It's Spring. Summer is coming, School is ending. Thoughts are moving outdoors. Happens every year. Add to that the pure hell MW has been to use getting logged out and you shouldn't be surprised that there's a dip in activity and response here. It's not personal. Patience is a good thing this time of year. Thank you for the Trevor Marshall link!
niicholas
I'm interested and would order a board if you make them w00t
fitzgreyve
I have these in one of my synths from the early 80's, the only thing I would have advised I see that you've already done - made RV1 a multiturn preset - I recall that they are slightly finicky at getting minimum breakthrough in VCA mode.
whoop_john
KSS wrote:
You can make this fit in shallower cases by moving the 1K, 100K above the 3x12K upward into the space between the Switch and the Sig In jack. The trace then moves and becomes shorter and more direct which means the 4.7uF cap to their right can also slide upwards into that space. Everything else below now can also slide upwards.
Slide Mr. Neuman's head and character reference up and if you either rotate the Power input components and hdr 90 like many doepfer (which is what I would do) or just slide them up as well between the Mtg holes and move your module title to above or near Miscreant you can shave .250" (6mm) without sacrificing ease of assembly.

May not seem much, but in this era of shallow cases even a perception of too deep can hurt your sales prospects.

Personally I'd rather have sigin and sigout next to each other with CV above or below. With these changes all three extra wiring pads could be at the extreme left for those doing non-Euro builds. A 4 to 6 pin .100 hdr there (3 sets 2pins with GNDs) would be a nice MOTM style touch.

Be careful with your 5 hole pot footprint. The middle lug (wiper) of an alpha 16 style pot will often short to the two pads that will be next to it. If you offset the 3 inner .100 pins away from the PCB edge .100, and add a new middle pin for the .200 alpha type footprint, this is solved. Pots with .100 spacing have pins farther from their face so it all works out.

Thank you for the constructive comments, much appreciated. I have tried to take on-board your suggestions. I have shaved 6.5mm off the height, which is now 43.5mm.

I wish I knew why my uploaded pictures always look so horrible and fuzzy - they are clear as a bell when I send them.

masterofstuff124
this interests me!

im down for a PCB/panel combo!
whoop_john
masterofstuff124 wrote:
this interests me!

im down for a PCB/panel combo!

Can somebody put me straight on the best way to produce panels please. It seems to be the big problem area - the panels end up costing more than the PCB and components.

I am trying to provide things for cheap. Why? Because I am a cheapskate. I cannot afford major investment in what are, for me, toys.

I appreciate that many of you want a Gucci job, Schaeffer etc., but I cannot order and stock this for people in advance. I am happy to provide artwork.

Cheapest method I can think of is 2mm acrylic with a brushed ali custom printed sticker, but how durable this is, I have no idea. I may try it out soon. I am also considering using laser-cut acrylic, which can then be used as a routing template for an ali panel. That still leaves the problem of how to add artwork to the front.

I wish I still had my silkscreening equipment.
masterofstuff124
pcbway.
aluminum pcb panels.
will be something like $5 a panel.

got to design the panel in PCB software but the results are very nice.
whoop_john
masterofstuff124 wrote:
pcbway.
aluminum pcb panels.
will be something like $5 a panel.

got to design the panel in PCB software but the results are very nice.

05 single-sided panels 128.5mm x 5HP are $60 - $12 each
10 single-sided panels 128.5mm x 5HP are $63 - $6.3 each
20 single-sided panels 128.5mm x 5HP are $71 - $3.55 each

This is at cost, with nothing to cover any losses or contingencies such as damage or cost of posting on to final destination.
ricko
Nice to see Dr Marshall's designs getting some love.

I have an ETI 4600 (linear CV and keyboard fatally flawed designs) and I really think you are better off using a high quality modern op-amp in the audio chain instead of the 301a (or even the tl074), which is more of a noise generator than an op-amp. Especially the mixers, the output and the output buffers of modules. So IC3 of this VCA.

I think this is generally true for any synth: you want low noise opamps on any ungated audio signal (I.e all down the path from the last VCA to the final output) so there is silence when there is no note. And also for mixers where you have multiple opamp in parallel. Internally, earlier in the signal chai , begore gating/enveloping noise is not so much a problem.

