Category: Electronics
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Playing With an Aqara Smart LED Bulb
ESPhome on an Aqara Tunable white bulb? The problem I have used for some years an Aqara tunable white LED bulb for some years in the office, then bedroom at home: during the day light was kept colder with a script to adapt the colour temperature to the hour of the day, and during the…
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FIAT Panda: caricacellulare USB
Preparazione di un frontalino con caricacellulare USB Tutti gli altri articoli sulla Panda sono disponibili qui. La Panda non ha la presa accendisigari, quindi per poter caricare il cellulare e per poterlo usare durante la guida come navigatore serviva una alimentazione USB. Ho comprato due circuiti pronti in grado di abbassare la tensione fino a 5…
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Current Consumption of the Kobo Libra H2O
Measurement of the current consumption in different modes I bought a Kobo Libra H2O, which works very well, but I found no clear information about the balance between power off and standby modes. Kobo presets the device with 15 minutes auto-standby and 60 minutes auto power-off, but which is the actual consumption and when should…
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ESPhome-Controlled Power Strip
Integration with Home Assistant using a ESP8266 and ESPhome I needed a power strip which can be turned on and off remotely to power the active speakers of my AV receiver. Since I wanted some sockets always powered (for example, the AV receiver) and some switchable (the speakers), I decided to prepare a custom power…
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Check of Calibration of Cheap Temperature Humidity Sensors
Comparison of readings from common Chinese sensors with a reliable reference Chinese sensors for temperature and humidity like the one in the photo are very common and found also inside other devices, since they are extremely cheap and quite compact. They are even available with large digit temperature, or viceversa with large digits humidity. I…
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Output Impedance of Nexus 5X
Estimation of output impedance of the final audio stage In general, audio headphones should have an impedance of at least 6-8 times the output impedance of the final stage of the audio amplifier used to power them. Since my Nexus 5X is known to have a limited output power (up to 0.286 Vac) and my KNS-8400 have an input impedance of…
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Measurements of DC-DC Converters
Oscilloscope tests to check shape, ripple, accuracy Update: for some more detailed tests, check this article. I bought some DC-DC converters to make a custom car USB-charger for my phone, able to supply more than 1.5 A on each USB port, with a good filtering of the spikes from the ignition coils and with low noise.…
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Oscilloscope With an Audio Card
Description of a circuit able to feed signals into an audio card and to use it as oscilloscope Audio cards are like oscilloscopes, more or less, but they are not provided with special controls and are limited to a narrow band of frequencies, usually 20 Hz to 20 kHz or at most 45 kHz. A…
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The Etching of a Printed Circuit Board
Versione italiana in fondo Steps followed to etch at home with chloric acid and oxygen peroxide circuit board for electronic circuits Project based on Tom Gootee‘s instructions The circuit I am etching is a microphone preamp, based on the scheme available on Elliott Sound Products. To etch this board I used hydrochloric acid (32% concentration), hydrogen peroxide…