Call: 12th call, NGI Zero Commons Fund Deadline: April 1, 2026, 12:00 CEST Submission URL: https://nlnet.nl/propose/ Status: V2 — Ton personnel, budget revise (25K EUR)
SCOPE: Open hardware publication only. Self-hosting and ActivityPub federation planned as future work.
NOTE: Cette V2 remplace la V1 (12K, ton institutionnel). V1 conservee dans NGI_ZERO_COMMONS_FUND_APPLICATION.md
| Field | Value |
|---|---|
| Your name | Nikola Milovanovic |
| senke.okin@gmail.com | |
| Phone | +33 06 78 09 37 52 |
| Organisation | Individual |
| Country | France |
| Field | Value |
|---|---|
| Thematic call | NGI Zero Commons Fund |
| Proposal name | Talas — Open Hardware Condenser Microphone |
| Website / wiki | https://codeberg.org/senke/talas-one |
In early 2025 I watched a DIYPerks video and realized a
professional microphone can be built for under 50 EUR in
components. I looked for an open-source condenser microphone with
published schematics, verified measurements, and a reproducible
assembly guide. It does not seem to exist.
I am building it. Talas is a large-diaphragm condenser microphone
designed in KiCAD, based on the Alice OPA circuit topology by
DJJules (hex inverter + OPA1642 low-noise preamp), modularized
into two independent PCBs. Both boards have been fabricated and
hand-assembled. The prototype does not produce audio yet — this
is the first thing this grant funds.
This grant covers the full path from assembled prototype to
verified open commons: circuit debugging, purchasing and measuring
capsules, an open-source Rust calibration toolkit, complete
hardware publication under CERN-OHL-W-2.0, and assembly guide
validation.
I have already self-funded about 3,000 EUR in lab equipment,
components, and server infrastructure. A music platform I built
solo (Veza, 38 releases) demonstrates my ability to deliver.
Character count: ~1,135 / 1,200
I hold a Bachelor's in Cybersecurity from EPITA (Paris, graduated
September 2025) and am currently completing a Master's at OTERIA
(graduating 2027) while working part-time in cybersecurity. I
build Talas in my free time — evenings, weekends, holidays. The
analog electronics and PCB design behind this microphone are
self-taught, validated by a fabricated and assembled prototype.
THE HARDWARE — WHERE IT STANDS:
The Talas One circuit builds on the Alice OPA microphone design by
DJJules (published on Instructables, sold as kits by JLI
Electronics). I redesigned this proven topology as a modular
two-PCB architecture in KiCAD: one board for the OPA1642 preamp,
one for the hex inverter power supply. Both PCBs have been
fabricated (PCBWay), assembled with all SMD and through-hole
components, and housed in an aluminum body.
Current status: the assembled prototype does not produce audio
output. I have diagnosed this as likely a solder defect or routing
error — debugging it is Milestone 1 of this grant. I have the
complete debugging infrastructure: Rigol DHO814 oscilloscope
(12-bit), Audient iD14 + Behringer UMC-202HD audio interfaces,
Rode NT1-A and Vibe C1 reference microphones, Toolcraft ST-100D
soldering station with stereo microscope, and lead-free
consumables. All of this — roughly 3,000 EUR — was self-funded.
THE SOFTWARE — PROOF I CAN DELIVER:
I also built the Veza music platform solo: 38 releases over 5
months, Go backend (500+ API endpoints), Rust audio streaming
server, React frontend in 3 languages. I ran an AI-assisted
security audit (36 findings identified, all remediated). Full
CI/CD pipeline, self-hosted on infrastructure I built and maintain
(2x Dell R720 servers, Ansible automation, HAProxy + Coraza WAF).
Veza is proprietary and separate from this grant — I mention it
only as evidence that I ship complete projects.
I am one person doing this. That is a constraint, but also a
guarantee: every decision, every solder joint, every line of
documentation is mine to stand behind.
Character count: ~2,420 / 2,500
25000
(25,000 EUR)
I have already invested ~3,000 EUR of my own money in measurement
equipment, components, and server infrastructure. As a part-time
student, this is a significant personal commitment. This grant
funds the work, not the tools.