Rick
KSS
Looks nice. Good to know you found it helpful. Always an unknown how someone will take comments.
Looks like the 33uF cap near the module title resisted rotation. Measuring pots instead of just trusting memory shows that the alpha 3 pin line should be 150 mils from the board edge and the .100 spaced 3 pins behind will be 225mils from the edge. This will put the alpha 16mm style mtg face plane at the PCB edge. The usual star washer behind the panel will be enough spacer.
I miss Trevor Marshall's name and it looks it will still fit above the VCA/Ringmod label?
Standard Doepfer Pot spacing is 20mm which is close enough that 800 mils can be used. FC-UK uses 700 to fit 6 pots vertically so maybe that's why you've used 700mils. There is room to drop the 2nd pot 87 or 100mils toward the switch which will please the Doepfer crowd and maybe disappoint those with much Freq Central.
Finally, if you always add a fourth pin to trimpot/preset footprints the parts that fit is vastly expanded. 3 inline, 4th middle pin 100mils offset, for a T shape. Link the middle two pins and many more trims will work. Most trims with only 3 inline pins have those pins nearer one face than your footprint shows. Shifting them to add a 4th pin will actually put the trim closer to your silkscreen of it.

I still like the idea of 6 pins (3 GNDs for RG174 coax to the jacks) across the bottom for the MOTM DIY. But you could easily add three two pin .100 footprints to allow this mid board and gain the added advantage of room for holes to ziptie the RG174. You could put pads for OUT and VC between the jacks where their traces already exist. And only a GND pin next to the existing IN pin (Slide 100K,12K pair up another 100mils). Little things like this make your PCB more easily useful to more of the SDIY population. Since you've already done the power and mtg holes, these might be worthwhile too. A few extra holes will add nothing to the cost of a board with so few already.

You may rather put the added non-Euro format pads under the Jacks since both wouldn't normally be used at the same time and having them unused may lead to questions. Never underestimate the time support of a project will take and therefore do your best to minimize it. You're going to have questions either way. So do what makes sense for you. I'd have them in place so that they may be used in addition to the jacks.

The line you have between the 0.47uF cap and its label might better be above the + for the PWR connector. If the label is moved up towards the 8K2, the line will no longer visially separate the + from the Connector.

You asked about front panels. The bitter truth is that there is no really good answer unless you make more than a few. Even your listing of the PCB prices shows this. Some have found that PCBs as front panels work great and others have found poor print quality and scratching acceptable in a PCB but not when that PCB is a Panel. So be clear with both the PCB maker you choose and the customers if you choose this route. Ask Andrew NLC and others who seem to successfully go this way.

First, accept that front panels simply are going to be costly relative to the rest. But also accept that having a front panel available is going to make your project much more desirable. Even those buying to repanel for another format will be drawn in by a front panel layout.
At an absolute minimum, provide a drawing of a suggested panel layout with dimensions if these matter. As they do in the Eurorack version. Make a PCB panel layout and an FPD. Even if you don't actually offer the panels having these will help your sales. But do try to figure a way to offer panels if you can. It really will make a difference in your return.
Next, do everything you can to increase the number of buyers so that the price of the front panel comes into reasonable range. Consider a call to Synthcube and/or Thonk to see if going that way makes sense.
Third, accept that others might feel less inhibited by a price you feel is too high. Considering their options, this makes sense. So find out what the price needs to be and charge what makes sense so that you can do another SDIY offer if you want. SDIY is always going to be filled with vocal critics of your price, regardless of what price you list. So be fair, but don't bow to the complaints in a way that is unfair to yourself. Truth is, panel prices suck. But despite the complainers, they *are* fair. And they are also the key to your success.
whoop_john
KSS wrote:
Looks nice. Good to know you found it helpful. Always an unknown how someone will take comments.

Someone who takes the trouble to comment in detail deserves consideration. Thank you. I am no Prima Donna. It is all most useful information for me.

Some of your comments are coming from the aspect of me perhaps marketing this stuff commercially and thus needing to be as versatile as possible. My approach is low cost, Eurorack, and to disfray my own costs by selling any spare inventory that accumulates. If I factored in time to layout PCBs and get them produced, it would never be an economic exercise unless I had a view to producing 100s.

