[Build Thread] MW Benjolin (not Euro!)

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elmegil
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[Build Thread] MW Benjolin (not Euro!)

Post by elmegil » Sun Oct 02, 2016 10:24 am

UPDATED 2017-10-01:

I have added the EPS file for the Knobcon Workshop case (Many thanks to Altitude909 for the box design!). This can be sent to Ponoko for fabrication, the EPS file is ready to rock. An image of this case has been added to this top post as well.

Note that the BOM has been updated to use a SUB-mini switch, not just a miniature switch. IF you have the original PCBs from the group buy last November, this will take some adjustment to make it work well. The original switch is probably a shade too tall to work well.

The additional parts you need for the case are in this BOM:



Raph's case design assumes round nuts on the jacks rather than the hex nuts I prefer and normally use, as far as I can tell it doesn't make a lot of difference, and since the top is held on with standoffs, you can omit the nuts entirely without any real ill effect.

The Workshop notes are here:

https://docs.google.com/document/d/1tj8 ... 5fGJU/edit

The last page has notes about how to assemble the case.


===============================================
This is the build thread for my PCB layout of the Benjolin, I've called it the "MW Benjolin" for MuffWiggler, though obviously it's not the only one around.

If you're looking for info on the Euro Benjolin offered by Tseng Kweiwen, please check his order thread here: https://muffwiggler.com/forum/viewtopic.php?t=165775

I will flesh this out some more, but to start with here are some key links:

Build Notes:

BOM (note there are two pages, one for the base PCB, and one for the power PCB):

NOTE: the NSD10-12D12 needs to have all those numbers/letters to get the right part. Meanwell makes other things like NSD10-12S12 which is not the same thing and won't work.

Schematic:

Mouser BOM is in the build notes.

Order Thread: https://muffwiggler.com/forum/viewtopic ... 84#2352284

Dave Brown's excellent writeup of his build of one of the prototypes: http://modularsynthesis.com/hordijk/ben ... njolin.htm


Quick note: in my previous discussion on the general Benjolin PCB thread, I had not mentioned setting up the CV ins for the two oscillators so that they can cross modulate by default. I had missed that point in several of the popular available versions. I have added it "at the last minute" as it were and it will be part of this set.

So additions over the standard original Benjolin:

- cross modulation between the two oscillators (normalled on the CV inputs, can leave them turned down or use dummy plugs to not use this)
- filter CV in normalled to O2's triangle instead of having a separate O2 control
- Additional audio input to the filter with attenuator
- "looping" of the rungler, either direct (8 bit loop) or inverting (16 bit loop)


Other FAQs:

Yes, you can power two Benjolins with a single power board if you are building a dual unit.

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Some pictures....

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Last edited by elmegil on Sun Oct 01, 2017 10:13 pm, edited 7 times in total.

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Post by sduck » Sun Oct 02, 2016 7:26 pm

I built one of these for testing and I can say that no-one should have any major problems putting this together. Unless you're a dummy like me and forget to install the transistor before testing - it'll still work, sort of, just no rungling.
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Post by mrhoudis » Sun Oct 02, 2016 7:41 pm

Thanks a lot for doing this! It looks like a nice build, I'm looking forward to it.

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Post by EarlJemmings » Mon Oct 03, 2016 9:01 pm

I think I remember it being brought up in the original thread, but would the power be enough to run a dual benjolin off one psu?

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Post by elmegil » Mon Oct 03, 2016 10:37 pm

EarlJemmings wrote:I think I remember it being brought up in the original thread, but would the power be enough to run a dual benjolin off one psu?
I don't remember it from the other thread, but that's a very good question. I believe the answer is yes, but I should verify that. Stand by....

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Post by elmegil » Tue Oct 04, 2016 1:13 am

The short answer is yes; I used one of my older supplies, so I jumpered the 10R resistor (shorting it out), because I've found that higher current draws will destabilize the DC-DC even with a 10R limiting resistor. The version of the power PCB that will ship with everyone's order will simply omit the resistor.

The supply got warm, but not so hot I couldn't touch it. Got some entertaining sounds out of it as well, but unfortunately I was only recording my interface in mono, so I think it loses some of the effect.

http://soundcloud.com/elmegil/dualling-benjolins

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Post by EarlJemmings » Tue Oct 04, 2016 6:32 am

elmegil wrote:The short answer is yes...
Excellent, thanks!
Looking forward to it :guinness:

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Post by Henfield » Wed Oct 05, 2016 7:52 am

Does anyone have any examples of this being built into a 5U MOTM or MU panel? How wide does it end up being?
For Sale/Trade: 14U 84 hp Euro case . Willing to trade towards MU Modules, Moogerfooger pedals, Minifooger pedals, and other interesting effects boxes that work well with modular, try me!

