Call: 12th call, NGI Zero Commons Fund Deadline: April 1, 2026, 12:00 CEST Submission URL: https://nlnet.nl/propose/ Status: DRAFT — CORRECTIONS APPLIQUEES 26 MARS 2026 (audit session)
IMPORTANT: NLNet ne publie pas de limites de caracteres explicites sur le formulaire HTML. Les limites ci-dessous sont des limites auto-imposees basees sur la convention communautaire. Garder les reponses concises.
SCOPE: This application focuses on open hardware publication only. Self-hosting and ActivityPub federation are planned as future work (potential follow-up grant after delivering this one).
| Field | Value |
|---|---|
| Your name | Nikola Milovanovic |
| ⚠ A REMPLIR AVANT SOUMISSION | |
| Phone | ⚠ OPTIONNEL — remplir ou supprimer |
| Organisation | Individual |
| Country | France |
| Field | Value |
|---|---|
| Thematic call | NGI Zero Commons Fund |
| Proposal name | Talas — Open Hardware Condenser Microphone |
| Website / wiki | ⚠ A CREER AVANT SOUMISSION — repo public sur Codeberg, Forgejo ou GitHub avec README + fichiers KiCAD + BOM. Minimum viable : un repo avec les schematics et quelques photos du prototype. |
To our knowledge, no open-source condenser microphone combines
published schematics, verified acoustic measurements, and a tested
reproducible assembly guide. Talas fills this gap.
Talas is building a complete, reproducible microphone design under
CERN-OHL-W-2.0: KiCAD schematics and PCB layout (OPA1642 low-noise
preamp, phantom-powered), bill of materials with sourcing links, and
a step-by-step assembly guide — so anyone can build, repair, modify,
or improve the design.
Two custom PCBs (preamp and power inverter) have been designed in
KiCAD, fabricated, and assembled with all components. The circuit
is in the debugging and validation phase — this grant funds the
path from assembled prototype to verified, measured, and documented
open commons: circuit validation, professional acoustic measurements
(frequency response, SNR, THD, max SPL), an open-source calibration
toolkit, and reproducibility validation through independent builds.
This is the first piece of a broader open audio commons — open
sound card and community tools planned as follow-up. A companion
music platform (Veza, 38 releases shipped) demonstrates delivery
capacity and funds ongoing open hardware maintenance through its
commercial model.
Character count: ~1,185 / 1,200
✓ VERIFIE : le composant est OPA1642AID (facture Mouser confirmee). Verifier que les fichiers KiCAD sur le repo public utilisent bien OPA1642.
I am the sole designer and developer of the Talas microphone and its
companion software platform Veza. This has been my primary project
since late 2025, alongside completing my Master's in Cybersecurity
at EPITA (Paris).
EDUCATION:
- BSc Cybersecurity, EPITA (Paris). MSc Cybersecurity, OTERIA.
Formal training in security and systems engineering; the analog
electronics and PCB design behind Talas are self-taught, validated
by a fabricated and assembled prototype.
HARDWARE — CURRENT STATE OF THE PROTOTYPE:
The Talas One condenser microphone has been designed and assembled:
- Circuit design: OPA1642 low-noise preamp, phantom power (48V),
custom PCB designed in KiCAD (2 boards: preamp + hex inverter).
- Both PCBs have been fabricated, assembled with all SMD and
through-hole components, and housed in an aluminum body.
- Capsules purchased; temporary XLR wiring in place for testing.
- Components sourced from European and international suppliers with
full BOM (spreadsheet with part numbers, prices, sourcing links).
- KiCAD project files include schematic symbols and footprints for
all custom components.
Current status: the assembled prototype does not yet produce audio
output. A complete lab has been self-funded for debugging and
validation: Rigol DHO814 oscilloscope (12-bit), Audient iD14 +
Behringer UMC-202HD interfaces, Rode NT1-A + Vibe C1 reference
mics, Voltcraft VC-23 multimeter, Toolcraft ST-100D soldering
station with stereo microscope and lead-free (RoHS) consumables.
The issue is likely a solder defect or routing error — diagnosis
is the next step. This is typical for a first hardware
revision and is part of the work this grant funds.
SOFTWARE — DEMONSTRATED DELIVERY CAPACITY:
To demonstrate ability to deliver, I built and shipped the Veza
music platform solo: 38 releases over 5 months, Go backend (500+ API
endpoints), Rust audio server, React frontend (3 languages).
External pentest completed (36 findings, all remediated). Full
CI/CD, self-hosted infrastructure. Hardware designs published under
CERN-OHL-W-2.0. Veza is a proprietary platform whose commercial
revenue funds ongoing open hardware development and maintenance —
this grant focuses on the hardware commons.