Your suggestions can be incorporated and if they appeal to the non-euro brigade, then why not do them?

KSS wrote:
Looks like the 33uF cap near the module title resisted rotation.

Indeed it did. It was a surly little bugger from the outset. Personally I didn't like its attitude at all. It'll move, given a big enough crowbar.

KSS wrote:
Measuring pots instead of just trusting memory shows that the alpha 3 pin line should be 150 mils from the board edge and the .100 spaced 3 pins behind will be 225mils from the edge. This will put the alpha 16mm style mtg face plane at the PCB edge. The usual star washer behind the panel will be enough spacer.

I'll look into this further. I ordered the 3.5mm jacks but was sent ones without the mounting thread and nut. Have ordered more. These need to be in line with the pot and switch. I may change the switch to a 90º version - toggle up and down rather than across.
KSS wrote:
I miss Trevor Marshall's name and it looks it will still fit above the VCA/Ringmod label?

It didn't fit anywhere, so I shortened it. I may try typing it in a smaller font size.

KSS wrote:
Standard Doepfer Pot spacing is 20mm which is close enough that 800 mils can be used. FC-UK uses 700 to fit 6 pots vertically so maybe that's why you've used 700mils. There is room to drop the 2nd pot 87 or 100mils toward the switch which will please the Doepfer crowd and maybe disappoint those with much Freq Central.

Here I want to be somewhat selfish, as all the modules I have been producing for my own amusement - about 8 or so, so far - have been on the 700mil pitch, for the reason you stated, that 6 will fit vertically in Eurorack. It makes more sense to me.

KSS wrote:
Finally, if you always add a fourth pin to trimpot/preset footprints the parts that fit is vastly expanded. 3 inline, 4th middle pin 100mils offset, for a T shape. Link the middle two pins and many more trims will work. Most trims with only 3 inline pins have those pins nearer one face than your footprint shows. Shifting them to add a 4th pin will actually put the trim closer to your silkscreen of it.

There I was in bed last night, pondering life, as one does, and I remembered a build I did of someone's PCB - it was a 'scope clock as you ask - and the preset pins were offset and I had to kludge it. So yes this is a good idea, although the inline presets do seem more prevalent these days.

KSS wrote:
I still like the idea of 6 pins (3 GNDs for RG174 coax to the jacks) across the bottom for the MOTM DIY. But you could easily add three two pin .100 footprints to allow this mid board and gain the added advantage of room for holes to ziptie the RG174. You could put pads for OUT and VC between the jacks where their traces already exist. And only a GND pin next to the existing IN pin (Slide 100K,12K pair up another 100mils). Little things like this make your PCB more easily useful to more of the SDIY population. Since you've already done the power and mtg holes, these might be worthwhile too. A few extra holes will add nothing to the cost of a board with so few already.

I shall have to ponder this more to understand it fully.

KSS wrote:
You may rather put the added non-Euro format pads under the Jacks since both wouldn't normally be used at the same time and having them unused may lead to questions. Never underestimate the time support of a project will take and therefore do your best to minimize it. You're going to have questions either way. So do what makes sense for you. I'd have them in place so that they may be used in addition to the jacks.

I placed the dual purpose pins as per the Bissel PCB I just made. People suggested I do it this way

KSS wrote:
The line you have between the 0.47uF cap and its label might better be above the + for the PWR connector. If the label is moved up towards the 8K2, the line will no longer visially separate the + from the Connector.

This was quite last minute. I am sure you are right, there is a better placement for the legend.

KSS wrote:
You asked about front panels. The bitter truth is that there is no really good answer unless you make more than a few. Even your listing of the PCB prices shows this. Some have found that PCBs as front panels work great and others have found poor print quality and scratching acceptable in a PCB but not when that PCB is a Panel. So be clear with both the PCB maker you choose and the customers if you choose this route. Ask Andrew NLC and others who seem to successfully go this way.

I do have someone in the UK who makes really lovely engraved panels and can do black anodised 2mm or natural anodised with black infill. The prices were too steep for my el-cheapo build, but I think the mileage of others may vary. The problem here for me was also the up-front cost of getting the person to buy in a sheet of the material in the first place. I can reactivate the dialogue I had with the person.