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Post by elmegil » Wed Oct 05, 2016 7:55 am

Dave Brown built one of my prototypes behind a 2U MOTM panel. Using MU I'd expect to need 2MU as well.

http://modularsynthesis.com/hordijk/ben ... njolin.htm

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Post by Henfield » Wed Oct 05, 2016 8:24 am

elmegil wrote:Dave Brown built one of my prototypes behind a 2U MOTM panel. Using MU I'd expect to need 2MU as well.

http://modularsynthesis.com/hordijk/ben ... njolin.htm
Thank you for the link! I will go to the order thread and put my order in, then figure out if I can build it myself, or get an expert to build it for me.
For Sale/Trade: 14U 84 hp Euro case . Willing to trade towards MU Modules, Moogerfooger pedals, Minifooger pedals, and other interesting effects boxes that work well with modular, try me!

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Post by elmegil » Wed Oct 05, 2016 9:16 am

BTW I should note that with Dave's feedback the latest version of the PCB has separate headers for all the signals necessary to wire to off-PCB components, so there's no need to spread headers all over the board the way he did.

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Post by CLee » Sat Oct 08, 2016 5:07 pm

Looking forward to building one of these. I have a couple of questions...

For people building these with banana jacks, how do you deal with the lack of normals? Do you figure you need to patch or do you add switches to normal the CV INS?

I'm thinking of building it as a stand-alone instrument with a CGS Reverb built in. Does it make sense to build in a mixer to feed the verb? All the outs (8) into a mono mix?

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Post by Repeater » Sat Oct 08, 2016 5:37 pm

CLee wrote:Looking forward to building one of these. I have a couple of questions...

For people building these with banana jacks, how do you deal with the lack of normals? Do you figure you need to patch or do you add switches to normal the CV INS?

I'm thinking of building it as a stand-alone instrument with a CGS Reverb built in. Does it make sense to build in a mixer to feed the verb? All the outs (8) into a mono mix?
I built mine with bananas and have no regrets.

Image

FYI: The filter output is line level, whereas the other outputs are around +/-5V. A built in mixer may be useful, but having the individual outputs available at jacks is also important for disrupting the stock Benjolin behavior (once you get sick of that) and finding all the wild stuff it can do with extra feedback paths. If I were to redo my panel I'd add a 3-to-1 mixer for each Benjolin, but I've never felt the need to use all 8 outputs at any one time.

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Post by elmegil » Sat Oct 08, 2016 5:57 pm

CLee wrote:For people building these with banana jacks, how do you deal with the lack of normals? Do you figure you need to patch or do you add switches to normal the CV INS?
You would just have to patch them in. I guess if you had a slightly wider panel/box, you could put a switch off to the side, or for example if I was doing it as a 4U panel and wanted that I'd probably just not mount the PCB to the panel and use the headers.
CLee wrote:I'm thinking of building it as a stand-alone instrument with a CGS Reverb built in. Does it make sense to build in a mixer to feed the verb? All the outs (8) into a mono mix?
Yes I think so. Note that if you're feeding other audio circuits, you may want to implement the normalization mods that Dave Brown mentions on his page. Otherwise, squares (pulse, pwm, xor to a lesser extent) are rail to rail (17Vpp), and triangles are closer to 8Vpp than 10Vpp. Also the VCF out is at line level, that will likely need to be boosted up to be comparable when mixing with the others, that's not something Dave changed.

You could also make it so the mixer feeds the VCF instead of the usual always PWM + Rungler into it. On the final version I've moved a couple resistors around to make it easy to cut the inputs from the actual input resistors (R51 & R47 for the filter and resonance respectively) to facilitate this--cut the trace between R51 & R48, that's where the inputs go to the respective sections, and then feed R48 from the mixer instead of from the external audio input. Really at that point you're best off not using my PCB controls and using the headers instead.

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Post by elmegil » Sat Oct 08, 2016 5:58 pm

@Repeater: I assume that's a dual? :)

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Post by elmegil » Sat Oct 08, 2016 6:14 pm

BTW CLee, have you heard of the Zeitgeist? It's a PT2399 based delay also designed by Rob Hordijk, I have some notes about making a stripboard version to go with my Benjolin, we'll see how it goes. Info about the Zeitgeist is at electro-music.com along with the the original press-n-peel of the Benjolin.

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Post by Repeater » Sat Oct 08, 2016 7:16 pm

elmegil - Yep, mine's a double. I just double checked the voltages on mine (built with the original PCB layout) and the VCO Pulse outputs are as close to rail-to-rail as my TL074s allow, slightly above +/-8V. Apologies for the confusion. :tu:

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Post by CLee » Sat Oct 08, 2016 8:15 pm

Thanks, I'll check out the Zeitgeist.

