New Teensy 4.1 DIY Synthesizer

Hallo friends :)

This is the control unit from Jeannie. For the button query, I use an ADC input to save output lines on the Teensy Board.

The LED Driver IC8 is controlled via the same SPI bus as the ADC chip but with a different CS line. This saves additional lines from Teensy Board.

The SPIN_1 - SPIN_4 lines on IC8 and 3 PWM lines from Teensy board are for the control of the SPIN FV-1 Effect chip.

Jeannie-Control.jpg




This is a my prototype and the arrangement of buttons, potentiometers, etc. will change a bit.

20210203-162112.jpg


Greetings. Rolf
 
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Hallo..

This function is not intended. But the key that was pressed first becomes active.

Today I got the FV-1 chips. These are 28 pin SMD chips but it's not difficult to solder. For comparison, an 8-pin IC.

20210205-143747.jpg


Greetings. Rolf
 
Hallo friends..

Here are complete Jeannie circuit diagram with FV-1 card. PWM1-4 and SPIN1-4 are Spin FV-1 control lines.

MCU unit
Jeannie102-MCU.jpg


Control unit
Jeannie102-Ctl.jpg


Fx unit
Jeannie-Spin-FV1.jpg


(subject to change):verwirrt:

Greetings Rolf
 
What about an Audio IN so you can route a signal thru the Filter + FX, just like the Shruthi. Maybe you could even Sample?
 
Hallo Daniel

That is not provided in Jeannie. We want to build this synthesizer very small and inexpensive with good sound.

But maybe in an XT version with many pots ans knops :mit den Augen rollen:

Gruß Rolf
 
Rolfdegen said:
Hallo Daniel

That is not provided in Jeannie. We want to build this synthesizer very small and inexpensive.

But maybe in an XT version with many pots ans knops :mit den Augen rollen:

Gruß Rolf
Click to expand...

Why dont you then use the internal Audio Systems Effects for "small and inexpensive"? Adding a simple circuitry for mixing audio input would allow to use it as an FV-1 FX/Filterbox additionally, which is a huge advantage. Then, sampling is just a ADC away.... You already add 10€+ of parts just for the effects, thus leaving the "small and inexpensive" world (btw, the Display also isnt "small" or "inexpensive"), so aditionally 1€ for an TL074 and associate Parts wont make it unsellable....
 
Thanks for your good ideas. There is hardly any space left on the circuit board.

It's open source and you can change it if you want :)
 
Hello friends :)


It is progressing. Corona also has something positive. You spend more time at home and on your computer.
Before I start laying out the boards, I want to know if everything works. I may be there
a bit old fashioned. But setting up an experiment on the breadboard always involves contact problems
and disturbances connected. I prefer to solder and am sure that there is at least no contact
problems are.

20210210-143444.jpg


The right board becomes the optional Fx board. The board will turn out a bit smaller and over later
a contact strip on the back is connected to the motherboard.


Greetings Rolf
 
Hello Tomas


I am using a 6N137. Pin 7 is Monitoring node and does not have to be connected.

6N137.jpg


Greetings from germany. Rolf
 
Very nice sounding Rolf. I will be getting a PJRC audio shield in a project in the coming weeks and look forward to following your path.
 
Hello again.. :D


The prototype of the Fv-1 circuit is now completely soldered and works flawlessly. Will be a little smaller later because of SMD
and relocation of the power circuit (+/- 5V) to the main board.

20210216-171836.jpg



20210217-010534.jpg




The Fx menu in the synth is almost ready. The parameter values are still missing after a program change. I still have to change that.

Greetings Rolf
 
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Hello and have a nice Sunday :)


There are a few changes in the circuit diagram. The DAC output (PT8211) on the Teensy Board has an active 32KHz LowPass filter. This reduces high-frequency interference signals at the input of the effect chip.

MCU-Jeannie.jpg


AMP-Jeannie.jpg



The OTA (IC5a / b) for the volume control of the effect signal (MIX) has now been moved to the output of the effect chip. This means that the noise floor at the synthesizer output is a little lower at low effect levels.

Fx-Jeannie.jpg


Greetings Rolf
 
Hello friends..


We have started to route the boards. I'm curious how big they will be.


Fx board
Fx.jpg


Greetings from germany. Rolf
 
Hello Rolf, fantastic work. I’m really enjoying see the progress on this.

I love how informative your display is, and how it gives the user lots of real time feedback. Do you have any advice or resources on how to achieve that? I would like to do something similar for my synth (real time visualization of synth parameters, oscilloscope, etc).

Thank you!
 
Hello Friends..


Our progress cannot be stopped. This time we really accelerate.


The Fx PCB is ready. Now we has started to route the "Jeannie" mainboard. I'm curious..


Fx board
Fx26022021.jpg


Mainboard
Jeannie-PCB.jpg



This is the first draft of the "Jeannie" mainboard. There will still be some changes such as the Teensy processor module (left).
This is moved further down so that the USB socket can be used from the outside.


Greetings Rolf
 
Hallo Chris :)

Thanks. When I'm done with the development I will upload my project to Githup. Its free.

I use the Arduino Lib for the graphics. Parameter settings are converted for a resolution of 128.

Look at here: https://electrotechnique.cc/

Greetings from germany. Rolf
 
New "Jeannie" layout..

Jeannie-MCU-3-0.jpg


The rectangle below the display is the Fx module. This is put on the underside.

Greetings. Rolf
 
der degenerator schlaegt zurueck.

awesome project, congrats on getting closer to the silver lining...
as others pointed out, especially the GUI on the screen is very appealing and impressive.
fv-1 also seems liket he best choice for fx, settled on that too for my diy synth after quite some research.

only criticism from my side right now would be that the pot/button/encoder arrangement still looks pretty random in this latest update.
 
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