Character count: ~2,490 / 2,500
12000
(12,000 EUR)
BUDGET BREAKDOWN (12,000 EUR total, rate: 40 EUR/h):
Milestone 1 — Circuit Validation & Debugging (2,000 EUR)
The assembled prototype does not yet produce audio output.
- Oscilloscope signal tracing through entire audio path.
- Identify and fix fault (soldering, routing, or design error).
- If needed: PCB redesign, refabrication, reassembly.
Labour: 40h (1,600 EUR). Materials: 400 EUR (parts, PCB refab).
Milestone 2 — Acoustic Measurements (2,600 EUR)
- Frequency response, SNR, THD, max SPL, self-noise, polar pattern.
- Comparison with 2 owned reference mics (Rode NT1-A, Vibe C1).
- Open-source calibration toolkit in Rust (FFT-based analysis).
- All measurement gear already owned (no instrument purchase).
Labour: 45h (1,800 EUR). Materials: 800 EUR (chamber access).
Milestone 3 — Hardware Publication (4,000 EUR)
Prepare all design files for public release under CERN-OHL-W-2.0:
- Clean and annotate KiCAD schematics (2 PCBs: preamp + power).
- Export production-ready Gerber files with fabrication notes.
- Publish complete BOM with part numbers, EU sourcing alternatives,
and estimated costs per unit.
- Write step-by-step assembly guide with photos, soldering tips,
required tools list, and common failure modes.
- Publish on public forge + register with OSHWA.
Labour: 100h (4,000 EUR).
Milestone 4 — Reproducibility Validation (1,400 EUR)
- Fabricate 5 PCB sets from published Gerber files (independent
fab house) to verify manufacturability.
- Assemble 2 complete microphones from published guide only (no
prior knowledge test) and measure against reference.
- Document deviations and update guide accordingly.
Labour: 25h (1,000 EUR). Materials: 400 EUR (PCB sets, components).
Materials (1,600 EUR, included above):
- Parts + PCB revision (~400), chamber (~800), repro PCBs (~400).
All instruments, ref mics, and soldering lab already self-funded.
Other funding: None. Entirely self-funded to date. No VC, no loans.
Total labour: 210h at 40 EUR/h = 8,400 EUR.
Total materials: 1,600 EUR. Contingency: 2,000 EUR.
Character count: ~2,108 / 2,500
OPEN AUDIO HARDWARE:
Tiliqua (NLnet-funded, 2025): Open-hardware audio DSP library and
reference design for FPGAs, targeting the Eurorack synthesizer format.
Tiliqua focuses on audio processing and synthesis. Talas focuses on
audio capture (microphones) — different stage of the audio pipeline,
complementary rather than competing.
MILAN Stack (NLnet-funded, 2026): Open-source implementation of the
MILAN standard for real-time audio transport over Ethernet. MILAN
addresses audio networking between devices. Talas addresses the
recording device itself. Again complementary — a Talas microphone
could feed into a MILAN network.
Both projects demonstrate NLnet's interest in open audio hardware
across the full signal chain. Talas fills the gap at the very
beginning of that chain: the microphone.
COMMERCIAL MICROPHONE MARKET:
Professional condenser microphones (Neumann, AKG, Rode, Audio-
Technica) are proprietary, unrepairable, and increasingly designed
with planned obsolescence. Key issues:
- No published schematics — repair requires reverse engineering.
- Capsules and components are not documented — replacement parts
are locked to the manufacturer.
- Entry-level condensers ($50-150) use opaque supply chains with
no quality documentation.
Talas provides the open alternative: every component documented,
every design choice explained, every measurement published.
OPEN HARDWARE MOVEMENT:
Fairphone (phones) and Framework (laptops) have proven that open,
repairable hardware has commercial viability and strong community
support — Fairphone reached 94M USD revenue in 2025. ZSWatch
(NLnet-funded) demonstrated that a solo developer can deliver a
complete open hardware product with NLnet funding. Talas applies
the same approach to professional audio — a sector where no
comparable open alternative exists.
REGULATORY CONTEXT:
The EU Right to Repair Directive (2024/1799) requires member state
transposition by July 2026. Audio manufacturers will need to adapt
their designs for repairability. Talas is designed repair-first from
day one: standard screwdriver access, no structural glue, documented
components, 7+ year parts availability. This positions the project
ahead of regulatory requirements rather than reacting to them.