I'll be building from the headers probably. Maybe I'll add switches to normal the CVs. I'd like to have it at least functional without patch cords.

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Post by elmegil » Tue Nov 22, 2016 9:53 am

DHL tells me that the PCBs should be here this Friday.... I've ordered the shipping materials and they're on their way to me as well. Did some estimates of shipping costs, that all looks to meet expectations, so we're rockin' and rollin'.....

Hopefully this thread will wake up some more soon :)

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Post by elmegil » Mon Nov 28, 2016 1:47 pm

Good news: PCBs have arrived!

Image



Bad news: Power PCBs do not have mounting holes :( This is my mistake, somehow they're not on the PCB layout any longer either.


Strategies for mounting the power PCBs....

1) drill holes yourself, there is clearance, and for someone with a drill press or steady hands, it shouldn't be difficult (and I will provide extras as needed if you have a problem with this approach).

2) clips -- I have some phone cord clips, they're meant to be nailed into walls to hold flat phone cord for routing inside your home. These could be nailed to a wooden enclosure, screwed (with small enough screws) to same, or small bolts (e.g. M2 will fit through the holes in the ones I have) if mounting to metal (note that the holes do have some angle to them in some/many cases, so you'll want to take this into account)

Image
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3) If you are really loosey goosey you could hot glue it, but you'd want to be sure not to short anything if you're gluing to a metal surface (e.g. the cheap hammond box in the BOM).

Any other suggestions?

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Post by elmegil » Tue Nov 29, 2016 12:49 am

Ok, build doc is updated with the correct scans and images of the actual PCBs that will ship to people, as well as the notes about the power PCB's lack of holes.

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Post by shred » Tue Nov 29, 2016 11:23 am

any tips on printing an accurate size drill template? considering options for enclosures and i know the relative size of the PCB but I can't seem to get an exact print out of it

edit: also, mouser part# 512-1N4001 appears to no longer be available, and they suggest as a similar product 863-1N4001RLG... would this be ok to use in its place?
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Post by elmegil » Tue Nov 29, 2016 11:38 am

shred wrote:any tips on printing an accurate size drill template? considering options for enclosures and i know the relative size of the PCB but I can't seem to get an exact print out of it
It should be right on any print device capable of reproducing 300 dots per inch. ?

Note that I created the template before shrinking the PCB a tiny bit in the vertical dimension; I didn't change the controls layout so I didn't change the template to reflect that.

Spacing between pots should be 1" horizontally, and 1.5" vertically between the first three rows, and 1" vertically between the last two rows. Spacing between the jacks should be 3/4" in both dimensions except for the rungler out jack which is 1" down from the jack above it.
shred wrote:edit: also, mouser part# 512-1N4001 appears to no longer be available, and they suggest as a similar product 863-1N4001RLG... would this be ok to use in its place?

I hate parts obsolescence. Yeah, any 1N4001 should be just fine. I'll go fix the BOM/mouser part list later today.

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Post by shred » Tue Nov 29, 2016 12:01 pm

elmegil wrote:
shred wrote:any tips on printing an accurate size drill template? considering options for enclosures and i know the relative size of the PCB but I can't seem to get an exact print out of it
It should be right on any print device capable of reproducing 300 dots per inch. ?

Note that I created the template before shrinking the PCB a tiny bit in the vertical dimension; I didn't change the controls layout so I didn't change the template to reflect that.

Spacing between pots should be 1" horizontally, and 1.5" vertically between the first three rows, and 1" vertically between the last two rows. Spacing between the jacks should be 3/4" in both dimensions except for the rungler out jack which is 1" down from the jack above it.
shred wrote:edit: also, mouser part# 512-1N4001 appears to no longer be available, and they suggest as a similar product 863-1N4001RLG... would this be ok to use in its place?

I hate parts obsolescence. Yeah, any 1N4001 should be just fine. I'll go fix the BOM/mouser part list later today.
I'm sure it's my ignorance and not anything wrong with the template, I'll mess a little more with my printer settings.

Thanks for your help!
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Post by fma » Tue Nov 29, 2016 12:19 pm

Since I just bought 2 of the PCB's I now have to figure out what format they are going to take. I know a bunch of folks are doing Non-Eurorack versions. And I think I have seen a couple of standalone versions.

What else are people thinking about doing? Part of me wants to do a Euro like stand alone skiff with a matrix mixer (The NLC stuff seems well suited in a Benjolin world) and then some sort of reverb/delay.

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