KSS wrote:
First, accept that front panels simply are going to be costly relative to the rest. But also accept that having a front panel available is going to make your project much more desirable. Even those buying to repanel for another format will be drawn in by a front panel layout.
At an absolute minimum, provide a drawing of a suggested panel layout with dimensions if these matter. As they do in the Eurorack version. Make a PCB panel layout and an FPD. Even if you don't actually offer the panels having these will help your sales. But do try to figure a way to offer panels if you can. It really will make a difference in your return.

Again your assumption is that I wish to make a return. I have no problem in supplying an accurate template or artwork for anything I do. I trained as an architect and earned my living for many years as a graphic designer. I can draw accurately. In fact I still do all of Kenton Electronic's artwork for their products, and also their advertising, although I am now crusty and ostensibly retired.

KSS wrote:
Next, do everything you can to increase the number of buyers so that the price of the front panel comes into reasonable range. Consider a call to Synthcube and/or Thonk to see if going that way makes sense.

At this point I maybe need to talk to Thonk, I think, about things that go thunk, to use some alliterative assonance.

KSS wrote:
Third, accept that others might feel less inhibited by a price you feel is too high. Considering their options, this makes sense. So find out what the price needs to be and charge what makes sense so that you can do another SDIY offer if you want. SDIY is always going to be filled with vocal critics of your price, regardless of what price you list. So be fair, but don't bow to the complaints in a way that is unfair to yourself. Truth is, panel prices suck. But despite the complainers, they *are* fair. And they are also the key to your success.

I do agree. I am not going for robustness myself, but many others want durability.

I got slightly burned on costs when I did a transistor tester PCB offer here on Muffs, I didn't build in any extra costs. Paypal conversion fees, increased postal charges and two losses in the mail taught me that it is necessary to build in at least some potential profit, or I lose out.

I noticed in selling the Bissel board how easily costs mount. The international shipping is just slightly more than I anticipated, but the profit I built in on the PCBs covers it. I wish the cost could have been lower, but if people are working and earning, then they probably shouldn't mind and the costs are really no more than buying a drink or two in a bar. It's all relative.
dubtoms
It's too bad my only 1496 is about to be used in Fitzgreyye's Roland-ish ring mod for Eurorack. I hope you'll sort the panel issue as I really want that envelope follower of yours ! hihi

As far as masterofstuff's suggestion of using PCBway aluminium panels goes, i haven't mentioned in the other thread that Philip who run the "Pusherman" group buys on Facebook managed to break down his "retail" price for small panels to around 2 or 3 British Pounds. I think the key here is larger numbers. He has worked on deals with a few circuit designers who promote their stuff here like Timo Rozendal and Maté Szabo where they get a cut of the profit for each boards sold through the group buy. Maybe that's a solution you are willing to consider.
dubtoms
There's also Julian aka the Beast who provides custom aluminium panels manufacturing service in the UK.

Check this thread for more info
whoop_john
dubtoms wrote:
…i haven't mentioned in the other thread that Philip who run the "Pusherman" group buys on Facebook managed to break down his "retail" price for small panels to around 2 or 3 British Pounds.

I am already part of the Pusherman group - I should pay more attention to it perhaps.

Julian's panels are £2 per HP, so for a 5 HP panel that is £10. It only includes pilot holes, all at 3.3mm. Is that what people want?
whoop_john
ricko wrote:
Nice to see Dr Marshall's designs getting some love.

I have an ETI 4600 (linear CV and keyboard fatally flawed designs)…

If you thought the 4600 keyboard was fatally flawed, the 5600S was worse, with its binary weighted semitones - great on paper, nightmare in the real world, through cumulative errors and offsets in the addition chain of op-amps.
Ayab
Confirming my interest in the project.
whoop_john
New layout. I decided to use a PCB mounting switch that goes up and down, not across as I had before. If people have the usual tag version switch it will be easy to wire onto. I've ordered some switches to check sizes.

Pins added for non-euro fellahin. The unused slots from the 3.5mm sockets could be used for cable ties.

The other holes I have on the board are 2mm (Male/Female, Female/Female 2mm standoffs are easily obtained in 1mm increments),

Ayab
Looks like the Ring Mod/Vca pcb is coming along very nicely. Looking forward to it.