BUDGET (25,000 EUR total, rate: 40 EUR/h):
Milestone 1 — Circuit Debugging & PCB Revision (3,400 EUR)
Oscilloscope signal tracing through the audio path, fault
identification, fix. If needed: PCB redesign in KiCAD,
refabrication, reassembly, verified audio output.
Labour: 65h (2,600 EUR). Materials: 800 EUR (parts, PCBs).
Milestone 2 — Acoustic Measurements (3,800 EUR)
The current capsule is a t.bone SC-600 (34mm, from Thomann).
Measure it and evaluate alternatives. Full characterization:
freq response, SNR, THD, SPL, self-noise. Compare against
Rode NT1-A and Vibe C1 reference microphones.
Labour: 70h (2,800 EUR). Materials: 1,000 EUR (capsules,
chamber access).
Milestone 3 — Open-Source Calibration Toolkit (2,000 EUR)
Rust FFT-based measurement tool for affordable audio interfaces
(<100 EUR). Sweep tones, recording, calibration curves. Works
with any microphone, not just Talas. Published under AGPL v3.
Labour: 50h (2,000 EUR).
Milestone 4 — Hardware Publication (6,200 EUR)
Clean and annotate KiCAD schematics. Export production files.
Publish complete BOM with part numbers and EU sourcing. Write
step-by-step assembly guide with photos, required tools, and
documented failure modes. Register with OSHWA.
Labour: 150h (6,000 EUR). Materials: 200 EUR.
Milestone 5 — Build Validation (3,800 EUR)
Order new PCBs from the published files, assemble multiple
complete microphones using only the published guide and BOM.
Measure each against the reference unit. Document every issue.
Labour: 50h (2,000 EUR). Materials: 1,800 EUR (PCBs, parts).
Milestone 6 — Documentation Validation (2,000 EUR)
Final review: does the guide contain everything needed? Try to
recruit 1-2 DIY volunteers to attempt a build; if not possible,
self-test after a time gap. Update all docs based on feedback.
Labour: 35h (1,400 EUR). Materials: 600 EUR (component kits).
Contingency: 3,800 EUR (PCB respins, capsules, shipping).
Total: 420h labour + 4,400 EUR materials + 3,800 EUR contingency.
Timeline: 12 months from MoU (M1-2: debug, M3-5: measurements,
M5-8: publication, M9-12: validation).
No other funding. Entirely self-funded to date.
Character count: ~2,380 / 2,500
I spent months on GroupDIY and micbuilders.com looking for what I
wanted to build: a condenser microphone with published schematics,
real measurements, and a tested assembly guide. It does not exist.
WHAT EXISTS IN THE DIY COMMUNITY:
The circuit topology I use in Talas comes from the DIY community.
The Alice OPA microphone by DJJules (Instructables, JLI Electronics
kits) proved that a hex inverter voltage multiplier paired with an
OPA low-noise preamp produces studio-quality audio. I built on this
work. But DJJules' design — like most DIY microphone projects —
is published without a formal open-source license, without
professional acoustic measurements, without a BOM with sourcing
links, and without a tested, reproducible assembly guide.
This is the pattern across the entire DIY audio community: proven
circuits exist, but they live in forum posts and videos. No one has
taken the step from "it works on my bench" to "here is a formally
published, measured, and independently verified open-hardware
design that anyone can reproduce."
Talas is that step.
NLNET-FUNDED AUDIO HARDWARE:
Tiliqua (NLnet, 2025): open audio DSP for FPGAs — audio processing.
MILAN Stack (NLnet, 2026): open audio networking over Ethernet.
Both are complementary. Talas fills the first link in the open audio
chain: the microphone that captures the sound.
COMMERCIAL MICROPHONE MARKET:
Every professional condenser microphone (Neumann, AKG, Rode,
Audio-Technica) is proprietary: no published schematics, no
documented components, no repair path. When a capacitor fails,
you send it back or throw it away. Entry-level condensers (50-150
EUR) use opaque supply chains with zero quality documentation.
Talas provides what none of them do: every component documented,
every design choice explained, every measurement published.
