#variometer.
Posts on the Alpisto engineering blog filed under#variometer.
- 01#flybeeper#fanet-vario#sun-vario
When does a vario beep? How a FlyBeeper vario decides, and what you can change
Between a climb tone and a sink alarm there is a band where a vario has to make up its mind, and pilots disagree about what it should do there. Some want silence the moment a thermal fades, some want to keep hearing a weak core, some want a tone almost all the time. This is how a FlyBeeper vario makes that decision, step by step: the averaging, the tone curve, two thresholds on each side, a memory of which tone is playing and an early exit on a weakening climb. Every example plays in the page, and opens in the configurator with one click.
16 min read - 02#flybeeper#fanet-vario#sun-vario
The note that never sounds: what a piezo vario actually plays
Small varios beep in a way nobody would call pleasant, and it is not because nobody cared. A piezo disc is a bell with one note of its own, and a vario plays a tune on it by feeding it square waves and letting the bell pick what it likes. I put one in a desk drawer with a microphone: at 1000 Hz the note that was asked for comes out 33 dB below its own third harmonic, loudness swings 16 dB across the tone table, and the obvious way to soften a beep turns out to make it sharper.
17 min read - 03#flybeeper#sun-vario#variometer
Fourteen metres that were never there: a soldered barometer's thermal drift
Everyone who builds these devices knows you must not solder near the barometer, and that the third rework kills it. Nobody says by how much. This one came off the bench at 470 Pa/K against a rated 0.5, inventing 14.5 metres of climb while sitting still. Thirty lines of firmware removed 95 % of that and every bench test agreed — until somebody picked the device up and the vario went the wrong way. The number behind the folklore, and why the fix helps an altimeter and provably cannot help a variometer.
24 min read - 04#flybeeper#sun-vario#variometer
Measuring a vario with a USB tester: 20 seconds per mode, and 420 µA that were never mine
I spent eight hours per data point measuring a solar variometer through its own capacitor. Then I measured the same device directly with a USB tester and got a full consumption curve in twelve minutes — along with a 420 µA floor that belonged to the cable, not the device. What both methods agree on, where they don't, and how to read a WITRN tester from Linux.
14 min read - 05#flybeeper#sun-vario#variometer
FlyBeeper SunVario: the vario you never charge
A solar audio variometer the size of a matchbox that runs off a lithium-ion capacitor instead of a battery. Thirty minutes of morning sun fills it from empty; a minute on USB-C is enough for a flying day. 29 × 34 × 12 mm, 9.8 g, one button, Bluetooth to your phone.
7 min read - 06#flybeeper#sun-vario#variometer
A 10-farad vario, measured: where every microamp goes
Eight hours of discharge logs on a solar variometer running off a 10 F lithium-ion capacitor. The current isn't constant, the buzzer isn't the main consumer, the barometer is — and the runtime formula that falls out of it. Plus what the enclosure had to become once the electronics stopped changing.
18 min read - 07#flybeeper#variometer#barometer
Why I don't put an accelerometer in my vario
A phone's barometer isn't bad — it's read badly, and that's most of why phone-only varios feel laggy. Why I poll a dedicated baro at 60 Hz instead, why an IMU costs more than it gives, how it lies to you in a spiral, and where sensor fusion actually belongs.
7 min read - 08#flybeeper#fanet-vario#fanet
See and be seen — a solar FANET vario you never have to charge
The FlyBeeper FANET Vario is a wireless, solar-powered FANET beacon and barometric variometer in one. No GPS inside — it reuses your phone's, works as a plain radio driven by the app, and puts you on the map for nearby pilots. Full app, BLE protocol and specs. A quiet pre-order at €149 with free shipping.
13 min read - 09#flybeeper#mini-bt#variometer
FlyBeeper mini BT: a Tiny Bluetooth Variometer Built on Zephyr RTOS
A dwarf-sized BLE 5 variometer on nRF52 + Zephyr RTOS, exposing pressure, temperature, altitude, four-button remote and OTA updates through standards-compliant GATT services. The entire stack — GPIO, SPI, PWM, ADC, FLASH, OTA, DFU, BLE, GATT, plus the OS — fits in 200 kB.
18 min read - 10#flybeeper#horn#variometer
FlyBeeper Horn: a Variometer-Whistle for Paraglider Pilots
The smallest variometer in the FlyBeeper line, doubling as an emergency whistle and acoustic distress beacon. A demanding miniature project that combines tight PCB design, a composite CR2032 holder, and a 3D-printed enclosure that has to actually whistle.
2 min read