I particularly enjoyed reading 'The Perception of Sound' p.30/31.

http://trevormarshall.com/synth/Synth_Oct73.pdf
whoop_john
A couple of pics of my old 4600 built back in the 1970s. Solid mahogany case with mitred corners.



diablojoy
I will definitely take a couple john thumbs up
Panels , yeah it's the bane everyone struggles with DIY wise
finally decided I am going to buy a CNC machine this year so hopefully that sorts it for me
As for PCB fab panels - I am liking some of them at least the O & C, temps utile , elements and grids panels , I received recently were all very good.

regarding the 1496 - mouser seems to only have soic14 in stock
utsource have plenty in DIP though
Ayab
Really enjoyed looking at the pictures of your 4600. A very stylish design and in really great condition. Always good to have a pin matrix for the flexibility and avoids the bowl of udon noodles issue!

Mr Marshall was certainly an innovator.
forbin
Trevor Marshall was one of my lecturers at WAIT years ago and I thought that the vcf was one of the more interesting elements of the 4600. He was heavily into switched capacitor filters at the time and made an ETI modem design using them. I have one of the envelope generators as well... he was a bit of an eccentric chap and had a gas mask at the ready if people were smoking...,
whoop_john
Some progress on this project. I received 10 MC1496 ICs from China - they don't look like pulls or blacktopped knockoffs. I have one original to test against.

The PCB is currently looking like this. What might I do with that middle strip? Sensible suggestions only please. It isn't wide enough for a row of thonkiconns. How about some tiny attenuvertor cards or something?

whoop_john
The Trevor Marshall VCA/RingMod PCB is on its way to UK from China. The strip in the middle is 2 attenuvertors, to fill up space.

Not an easy birth this one. The board was bounced because of some rogue duplicated code in the Gerbers. This is down to a bug in Osmond PCB and the use of custom-defined pad shapes. I've emailed the software author. A manual edit of the files sorted the problem out.

The person at Elecrow then said they don't allow V-grooves unless I paid extra. I must have been lucky before, as I haven't been charged in the past. They do still allow profile milling as standard, so I did slots and tabs between boards.

fitzgreyve
Put me down for two of these if you have any spares (is that actually one PCB looking at the above ?).

Will go nicely with the Transient.

Did you manage to find a solution for panels ?
Ayab
whoop_john wrote:
dubtoms wrote:
…i haven't mentioned in the other thread that Philip who run the "Pusherman" group buys on Facebook managed to break down his "retail" price for small panels to around 2 or 3 British Pounds.

I am already part of the Pusherman group - I should pay more attention to it perhaps.

Julian's panels are £2 per HP, so for a 5 HP panel that is £10. It only includes pilot holes, all at 3.3mm. Is that what people want?


Sounds good to me - am happy to do some drilling. (Do have a cheap crappy drill press which I bought impulsively but I can't find a drill to fit. Must look about for an old corded one that may fit.)
whoop_john
fitzgreyve wrote:
Put me down for two of these if you have any spares (is that actually one PCB looking at the above ?).

Will go nicely with the Transient.

Did you manage to find a solution for panels ?

The PCB I showed above in red is 2 VCA/Ring Mod boards and two attenuverter boards.

I have ordered just 5 boards, ie I get 10 of everything. The design is not yet tested.

If I sell boards then you will only get one, not the whole sheet - but I might add one attenuverter as a free gift.
Zaibach
Am I too late for the party to sign up for one pcb? Well, if you have a spare pcb I would be happy to build this...
whoop_john
Zaibach wrote:
Am I too late for the party to sign up for one pcb? Well, if you have a spare pcb I would be happy to build this...

The party has not yet started. I am currently out of the country, but hopefully the PCBs will arrive soon after my return next week.
muffdiver
definitely interested in this as well.
whoop_john
muffdiver wrote:
definitely interested in this as well.

Boards are in, but there is a wrinkle that has affected both this and the utilities boards that have also arrived.

I used a part I had made for the PJ302M:



This involved slots for the socket tags and as you can't drill an oval hole, this was designated as a routed-out shape on the mechanical layer. Fair enough, only way to do it really.