OPEN HARDWARE MOVEMENT:
Fairphone (94M USD revenue in 2025) and Framework proved that
repairable, documented hardware has a market. ZSWatch (NLnet-
funded, solo developer) showed that one person can deliver a
complete open hardware product with NLnet support. Talas applies
this to professional audio — a sector with no comparable open
alternative.
REGULATORY CONTEXT:
The EU Right to Repair Directive (2024/1799) requires member state
transposition by July 2026. Audio manufacturers will need to adapt.
Talas is designed repair-first from day one: standard screwdriver
access, no structural glue, all components documented with
suppliers, 7+ year parts availability commitment. This positions
the project ahead of upcoming regulation.
IMPACT BEYOND TALAS:
Two deliverables from this grant are useful to the entire DIY
audio community, not just Talas builders:
- The calibration toolkit works with any microphone and any audio
interface. Anyone building a DIY mic can measure it properly.
- Capsule measurement data for affordable large-diaphragm capsules
(like the t.bone SC-600 I use) does not exist publicly. DIY
projects use these capsules with no idea of their real variation.
Publishing this data benefits every project that uses them.
WHAT MAKES TALAS DIFFERENT:
No existing project combines all of these:
- Condenser microphone with full KiCAD schematics under CERN-OHL-W
- Professional acoustic measurements (not just "it sounds good")
- Open-source calibration toolkit usable with any microphone
- Assembly guide validated through fresh rebuilds
- Structured BOM with European component sourcing
Character count: ~3,200 / 4,000
CHALLENGE 1: FIRST-REVISION DEBUGGING
When I powered on the assembled prototype for the first time, it
produced no audio output. That is where this grant starts. The
debugging process is itself a valuable open commons deliverable.
I will document the complete diagnosis: oscilloscope signal tracing
at each stage (capsule bias, preamp input, preamp output, hex
inverter rails, balanced output), component-level verification,
schematic-vs-board comparison. This methodology becomes a reference
for anyone debugging similar circuits.
Possible root causes, investigated systematically:
(a) SMD soldering defects (cold joints, bridges) — visual
inspection under stereo microscope + continuity testing.
(b) PCB routing errors — compare fabricated board against KiCAD
netlist, verify ground planes and signal integrity.
(c) Design issues — verify bias voltages, phantom power delivery,
gain staging with oscilloscope at each node.
(d) Component issues — verify values and orientation, especially
polarized components (electrolytics, diodes, op-amp pinout).
If a PCB revision is needed, the KiCAD redesign + fabrication +
assembly cycle takes 3-4 weeks. This is budgeted in Milestone 1.
CHALLENGE 2: CAPSULE VARIATION
This is the problem no one talks about publicly. Condenser capsules
have significant unit-to-unit variation — even from the same batch.
Two capsules of the same model can differ by 3-6 dB at certain
frequencies. Someone building from my schematics might get
different results not because of an assembly error, but because
of their specific capsule.
I currently use a t.bone SC-600 (34mm large-diaphragm, from
Thomann). This grant funds measuring multiple units and evaluating
alternatives, publishing the statistical distribution: mean,
standard deviation, min/max for sensitivity, frequency response,
self-noise, and THD. This gives builders realistic expectations.
No open microphone project has ever published this kind of capsule
variation data.
CHALLENGE 3: AFFORDABLE MEASUREMENT
Professional measurement systems cost 20K-50K EUR. I am developing
an open-source calibration toolkit in Rust that uses a standard
audio interface (under 100 EUR) and a calibrated reference signal
to measure frequency response and sensitivity. The tool generates
sweep tones, records the microphone output, and performs FFT
analysis to produce a calibration curve. This reuses audio DSP
libraries already proven in my Veza streaming server. Published
under AGPL v3.
CHALLENGE 4: CAN I REPRODUCE MY OWN BUILD?
Before anyone else tries, I need to prove I can do it again
myself. I will order new PCBs from the published files (same
process as my original PCBWay order), assemble multiple complete
microphones from scratch using only the published guide and BOM,
and measure each against the reference. Any variation between
units gets documented — is it the capsule, the assembly, or the
board? The BOM will include alternative components for critical
parts (the OPA1642 had availability issues in 2022-2023).
