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  • Opgelost: RC522 RFID lezer leest (sommige) kaarten niet. (Deel 1)

    Opgelost: RC522 RFID lezer leest (sommige) kaarten niet. (Deel 1)

    Ik heb recent een probleem ontdekt met de RC522 rfid kaartlezer modules die men op ebay / aliexpres en dergelijk kan kopen: ze lezen sommige kaarten niet. In deze blogpost wil ik uitleggen wat het probleem is, en hoe het opgelost kan worden, in de hoop dat mensen die hetzelfde probleem tegenkomen daar wat aan…

  • How to enable Motion Detection Interrupt on MPU6050.

    The MPU6050 data sheet has a nice “marketing” section, claiming it has a DMP unit, and a couple of useful interrupts, among them a accelerometer event interrupt. However, how to actually use these features is not documented there. And I want to use the Motion Detection Interrupt (so I can put the host MCU to…

  • Fine motor skills?

    I did not know this was possible. The hollow core motors of a Cheerson CX-10 can actually be opened, and a new wire can be soldered to the brushes when the original one broke of. This started as a challenge, me stating it was impossible to open these motors without damaging them beyond repair and…

  • Python echo

    This adds a echo to a wav file. The file also gets louder, because the result is not normalized. (sample + 0.8*Othersample v.s. sample+0.8*Othersample/1.8). This is my first real experiment with DSP.  Maybe More Later(tm). Comments are welcome. (no registration necessary / pre-moderated by me) [sourcecode language=”python” wraplines=”false” collapse=”false”] """ Echo. Usage: python_Echo InpuFile.wav OutputFile.wav…

  • Continued “data transmission whistle” experiment, more successful this time

    Okay, what’s this about? Oona Räisänen challenged her readers to construct a whistle that could transmit data using FSK. And if one reads her challenge carefully it says “whistle”. Not “pea whistle“. Now THAT simplifies things a lot! A whistle design like this can be modified by inserting a magnet and wrapping a coil around…

  • (Failed) Pea whistle experiment

    Well, not really failed, since every result is a result. I just found a way how this does not work. Two in fact. Okay, what’s this about? Oona Räisänen challenged her readers to construct a whistle that could transmit data using FSK. So, I thought about replacing the pea in a pea whistle with a…

  • ATX computer power supply current limit.

    (This post is also available in Dutch) For another project I’m tinkering with an old computer power supply. While I’m at it, why not see if I can build some crude current limiting. It does not need to regulate the current neatly, as long as it is short circuit proof. A LED on the 12V…

  • ATX voeding stroombegrenzing.

    Ik ben voor een ander project wat aan het prutsen met een oude computervoeding. Nu ik toch aan het prutsen ben, eens kijken of er een simpele stroombegrenzing te klussen valt. Het hoeft geen nette stroomregeling te zijn, als het maar kortsluitvast is. Een LED op een uitgang van een computervoeding zal normaal gesproken onmiddellijk…

  • Some short notes on the Lecroy9450 repair project

    Because there is no big news yet, some short updates. – Claude Schwarz pointed me to the Yahoo user group “Lecroy Owners group”, they have design files for a HHZ406 replacement. (Made by Dieter Frieauff). So maybe the ext. trigger input can be repaired as well. – A service manual for this ‘scope (And others)…

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