I had a request back as to whether I wanted this slot plated through to the pad either side. In a previous design, the Bissel board, someone had done this automatically - exactly what was wanted. I said yes please.

But the highly-creative person decided to also connect every top pad with the top copper layer, thus shorting out all socket pins to 0v. Cosmic.

So I am in dialogue with the PCB factory to redo them and they are asking me for more illustrations of the problem.

The VCA/Ring Mod is not so much of a problem, just four tiny cuts on the board, but I am not going to offer these for sale, as it is not my fault as I see it and it does not meet my quality standards. I can at least test the boards using what I have been sent.
dubtoms
Bummer. I was looking forward to build the utilities and Bissel boards with my brand new Hakko iron. waah
oberkorn
interest here also, 1 or 2 boards if the PCB issues are resolved
slowly coming back from 6 months SDIY hiatus...
whoop_john
The PCB manufacturer now understands my problem and has asked whether I want the boards remade or a refund. I have said remake them. I think this means they accept that the problem is theirs. Either way, boards will be remade, but we need to get to the bottom of why the issue happened, so that it doesn't do so again.

The engineer who dealt with my orders was on holiday on Friday, so they have been unable to ask him why he did what he did, but they promise a response once they have done so.
KSS
It's Generally a good idea to put a "+" and "-" in copper on the trace side of a PCB's power input. Other labels can be helpful too.
A permanent backup plan against silkscreeen failure.

Okay, it's really because we dint useta have silkscreen with our DIY bds. So anything important was put in copper labels. Not a bad habit to have.
whoop_john
KSS wrote:
It's Generally a good idea to put a "+" and "-" in copper on the trace side of a PCB's power input. Other labels can be helpful too.
A permanent backup plan against silkscreeen failure.

Okay, it's really because we dint useta have silkscreen with our DIY bds. So anything important was put in copper labels. Not a bad habit to have.


Someone will manage to plug it in backwards anyway. And if he or she can't read the "+" and "-" on the top layer silkscreen, what hope do I have that they will look at the copper on the bottom? There are diodes on the inputs. I am sure someone will figure it out once nothing works.
whoop_john
New PCBs are on their way to me

Ayab
Looking good!!
julian


This design isnt spot on yet, as i need to confirm the pot type / positions.

There's also a bit of an oddity with the incline of the text making the writing look off-center, which i need to adjust for, but its close.
audiohawk
Interested in 2 PCBs and 2 Panels when the time comes.
Thank you both for your work we're not worthy
julian
All i do i chop metal - its whoop_john's project!
(i dont think any praise should really come my way)


In other news, the attenuverter -

That has very few panel controls for even a 4hp panel - however, the panel will probably need to be 4hp to accommodate a potentiometer.


What would people like to see the rest of the panel filled with?
julian


I dont even know if this is the correct control set, but its a start.

Polarity and Offset would be knobs, In and Out jacks.


I dont know if the pcb supports offset however, so that may go.
whoop_john
julian wrote:
All i do i chop metal - its whoop_john's project!
(i dont think any praise should really come my way)


In other news, the attenuverter -

That has very few panel controls for even a 4hp panel - however, the panel will probably need to be 4hp to accommodate a potentiometer.


What would people like to see the rest of the panel filled with?

The little attenuvertor PCB was a space-filler on the PCB. I'd assumed it would be similar to Fonitronik's chicklet which Thonk sells at very reasonable cost. It would directly hang off the back of a pot, for use in people's own builds. I'd not seen it as needing a front panel per se. I am not even sure I said I was going to provide this to the public. I don't particularly want to annoy Thonk.

The offset pot is not needed - there is a preset for nulling out the zero point.
calaveras
I'm interested. My passive transformer based ringmod has not turned out to be the be-all end all that I thought it would.
julian
thread revival -

Someone has just asked me to cut a panel for this project - i had to ask them for the link, and then, when they sent it me, i realised i had a panel part laid out already.


I need to confirm with John as to the actual spacing, but, when i do that, would anyone else be interested?

Cost would be GBP 15 per unit, with cheap postage - same as normal really!
calaveras
Interested, he says full well knowing he has a stack of PCBS gathering dust and a half finished wavefolder with a spiderweb connecting the Weller, the fume extractor and the Panavise.
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