CHALLENGE 5: REPRODUCIBILITY — THE REAL TEST
The ultimate test: can someone who is not me follow the
documentation and end up with a working microphone? I will
try to find 1-2 volunteers from the DIY audio community
(GroupDIY, r/diyaudio) willing to attempt a build using only
the published guide. If I find them, they receive a component
kit and keep the mic. If I cannot find volunteers, I will do
the "fresh eyes" test myself: set the project aside for weeks,
then attempt a full build using only the published documentation,
documenting every point where my own guide is unclear.
This kind of validation is almost never done in open hardware.
Most published designs can only be reproduced by the original
designer. I want Talas to be the exception.
Character count: ~4,050 / 5,000
I learned circuit design from this community. DJJules published the
Alice OPA topology that my circuit builds on. DIYPerks showed that
professional audio quality is achievable at low cost. GroupDIY
forums taught me what I did not learn in school. This grant lets
me give back in the most useful way possible: a formally published,
measured, and verified design under an irrevocable open license.
TARGET USERS:
- Independent musicians and podcasters who want repairable,
transparent recording equipment
- DIY audio builders who want verified schematics, not forum posts
- Electronics and audio engineering students and educators
- Small studios wanting documented, maintainable gear
ENGAGEMENT PLAN:
DIY audio community (where this project comes from):
- Publish on GroupDIY, micbuilders.com, r/audioengineering,
r/diyaudio, Linuxaudio.org, and Hackaday.io
- The calibration toolkit directly addresses a pain point I
experienced: no affordable way to measure a DIY microphone
against professional standards
- Attempt to recruit 1-2 volunteers for build testing (Milestone
6) — they get a component kit and keep the mic they build
Open hardware ecosystem:
- Full design published on public forge under CERN-OHL-W-2.0
- Register with OSHWA (Open Source Hardware Association)
- Engage KiCAD community for design review and improvement
- Document complete supply chain with EU sourcing alternatives
Education:
- The project combines analog circuit design, PCB fabrication,
acoustic measurement, and embedded tooling in a single buildable
artifact — directly usable as teaching material
- The debugging methodology (Milestone 1) and capsule statistical
analysis (Milestone 2) are pedagogical resources in themselves
NLnet audio ecosystem:
- Complements Tiliqua (DSP/synthesis) and MILAN (networking).
Capture + processing + transport = the full open audio chain.
Sustainability:
- Talas includes Veza, a music platform (38 releases, security-
audited) whose commercial revenue funds ongoing open hardware
maintenance. CERN-OHL-W ensures the commons exist permanently,
regardless of the company's future. This mirrors proven models
(Arduino, Prusa) adapted for audio.
Character count: ~2,380 / 2,500
| Field | Value |
|---|---|
| Did you use generative AI? | I have used |
| Details | Claude (Anthropic, model: Claude Opus 4.6) was used to help structure, draft, and review this application based on my project documentation, hardware notes, and technical specs. All technical claims, measurements, design decisions, and project descriptions reflect actual project state. The AI assisted with English formulation and organizing my notes into the required format. Date: March 2026. |
talas-microphone-hardware.pdf — Prototype photos (assembled, disassembled, capsule close-up, PCBs, lab setup), KiCAD schematics (preamp + hex inverter), PCB layouts, BOM summary table, milestone overview.
talas-project-evidence.pdf — Veza delivery metrics (38 releases, 500+ endpoints, 661 components), security audit results (36/36 remediated), infrastructure overview, open-core licensing model.
