Shruthi-Synthesizer and my "WAVE 1"


ok thanks will link to full site next time on my phone. these look very cool! PCBs, it’s getting real!


I’m a bit confused by the use of a 4051 and a 4052 in that schematic. why just not go for a single 4053? Seems to solve the exact same thing, but with one less component (or rather 3 since save 2 decoupling caps for powerpins :wink: )


The audio signal can be routed to Filter input or Sample input. Is the Sample input selected and you recording an Audio signal than be must switch the Filter input to mute. If not and you have seleced the monitor function on sampling page you have an feedback signal.


Memory management in DE: GENERATOR

Hi everybody. Today I will tell you something about memory management in DE:GENERATOR. As you probably already know, has the DE: GENERATOR a 1MByte large sample memory. This is connected via the EBI memory interface with the ATxmega processor. There a loaded sample file is stored, and one each waveform bank for oscillator. 1 + 2. A small memory size is for representation of the waveform on the display. The 8KByte large SRAM in Xmega processor would be much too small for the large sample files and the operating system of DE:GENERATOR approx 5KByte of SRAM for data and variables.

The first two 4K memory blocks are reserved for the bandlimited waveforms of Osc1+2. The next memory block is for one sample file. At the SRAM end are 512 user-waveforms stored for the oscillators. Each oscillator can select one user waveform ore the sample file. An administration of diffrent sample files for both oscillators is not provided at the time…

Until next time. Greeting Rolf

Die Speicherverwaltung im DE:GENERATOR
Hallöchen zusammen. Heute will ich euch etwas über Speicherverwaltung im DE:GENERATOR erzählen. Wie ihr vermutlich schon wisst, besitzt der DE:GENERATOR einen 1MByte großen Sample Speicher. Dieser ist über das EBI-Speicherinterface mit dem ATxmega Prozessor verbunden. Dort wird ein geladenes Sample-File gespeichert und jeweils eine Wellenform-Bank für Oszillator 1+2. Ein kleiner Teil des Speichers wird noch für die Darstellung der Wellenform auf dem Display benötigt. Das 8KByte große SRAM im Xmega Prozessor wäre für die großen Sample-Files viel zu klein. Außerdem benötigt das Betriebsystem des DE:GENERATOR ca. 5KByte des SRAM’s für Daten und Variablen.

Die ersten beiden 4K Speicherblöcke sind für Bandlimitierte Wellenformen von Osc1+2 reserviert. Danach folgt der Speicherblock für das Sample-File. Im hinteren Teil des Speichers werden die geladenen Wellenform-Bänke von Oszillator 1+2 gespeichert. Jeder Oszillator kann dadurch unabhängig auf eine eigene Wellenform-Bank zugreifen oder auf das geladene Sample-File. Eine Verwaltung von zwei Sample-Files für beide Oszillatoren ist zur Zeit nicht vorgesehen und hätte den Nachteil, dass sich der Speicherplatz dafür halbieren würde.

Bis zum nächsten Mal. Gruß Rolf

Pic: Sample-Ram


Hi friends… The CPU board of DE:GENERATOR is ready soldered. We have a small electronics company found that can us solder the boards. I trying yesterday mayself and takes about an hour for the complete soldering.
Now… i develop a small test adapter with an TFT display for the cpu-pcb and program some test routines.

So… geschafft. Die CPU-Platine für den DE:GENERATOR ist fertig gelötet. Wir habe eine kleine Elektronik Firma gefunden, die uns die Platinen kostengünstig löten kann. Somit entfällt das zeitaufwendige Löten der SMD-Bauteile. Ich habe es Gestern selber versucht und ca. eine Stunde für die komplette Bestücken und das Löten benötigt.
Ich baue jetzt einen kleinen Testadapter mit einem TFT-Display und programmiere ein paar Testroutinen. Dann muss das gute Teil nur noch funktionieren und ich wäre happy.



Hallo everybody…

For the DE:GENERATOR we have designe a new circuit for an 12V DC Power supply. For the negativ supply -12V we have developed a circuit with two LT1054 in parallel mode. The max output current for one LT1054 is 100mA. For the DE:GENERATOR we need 120mA. The max Output current from both LT1054 is 170mA at -10Volt. Now we have a good current reserve for extensions on the filter board.

The LM1086 is verry hot and losing much energy in heat. I think change for an LM2575 switching regulators is better idea.

Greetings Rolf


This is the final version of power supply in my synthesizer.

Now… Andre can create the motherboard pcb :slight_smile:


I have developed an little update for the delay page in my synth.

You can see on youtube


The way parameters are viewed on this synth keeps getting more and more impressive!



The day is comming… for the end :wink: This summer ::))


This is an block circuit from DE:GENERATOR

Picture Link


Hi everybody…

I want to test antother variation of the DC power supply with two switching regulator LM2596. The switching frequency is 150 kHz and the coils are smaller. Maybe I install LC filter at the switching regulator output.


Why have a 5V-LM2596 followed by a 3.3V linear regulator, when you can have 3.3V directly from a LM2596?


I guess the idea would be to clean up the voltage generated by a switched mode regulator, by using a linear one. Not sure if it’s needed for the 3.3V rail indeed, if it’s only going to power digital stuff.

Rolf, what kind of ripple do you have on the LM2596 output? I’ve tried recently to use SMPS for the digital section of my new eurorack modules. At first, I tried to roll my own thing with a TPS563200 (using TI’s webench suggested schematics/layout), and could not get less ripple than with those pre-packaged modules like the Recom R-78E3.3-0.5 / WE 173950378, which are not significantly more expensive than the switcher IC and the parts around it - and take less space on the board.


Yes I know that it will reduce ripple. But on a digital rail? Its going to power a MCU, display, buttons, etc. Those things certainly won’t have issues with a little ripple.


I need +5 Volt for the Delay chip (PT2399) and +3.3 Volt for the CPU Board.

I will test the low cost version with P3596 with ripple filter and without. Then I measure the ripple noise. The Recom R-78E3.3-0.5 makes 120Vpp rippel noise (data sheet).

Now… I want to solder the circuit :slight_smile:


Ah, I see. I should have guessed it.


I have test the lowcost P3596 L-5.0 (Reichelt 1,10 Euro). The ripple noise at 5.0 Volt Output with LC Filter (3.3uH, 220uF) is 20 mVpp (I load 200mA). The Ripple noise at 3.3 Volt Output is 5mVpp.


This is the final version of the power supply in my Synth. The ripple voltage on the output from X1 is < 30mV (I-Load 200mA). The ripple voltage on all outputs (+3.3V/200mA, +8V/100mA and -8V/100mA) is < 10mV. The switch frequency noise on +8/-8V output is -74dB.

The P3596 are verry good lowcost version of LM2596.

Pic 1: DC Power supply circuit
Pic 2: Ripple noise on Filter input L7
Pic 3: Ripple noise on Filter output L7
Pic 4: Ripple noise on +3.3V output
Pic 5: Real power supply


Hallo everybody…

I had to change power supply circuit in my synth. We had problems when turning on the synthesizer on the power grid. The voltage at the power supply has collapsed. The P3596 requires a lot of current when switched on. Now… we have build an undervoltage lockout circuit ( T1, D10) for the P3596 and is verry good. For reasons of cost and limited space on the motherboard we had used liniar regulator for +5V and +3.3V.

Pic 2:
yellow: +12V DC Power Supply
blue: negativ Voltage from P3596

Pic 3:
yellow: +12 DC Power Supply
blue: switch signal on Pin 2 on P3596