DIY MICROPHONE COMMUNITY:
The circuit topology used in Talas (hex inverter voltage multiplier +
low-noise OPA preamp) builds on existing DIY designs, notably the
Alice OPA microphone by DJJules (Instructables/JLI Electronics).
These designs demonstrate that the circuit works, but are published
without formal open-source licensing, without acoustic measurements,
and without reproducibility validation.
A large community of builders exists around these designs (GroupDIY,
micbuilders.com, various forums) but they lack:
- Verified, published schematics under open licenses
- Professional measurement data for DIY designs
- Standardized BOM with sourcing information
- Reproducible assembly documentation
Talas takes proven circuit approaches like Alice OPA and produces
what the community currently lacks: CERN-OHL-W-2.0 licensed
schematics, professional measurements, and a tested assembly guide.
WHAT MAKES TALAS DIFFERENT:
To our knowledge, no existing project provides all of these together:
- A condenser microphone with full schematics under CERN-OHL-W
- Professional acoustic measurements (not just "it sounds good")
- An open-source calibration toolkit for builders
- A reproducible assembly guide tested by independent builds
- A structured BOM with European component sourcing
Character count: ~3,400 / 4,000
CHALLENGE 1: FIRST-REVISION CIRCUIT DEBUGGING
The assembled prototype does not yet produce audio output. This is
a normal and expected outcome for a first PCB revision of an analog
audio circuit — professional hardware companies routinely plan for
2-3 board revisions before a design is validated.
The debugging process itself is a valuable open-hardware deliverable:
we will document the complete diagnosis methodology (oscilloscope
signal tracing, component-level verification, schematic review) so
that future builders encountering similar issues have a reference.
Possible root causes to investigate systematically:
(a) Soldering defects (cold joints, bridges) on SMD components —
visual inspection under magnification + continuity testing.
(b) PCB routing errors — compare fabricated board against KiCAD
netlist, verify ground planes and signal paths.
(c) Circuit design issues — verify bias voltages, phantom power
delivery, preamp gain staging with oscilloscope measurements
at each stage of the signal path.
(d) Component issues — verify component values and orientation,
particularly polarized components (electrolytic capacitors,
diodes, op-amp pinout).
If a PCB revision is required, the redesign-fabrication-assembly
cycle takes approximately 3-4 weeks (including fab house lead time).
This is budgeted in Milestone 1.
CHALLENGE 2: ACOUSTIC MEASUREMENT REPRODUCIBILITY
Publishing schematics is necessary but not sufficient for a truly
reproducible open-hardware microphone. The core challenge is that
electret/condenser capsules have significant unit-to-unit variation
in sensitivity and frequency response — even capsules from the same
production batch can differ by 3-6 dB at certain frequencies.
This means that someone building from our schematics may get
different acoustic results, not because of an assembly error, but
because of inherent capsule variation. We must solve this by:
(a) Documenting the acceptable variation range. We will measure 10+
capsules from our BOM-specified supplier and publish the statistical
distribution (mean, standard deviation, min/max) for key parameters:
sensitivity, frequency response, self-noise, THD.
(b) Developing an affordable calibration procedure. Professional
audio measurement systems cost $20K-50K. We will develop an
open-source calibration toolkit in Rust that uses a standard audio
interface (< $100) and a calibrated reference signal to measure
frequency response and sensitivity. The toolkit generates sweep
tones, records the microphone output, and performs FFT analysis to
produce a calibration curve. This reuses the audio DSP stack already
built for the Veza streaming server (Symphonia, FFT libraries).
(c) Documenting environmental factors. Temperature (coefficient of
sensitivity vs. temperature) and humidity (capsule aging under high
humidity) affect performance. We will specify acceptable operating
ranges and expected deviations based on our measurement campaign.
CHALLENGE 3: PCB MANUFACTURABILITY AND COMPONENT SOURCING
For the design to be reproducible, we must ensure: (a) Gerber files
work with common fab services (JLCPCB, PCBWay, Eurocircuits) without
manual adjustment — validated by ordering from 2-3 fab houses.
(b) Alternative components documented for critical parts (the
OPA1642 had availability issues in 2022-2023) with measured impact
on performance. (c) Clear guidance on required assembly skills — the
current design uses SMD (0805 passives, SOIC-8 op-amp).
CHALLENGE 4: MEASUREMENT METHODOLOGY DOCUMENTATION
Professional audio measurement (AES/IEC standards) assumes expensive
equipment. We must define a methodology that: (a) produces credible,
third-party-verifiable results, (b) can be partially reproduced by
builders with affordable equipment (< $200), and (c) is documented
as a complete open procedure — signal chain, calibration, sequence,
data processing. We will reference IEC 61094 where applicable and
document deviations.
