Erica Synths DIY opensource

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maltemark
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Re: Erica Synths DIY opensource

Post by maltemark » Sat Jul 25, 2020 1:10 pm

EATyourGUITAR wrote:
Fri Jul 10, 2020 11:08 am
I added micro swamp to my list of future projects.
Hell yeah eatyourguitar :)
Feel free to use my old samplepacks: https://freesound.org/people/altemark/
--

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Re: Erica Synths DIY opensource

Post by Dolphinwolf » Sat Aug 01, 2020 3:27 pm

EF68907C-1181-4FB0-A4A3-990D0BE80FD4.jpeg
I got this. But when I try to plug cables in they just fall out. Also the pretend knobs feel flimsy. What is wrong? :hyper:
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Re: Erica Synths DIY opensource

Post by infinitemachinery » Sat Aug 01, 2020 7:20 pm

Dolphinwolf wrote:
Wed Jul 15, 2020 12:01 pm
Looks like the sample and hold chip is hard to find but I wonder weather the TI LF398 is a substitute.
I'm going to be stocking the AS1100CK2 soon, as well as the Swamp PCBs. Might be a couple of weeks.

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Re: Erica Synths DIY opensource

Post by pjbulls » Tue Aug 11, 2020 8:40 am

KittenVillage wrote:
Fri Jul 17, 2020 5:22 pm
Any word if the MCU for the delay will have a released BOM and the firmware released?
Would be interested in knowing this as well! :party:

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Re: Erica Synths DIY opensource

Post by Dolphinwolf » Thu Aug 27, 2020 12:09 pm

infinitemachinery wrote:
Sat Aug 01, 2020 7:20 pm
Dolphinwolf wrote:
Wed Jul 15, 2020 12:01 pm
Looks like the sample and hold chip is hard to find but I wonder weather the TI LF398 is a substitute.
I'm going to be stocking the AS1100CK2 soon, as well as the Swamp PCBs. Might be a couple of weeks.
Infinitemachinery has boards and panels ready. I ordered just the pcb’s and the sample and hold chip and they look clean. The order actually came through USPS ahead of the predicted tracking schedule. Affordable, easy, now its time to populate the boards!

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Re: Erica Synths DIY opensource

Post by paperCUT » Thu Aug 27, 2020 1:57 pm

pjbulls wrote:
Tue Aug 11, 2020 8:40 am
KittenVillage wrote:
Fri Jul 17, 2020 5:22 pm
Any word if the MCU for the delay will have a released BOM and the firmware released?
Would be interested in knowing this as well! :party:
Me too, I have the PCB and panel set from Pusherman but can't do much without bom and firmware :cry:

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Re: Erica Synths DIY opensource

Post by Bamboombaps » Fri Aug 28, 2020 1:39 am

.

ThomasT
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Re: Erica Synths DIY opensource

Post by ThomasT » Thu Sep 10, 2020 12:32 pm

I could use a little help here related to packages - for some of the capacitors it is asking for CE63x25 packaging. Is this a 6.3mm diameter?

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Re: Erica Synths DIY opensource

Post by jevergreen » Tue Oct 13, 2020 12:30 pm

I'm wondering about making a couple of modifications to the build of the Erica Synths DIY Mixer II, and this would probably be the thread to ask. I'm citing the schematic from GitHub (Rev 1.0). Here's what I'm thinking about. Any thoughts would be much appreciated!

1) Putting open/closed dip switches in parallel to C1, C2, and C3 to switch between AC and DC coupling. I'm imagining soldering the caps to the opposite (front) side of the pcb and the switches to the back for easier access.
2) Inverting Out 2 by jumping off the line between R7 and R8, and adding a couple of diodes to match VD5 and VD6, instead of having two matching outputs. It looks like there is some space for these jumps on the front side, between pots.
3) If operating as a DC mixer, it would be nice to add some gain to CV signals from elsewhere in my system, which don't all go to the +/-10V expected at the DIY VCA and VCF. Or, a little distortion for audio could be cool too. I realize that with all three inputs sharing an op-amp, it would apply to the sum, but I think that's OK. This is where my circuit knowledge gets fuzzy, though. I know that adding a resistor to ground off the feedback path will make a voltage divider that will lessen the feedback and add gain, but I'm less sure when the op amp is in it's inverting configuration. Would it go between the feedback resistor and the inverting input of the op-amp, or between the output and the feedback resistor? If the feedback resistor is 100K, how would I calculate the resistor to ground value if I want a gain of 2? My apologies, I'm really new to this and really stretching my understanding.