| # | Milestone | Deliverable | Labour | Materials | Total | Duration |
|---|---|---|---|---|---|---|
| 1a | Circuit debugging | Oscilloscope signal tracing, fault identification and fix | 40h (1,600 EUR) | 400 EUR (parts) | 2,000 EUR | Month 1-2 |
| 1b | PCB revision (if needed) | Redesigned PCB, refabrication, reassembly, verified audio | 25h (1,000 EUR) | 400 EUR (PCB fab) | 1,400 EUR | Month 2-3 |
| 2a | Capsule characterisation | Measure t.bone SC-600 capsules, evaluate alternatives, publish variation data | 35h (1,400 EUR) | 600 EUR (capsules) | 2,000 EUR | Month 3-4 |
| 2b | Prototype measurement | Full acoustic measurement (freq response, SNR, THD, SPL, polar) against Rode NT1-A and Vibe C1 | 35h (1,400 EUR) | 400 EUR (chamber) | 1,800 EUR | Month 4-5 |
| 2c | Calibration toolkit | Open-source Rust FFT-based measurement tool, documented, tested, published under AGPL v3 | 50h (2,000 EUR) | 0 | 2,000 EUR | Month 4-6 |
| 3a | Schematic publication | Cleaned KiCAD schematics (2 PCBs), production files, fab notes, OSHWA registration | 45h (1,800 EUR) | 0 | 1,800 EUR | Month 5-6 |
| 3b | BOM & sourcing guide | Complete BOM with alternatives, EU sourcing, per-unit cost breakdown | 30h (1,200 EUR) | 0 | 1,200 EUR | Month 6-7 |
| 3c | Assembly guide | Step-by-step build docs with photos, tool list, failure modes, FAQ | 75h (3,000 EUR) | 200 EUR (photos) | 3,200 EUR | Month 6-8 |
| 4a | Self-rebuild test | Order new PCBs, assemble multiple mics from published guide only, measure against reference | 50h (2,000 EUR) | 1,800 EUR (PCBs, components) | 3,800 EUR | Month 8-10 |
| 5a | External validation | Recruit 1-2 DIY volunteers for build test (or self-test after time gap), document all issues | 20h (800 EUR) | 600 EUR (kits) | 1,400 EUR | Month 9-11 |
| 5b | Final doc update | Incorporate all feedback, update guide/BOM/schematics, final publication | 15h (600 EUR) | 0 | 600 EUR | Month 11-12 |
| — | Contingency | PCB respins, additional capsules, shipping, unforeseen | — | — | 3,800 EUR | — |
| TOTAL | 420h (16,800 EUR) | 4,400 EUR | 25,000 EUR | 12 months |
Note : 16,800 EUR labour (420h x 40 EUR/h) + 4,400 EUR materials + 3,800 EUR contingency (15%) = 25,000 EUR. Les heures sont coherentes avec la Section 6. Timeline : 12 mois depuis la signature du MoU.
REMPLIR l'email dans Section 1
CREER un repo public (Codeberg/Forgejo/GitHub) avec :
- README du projet (en anglais)
- Fichiers KiCAD (schematics au minimum)
- BOM (meme en l'etat actuel)
- 2-3 photos du prototype assemble
- Licence CERN-OHL-W-2.0
REMPLIR l'URL du repo dans Section 2
VERIFIER : KiCAD files reference OPA1642 (not OPA1652)
VERIFIER les PDF attachments
Verifier les character counts
SOUMETTRE AVANT LE 1ER AVRIL 2026, 12:00 CEST
| Aspect | V1 (12K) | V2 (25K) |
|---|---|---|
| Ton | "We", "the project" | "I", premiere personne |
| Montant | 12,000 EUR | 25,000 EUR |
| Capsules | "10+" (jamais fait) | Achat + mesure financees par le grant |
| Validation | 2 builds externes | Self-rebuild + 1-2 volontaires si possible |
| Toolkit calibration | Fusionne avec mesures | Milestone dedie |
| Investissement perso | Non mentionne | ~3K EUR |
| Credits DJJules | Mentionne | Central au narratif |
| CE/RoHS | Non mentionne | Hors scope (explicite) |
| Grant | Quand | Montant | Scope |
|---|---|---|---|
| #1 (ce grant) | Avril 2026 | 25K EUR | Microphone open hardware |
| #2 | ~Oct 2026 | 30-50K EUR | Carte son open hardware + toolkit self-hosting |
| #3 | ~Avril 2027 | 50-100K EUR | Federation ActivityPub + outils communautaires |
Document prepared 2026-03-31 — Talas For submission to NLnet Foundation via https://nlnet.nl/propose/