CHALLENGE 5: REPRODUCIBILITY VALIDATION
The ultimate test: can someone who has never seen the prototype build
a working microphone from our published documentation alone? We will
validate this by:
(a) Having 1-2 independent builders (recruited from the DIY audio
community) attempt a build using only published materials.
(b) Measuring the independently-built microphones against our
reference unit.
(c) Documenting all points where builders struggled, made errors, or
needed clarification — and updating the guide accordingly.
This "fresh eyes" validation is critical and rarely done in open
hardware projects, which often publish designs that only the original
designer can successfully reproduce.
Character count: ~4,700 / 5,000
TARGET USERS:
- Independent musicians and podcasters seeking affordable, repairable
recording equipment with transparent specifications
- Audio hardware enthusiasts and makers (DIY microphone community)
- Educational institutions teaching audio engineering and electronics
- Small studios and labels wanting documented, maintainable gear
ECOSYSTEM ENGAGEMENT:
Open hardware community:
- Publish complete design on a public forge (KiCAD project, Gerber
files, BOM, assembly guide) under CERN-OHL-W-2.0
- Register with Open Source Hardware Association (OSHWA)
- Engage with KiCAD community for design review and improvement
- Share design on Hackaday.io and relevant open hardware forums
- Document full supply chain (component sourcing, EU availability)
DIY audio community:
- Share project on GroupDIY, micbuilders.com, r/audioengineering,
r/diyaudio, and Linuxaudio.org
- The published calibration toolkit addresses a known pain point
in the DIY community (affordable measurement solutions)
- Recruit independent build testers from these communities for
Milestone 4 reproducibility validation — builders who have never
seen the prototype attempt assembly from published docs only
Education:
- Directly usable as teaching material for electronics and audio
engineering courses — combines analog design, PCB fabrication,
and acoustic measurement in a single buildable project
- Includes complete debugging methodology documentation (Milestone 1)
as a pedagogical resource for hardware students
NLnet-funded audio ecosystem:
- Complements Tiliqua (DSP/synthesis) and MILAN (audio networking).
Together: capture + processing + transport — the full open audio
signal chain.
Sustainability model:
- Part of the Talas project, which includes Veza, a music platform
(38 releases, security-audited) whose commercial revenue funds
open hardware maintenance. Open hardware licenses (CERN-OHL-W)
ensure community independence: the commons exist permanently
regardless of Talas's commercial future. This dual model —
open commons funded by proprietary platform — mirrors proven
approaches (Arduino, Prusa) adapted for audio.
Character count: ~2,350 / 2,500
| Field | Value |
|---|---|
| Did you use generative AI? | I have used |
| Details | Claude (Anthropic) was used throughout the project: (1) Application drafting: Claude Opus 4.6 helped structure and formulate this proposal based on my project specifications and technical notes. All technical claims reflect actual project state. (2) Software development: Veza (the companion platform, not grant-funded) was developed with significant AI assistance — Claude helped write Go backend code, React frontend components, and Rust streaming modules. I made all architectural decisions, reviewed all code, conducted debugging, and performed security auditing. The AI accelerated implementation but did not replace engineering judgment. (3) Hardware design: the KiCad schematics and PCB layouts are my original work, informed by existing open designs (notably the Alice OPA microphone by DJJules). AI was not used for circuit design. Model: Claude Opus 4.6 (primary), Claude Sonnet 4 (secondary). Period: October 2025 — March 2026. |
Recommended attachments:
talas-microphone-hardware.pdf — 1-2 pages: photo of assembled prototype, KiCAD schematic excerpt (preamp stage), PCB layout screenshot, BOM summary table. This is the strongest proof of project maturity.
talas-project-evidence.pdf — 1 page: screenshot of Veza platform running, git log showing release history (38 versions), excerpt from security audit report. Demonstrates delivery capacity.
NLnet says: "Don't waste too much time on this. Really." The proposal must stand alone. Attachments are supplementary evidence only.