>>Many Thanks to Erica Synths for opening up these designs on GitHub, and helping spark my desire to go deeper into how this all works!!<<
Cheers

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Re: Erica Synths DIY opensource

Post by pjbulls » Tue Oct 13, 2020 1:16 pm

For an inverting op-amp it is quite easy to calculate/change the gain. If you look at the following example from the Mixer schematic:

Image

The gain is the ratio between the feedback resistor R9 and the input resistor R8, in this case unity (ignoring the sign). If you increase the feedback resistor or decrease the input resistor you will increase the gain, for example R9=200K or R8=50K will produce a gain of -2.

The summing node at the input for the mixer works in exactly the same way. You could even have different gains for the different inputs by changing the individual input resistors (R4-R6 in the schematic), or change the gain for all inputs at once through the feedback resistor.

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Re: Erica Synths DIY opensource

Post by jevergreen » Tue Oct 13, 2020 1:41 pm

pjbulls, Thanks for the quick reply! I remembered that it was due to the ratio between input and feedback resistors, but I was making it more complicated than necessary after looking at some other schematics with non-inverting buffers, below is a clip from the Polivoks VCF schematic.
Changing the input resistors would be ideal, and yes, of course in this situation we'd be talking about inverted gain. I feel much more clear about it, much appreciated!
Gain.JPG
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Re: Erica Synths DIY opensource

Post by BROKENCODE » Sat Oct 17, 2020 9:18 am

Hello everyone, I was just approaching the mouser carts for the modules, and I can see that some of the parts are non avaiable or discontinued. Can someone help me (and maybe other people) find the correct substitutes? :mrgreen:
I'll try to put together a list. Thanks in advance!

Envelope:
missing led: https://www.mouser.it/ProductDetail/859-LTL-1CHY
is it possible to go with: https://www.mouser.it/ProductDetail/KEM ... 4eM7F_41-E
difference is the former has Vf: 2.6V, the latter 2.1V??

VCO e Bassline:
missing resistor: https://www.mouser.it/ProductDetail/603-MFR-12FTF52-10M
I couldn't find any 10MOhms 1/6W with 1% tolerance. Can I try with 1/4W?

Output:
minimum buy 4000: https://www.mouser.it/ProductDetail/647-UPM1H010MDD1TD
possible substitute??: https://www.mouser.it/ProductDetail/KEM ... 4eM7F_41-E

capacitor not avaiable: https://www.mouser.it/ProductDetail/810-FK28X7R1E474K
possibile sostituto? (classe 2): https://www.mouser.it/ProductDetail/TDK ... ZOvm1kadJQ

MIDI CV:
missing the same led as Envelope

obsolete DIN connector: https://www.mouser.it/ProductDetail/16DN100
I couldn't find any good substitute..

Modulator:
capacitor not avaiable: https://www.mouser.it/ProductDetail/810-FK28C0G1H100D
mouser suggestion: https://www.mouser.it/ProductDetail/810 ... BAnPdb_z0k

Swamp:
obsolete OP amp: https://www.mouser.it/ProductDetail/512-LM555CN
dimension could be tricky here, this seems quite compatible, but it has high level output current 200mA vs 50mA: https://www.mouser.it/ProductDetail/Tex ... HnZusud1bc
also missing the same resistor as the VCO and the Bassline

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Re: Erica Synths DIY opensource

Post by pjbulls » Sat Oct 17, 2020 11:03 am

In general, there's only few parts in a circuit that are really crucial. It may affect the initial performance a bit (and even tolerances within the same part have that effect), but that's why the controls on the panel are there as well!

To answer your specific questions, or at least try to:

the LED in the EG makes no difference at all other than visual. You may need to tweak R55 to get the brightness to your taste, but it's being buffered through a transistor straight from the positive rail so the forward voltage will make no big difference.

The 10M resistor in the Bassline provides some hysteresis for the comparator op-amp. In the VCO it's wired in series with the octave select switch, I'm not sure what the purpose is there (avoid clicks/glitches from the mechanical contacts?). In both cases the value is not critical, and it is always safe to use parts with better specs (higher wattage/voltage rating) if they fit.

The electrolytic cap in the Output is buffering an op-amp offset voltage, definitely not critical. The one you suggest should be a good replacement (and most importantly has the same physical size). I'm not sure where the ceramic 470nF one goes (I only see 47uF electrolytics in the schematic/BOM), but the ones you are linking should be interchangeable. If you meant a 47uF elco instead it is decoupling the PSU, also not very critical - mind the dimensions and voltage rating.

The MIDI socket is a bit of a challenge, I can't find any on Mouser either. However, you can find these on e-bay and many other reseller sites. Dimensions will have to fit the panel, not so much the PCB to which it is connected by wires, so you may have some flexibility here? Another option could be to use a TRS jack and connector cable instead, though apparently a few different standards exist there.

The Modulator capacitor is also fine. Since this one goes into the audio (noise) path you could stick to a class 1 dielectric (which you did, and does this matter when the output is noise?).

Finally, the 555 timer you linked has better ratings than the original so should be a fine replacement as well. Apparently the LM555 and NE555 are not completely identical under some edge cases, but that's almost certainly not going to matter here.

So, apart from the DIN connector (and maybe the 0.47uF caps) you should be good to go!

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Re: Erica Synths DIY opensource

Post by jevergreen » Sat Oct 17, 2020 12:52 pm

BROKENCODE wrote:
Sat Oct 17, 2020 9:18 am

obsolete DIN connector: https://www.mouser.it/ProductDetail/16DN100
I couldn't find any good substitute..
How about this one?
https://www.mouser.com/ProductDetail/Sw ... 8pmg%3D%3D
https://www.newark.com/switchcraft-conx ... 0connector

The data sheet I could find is horrible, but it looks like it might be a suitable replacement.

I'm looking into finding all the components for the DIY bundle myself.

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Re: Erica Synths DIY opensource

Post by infinitemachinery » Sat Oct 17, 2020 3:16 pm

jevergreen wrote:
Sat Oct 17, 2020 12:52 pm
BROKENCODE wrote:
Sat Oct 17, 2020 9:18 am

obsolete DIN connector: https://www.mouser.it/ProductDetail/16DN100
I couldn't find any good substitute..
How about this one?
https://www.mouser.com/ProductDetail/Sw ... 8pmg%3D%3D
https://www.newark.com/switchcraft-conx ... 0connector

The data sheet I could find is horrible, but it looks like it might be a suitable replacement.

I'm looking into finding all the components for the DIY bundle myself.
eBay is a good source for the DIN connector - a lot cheaper than Mouser or Newark.

Also I sell the К1100СК2 and the 140YD1201С that are used in some of the Erica Synths modules as well as panels and PCBs

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Re: Erica Synths DIY opensource

Post by diablojoy » Sat Oct 17, 2020 11:05 pm

Love your work infinitemachinery
just ordered bassline bits and pieces.
looking forward to the build .
It probably wont happen today but if it does it definitely wont go smoothly.

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Re: Erica Synths DIY opensource

Post by BROKENCODE » Sun Oct 18, 2020 5:21 am

pjbulls wrote:
Sat Oct 17, 2020 11:03 am
[long answer here]
Thank you so much, I really appreciate your explanation about each component, very helpful as well! :hail:
jevergreen wrote:
Sat Oct 17, 2020 12:52 pm
How about this one?
https://www.mouser.com/ProductDetail/Sw ... 8pmg%3D%3D
https://www.newark.com/switchcraft-conx ... 0connector

The data sheet I could find is horrible, but it looks like it might be a suitable replacement.