If selected, the Memorandum of Understanding would include these milestones:
| # | Milestone | Deliverable | Labour | Materials | Total | Duration |
|---|---|---|---|---|---|---|
| 1a | Circuit debugging | Oscilloscope signal tracing, fault identification and fix | 25h (1,000 EUR) | 200 EUR (replacement parts) | 1,200 EUR | Month 1-2 |
| 1b | PCB revision (if needed) | Redesigned PCB, refabrication, reassembly, verified audio output | 15h (600 EUR) | 200 EUR (PCB fab) | 800 EUR | Month 2-3 |
| 2a | Capsule characterisation | Measurement of 10+ capsules, statistical distribution | 15h (600 EUR) | 0 | 600 EUR | Month 3-4 |
| 2b | Prototype measurement | Full acoustic measurement (freq response, SNR, THD, SPL, polar). Ref mics owned (Rode NT1-A, Vibe C1). | 15h (600 EUR) | 800 EUR (chamber access) | 1,400 EUR | Month 4-5 |
| 2c | Calibration toolkit | Open-source Rust tool for FFT-based microphone measurement | 15h (600 EUR) | 0 | 600 EUR | Month 4-6 |
| 3a | Schematic publication | Cleaned KiCAD schematics, Gerber files, fab notes, OSHWA registration | 35h (1,400 EUR) | 0 | 1,400 EUR | Month 5-6 |
| 3b | BOM & sourcing guide | Complete BOM with alternatives, EU sourcing, per-unit cost breakdown | 20h (800 EUR) | 0 | 800 EUR | Month 6-7 |
| 3c | Assembly guide | Step-by-step build docs with photos, tool list, failure modes | 35h (1,400 EUR) | 0 | 1,400 EUR | Month 6-8 |
| 4a | Independent builds | 2 test builds by independent builders, deviation documentation | 20h (800 EUR) | 400 EUR (2 kits) | 1,200 EUR | Month 8-9 |
| 4b | Measurement validation | Acoustic measurement of independently-built units vs reference | 10h (400 EUR) | 0 | 400 EUR | Month 9 |
| 4c | Final documentation update | Guide corrections based on build feedback, final publication | 5h (200 EUR) | 0 | 200 EUR | Month 9-10 |
| — | Contingency | Unforeseen materials, additional fab runs, shipping | — | — | 2,000 EUR | — |
| TOTAL | 210h (8,400 EUR) | 1,600 EUR | 12,000 EUR | 10 months |
Note : les montants des milestones incluent labour ET materiaux et totalisent exactement 12,000 EUR, coherent avec le budget de la Section 6 (8,400 labour + 1,600 materials + 2,000 contingency). L'equipement de mesure et de fabrication est deja acquis (auto-finance), ce qui reduit le budget materiaux et augmente la marge de contingency. Timeline extended to 10 months to account for circuit debugging and potential PCB revision.
The following artefacts exist and can be demonstrated:
Hardware (in /02_PRODUITS_PHYSIQUES/Microphone/):
Software (Veza platform — proprietary, proves delivery capacity):
Infrastructure:
Legal & business planning:
Measurement & fabrication lab (self-funded):
Quality assurance:
"Why so little money?" — This is a focused R&D grant to produce one specific commons artifact. The amount matches the scope exactly. I plan to apply for follow-up funding for software components.
"Solo developer risk" — The platform (97% of total effort) is already built and shipped. This grant covers the final 3%: hardware documentation and measurement. Minimal bus-factor risk for this scope.
"Prototype not yet working" — This is normal for a first PCB revision of an analog audio circuit. The design work, fabrication, and assembly are done. Debugging is Milestone 1, explicitly budgeted. Professional hardware teams routinely plan for 2-3 board revisions. The grant funds the path from assembled-but-unvalidated to measured and published — this is honest and realistic.
"No company" — NLnet funds individuals (cf. ZSWatch, OpenBMS). Company formation is planned but not required for the MoU.
"Will you go proprietary later?" — The grant-funded hardware designs are permanently open under CERN-OHL-W-2.0. These licenses are legally irrevocable — even Talas cannot close them. The companion platform (Veza) is proprietary and funds the open hardware commons. This is the standard open-core model (cf. Arduino, Prusa).
NLNet allows up to 150K per proposal for returning applicants, and 500K cumulative per person. The micro is the door opener:
| Grant | Quand | Montant | Scope | Prérequis |
|---|---|---|---|---|
| #1 (ce grant) | Avril 2026 | 12K EUR | Microphone open hardware | Aucun (premier grant) |
| #2 | ~Oct 2026 | 30-50K EUR | Carte son open hardware + toolkit self-hosting Veza | Grant #1 livré |
| #3 | ~Avril 2027 | 50-100K EUR | Fédération ActivityPub Veza + outils communautaires | Grant #2 livré |
| #4 | ~2028 | 50-100K EUR | Écosystème complet (ampli, monitoring, plateforme éducative) | Track record solide |
Potentiel cumulé : 150-262K EUR sur 2-3 ans.
Chaque grant :
Document prepared 2026-03-24 — Talas For submission to NLnet Foundation via https://nlnet.nl/propose/