I'm looking into finding all the components for the DIY bundle myself.
Thanks, I somehow missed the one on Mouser! I'll add it to the list

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Re: Erica Synths DIY opensource

Post by BROKENCODE » Sun Oct 18, 2020 12:57 pm

Small updato for the missing parts. I ordered from mouser the parts for VCF, Mixer, MIDI CV and Modulator. Here's the list for what I changed. I'll give eternal gratitude if someone will have some time to check if I've done horrible mistakes (there is an high possibility percentage indeed). Sometimes, I changed the part just because they would've been avaiable next year.

Modulator
2x
original: UVR1E470MDD1TD
added: UVR1E470MDD

2x
original: UMA1C100MDD1TP
added: UMA1C100MDD

1x
original: UMA1E330MDD
added: ECE-A1EKS330

1x
original: FK28C0G1H100D
added: FG28C0G1H100DNT00

// ==============

MIDI CV
3x
original: LTL-1CHY
added: LTL-4231
this is just a LED btw


I had some second thoughts about the DIN connector that jevergreen suggested, because I wasn't able to find any data sheet with the size :hmm:

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Re: Erica Synths DIY opensource

Post by jevergreen » Sun Oct 18, 2020 3:43 pm

BROKENCODE wrote:
Sun Oct 18, 2020 12:57 pm
I had some second thoughts about the DIN connector that jevergreen suggested, because I wasn't able to find any data sheet with the size :hmm:
Yeah, the data sheet was not super helpful. I just ordered one from eBay, as suggested by pjbulls. Same price, but I was a bit more confident of the overall shape, notably the mounting holes. Fingers crossed.

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Re: Erica Synths DIY opensource

Post by pjbulls » Mon Oct 19, 2020 1:50 am

BROKENCODE wrote:
Sun Oct 18, 2020 12:57 pm
Small updato for the missing parts.
The 10 uF and 47 uF electrolytic capacitors for the Modulator originally had 2.5 mm lead spacing, your new parts are 2/1.5 mm. They are functionally OK and will fit but may sit bit wonky (though I wouldn't worry much about it).

The others look fine and I fully support replacing yellow LEDs with green ones :mrgreen:

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Re: Erica Synths DIY opensource

Post by BROKENCODE » Mon Oct 19, 2020 3:29 am

pjbulls wrote:
Mon Oct 19, 2020 1:50 am
The 10 uF and 47 uF electrolytic capacitors for the Modulator originally had 2.5 mm lead spacing, your new parts are 2/1.5 mm. They are functionally OK and will fit but may sit bit wonky (though I wouldn't worry much about it).

The others look fine and I fully support replacing yellow LEDs with green ones :mrgreen:
Thank you so much.
Yeah I thought that in the end, 0.5mm of difference would've been quite easy to fit with just tweaking the leads a little.
I can't wait to see how the green LED will shine :goo:

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Re: Erica Synths DIY opensource

Post by BROKENCODE » Mon Oct 19, 2020 4:58 am

Adding some parts changes:
BROKENCODE wrote:
Sun Oct 18, 2020 12:57 pm
Small update

Modulator
2x
original: UVR1E470MDD1TD
added: UVR1E470MDD

2x
original: UMA1C100MDD1TP
added: UMA1C100MDD

1x
original: UMA1E330MDD
added: ECE-A1EKS330

1x
original: FK28C0G1H100D
added: FG28C0G1H100DNT00

// ==============

MIDI CV
3x
original: LTL-1CHY
added: LTL-4231
this is just a LED btw
// =======================

Output
6x
original: 1C20Z5U104M050R
added: 1C20Z5U104M050B

3x
original: FK28X7R1E474K
added: FG24X7R1E474KNT00

2x
original: UPM1H010MDD1TD
added: ESC105M050AC3AA

// =======================

VCA
12x
original: 1C20Z5U104M050R
added: 1C20Z5U104M050B

// =======================

Bassline
2x
original: UVR1E470MDD1TD
added: UVR1E470MDD

1x
original: MFR-12FTF52-10M
added: MBA02040C1005FRP00

// =======================

SWAMP
2x
original: UVR1E470MDD1TD
added: UVR1E470MDD

1x
original: LM555CN
added: LM555CN/NOPB

1x
original: MFR-12FTF52-10M
added: MBA02040C1005FRP00

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