Aliexpress’s bargains – S01E01

Ludo | 1 juillet 2017
In this episode of Aliexpress’s bargains, I’ll write a few words about what’s sold as a Nagoya UT-108UV.
I don’t delude myself, what I bought is certainly just a bad copy of a terrible clone, but whatever…
The first thing I did after opening the bubble wrap package was to unbend the nicely curved antenna, then plug it to the VNA and see how horrible it could be, and I can’t say I’ve been deceived by what I saw…

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Sirio GP430LB autopsy

Ludo | 18 juin 2017
If you ever wondered what’s inside a GP430LB or how wide is this antenna’s bandwidth, you’ve come to the right place.

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Diamond X50N to X50NA: Cut it three times and still too short!

Ludo | 18 juin 2017
This short article describes how I shortened my X50N in order to get a better reception on 446MHz.

This antenna was bought from Wimo’s website, so I’ll consider it as an genuine antenna from Diamond (not one of its numerous and probably bad clones).

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Hot cams!

Ludo | 18 juin 2017
If you know a little bit about electronics, you probably already seen TVS diodes. If not, these are Transient Voltage Suppressor diodes, placed in parallel as close as possible to the power supply input of the device, which basically sacrifice themselves by going short circuit when the applied voltage exceeds their rated breakdown voltage. Their response time is fast enough to protect the remaining electronics from damage. That’s the good part of the story.
Unfortunately, some electronic board designers don’t seem to care about what happens just after that…

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HQ POWER PS613 unleashes its power!

Ludo | 21 mai 2017
This lab PSU is also sold by Velleman, under the same product name.
I own it since almost 8 years and I never had to complain about it, aside from its voltage drift that forces to regularly adjust the voltage output.
Therefore I had no reason to doubt about it when I needed a 12V power supply for powering the IP cameras I quickly installed, before going to a 2 weeks holidays off the house.
Well… what happened next proved me wrong!

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Système de vidéosurveillance CFI-EXTEL, réf.: SVMN 87050 (IPSV 87050), avec écran intégré: que la lumière soit (éteinte)!

Ludo | 9 mai 2015

N’étant pas certain que cet appareil ait été vendu ailleurs qu’en France, du moins sous la même marque & référence, je vais vous épargner un billet en anglais approximatif 🙂

Ce système de vidéosurveillance acheté relativement cher il y a quelques années chez Castorama a quelques points faibles, notamment l’accès à distance par une interface web utilisant des ActiveX douteux nécessitant la levée de nombreuses sécurités sur Internet Explorer. De plus, il est obligatoire d’utiliser Internet Explorer 6, qui n’est plus installable sur des ordinateurs récents, ce qui nécessite l’installation d’une machine virtuelle sous Windows XP. Bien entendu, il ne faut pas compter sur un éventuel accès via votre smartphone. De toutes façons, ce n’était pas encore très répandu à l’époque à laquelle ce produit était commercialisé.
Ce problème ne sera absolument pas traité dans ce billet, puisque les sources de l’applicatif embarqué ne sont évidemment pas disponibles.
Un autre « défaut » de cet appareil pour les particuliers, c’est le fonctionnement constant du rétro éclairage de l’écran: cela consomme de l’énergie, ça émet de la lumière inutilement, et ça réduit considérablement le temps de vie du circuit d’alimentation du rétro éclairage, comparé au temps passé à surveiller ce qui est affiché. Pour une utilisation professionnelle, dans un poste de sécurité par exemple, cela ne pose pas de problème.
La modification proposée consiste à dévier le signal de commande du rétro éclairage, afin de permettre une mise en veille manuelle à l’aide d’une interrupteur.

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Unbricking Linksys WRE54G and WAP54G – When you think you can start digging their graves…

Ludo | 12 février 2015

This entry follows an older one I posted almost eight years ago here (link).
Although I tried to make it really clear, I realize that it is not the case, even to me.

I’ve been contacted recently by someone who visited that other website and who was facing the same frustrating issue with his WAP54G. The device was totally bricked, as well as his two WARE54G.
Sometimes you can strap pins, sometimes you can access the shell and enter the magic commands, and sometimes (should I say most of the time) you can just hate yourself for having done something wrong. Hopefully, such mistakes can be easily fixed as long as you have the appropriate tools.

To do so, you’ll need:

  • a soldering iron, preferably a good one like a Weller WSD50 & TCP-S (a smaller one for SMDs would even be better) with a reasonably thin conical tip. I wouldn’t recommend using a plumber soldering iron, or anything approaching;
  • tin, lead-free or not, that’s up to you;
  • desoldering braid (or the shielding of a coaxial cable if you feel like MacGyver or Bear Grylls);
  • anti-flux or flux cleaner (or alcohol but not the one you drink unless you live in Macedonia), if you want to wow your family, friends, colleagues and neighbors with shiny solderings;
  • a cutter with a breakaway blade (it can be a dull one, we won’t cut anything with it anyway);
  • an universal programmer with a TSOP48 adapter (you can find really cheap adapters on ebay or aliexpress).

The universal programmer is certainly the missing device on your workshop but you might have access to one at the university, at work or at your local electronics shop. You can e-mail me in last resort but you should check the shipping costs to/from France first because it might be more costly than a new device.

05/01/2015:

The whole detailed procedure for desoldering & soldering the chip is now available ->HERE<-.
The second procedure for building a working Flash image and programming it is available ->HERE<-.

.
Please note that the first release of each document (Rev. 05/01/15) shall be considered as a draft. As stated in these documents, any comment or remark is more than welcome.

Ouaps’s « Jojo » is not only a toy for your kid!

Ludo | 25 novembre 2012

Christmas is not too far away from now and Santa Claus already brought me a gift: a nice faulty electronic toy 🙂
When people usually take back the faulty device to the mall, I prefer to repair it myself as long as it’s possible (and also because I bought it from Amazon and I didn’t want to send it back since I could not find it elsewhere).
This toy called « Jojo pot de colle » (I only know its French name) was supposed to follow the kid, guided by a carrot shaped infrared remote control that the kid attaches to his wrist. Actually, it wasn’t able to do anything else than running round and round. So, my first guess was a battery issue: wrong! A motor issue: wrong too! So after opening it and re-soldering a broken wire with no luck, I’ve played with the oscilloscope around the IR receivers that the toy uses to move towards the kid. One of these receivers seemed to be faulty (no IR reception), but it was actually a PCB issue. These components pins are bent so much that one of them pushed the pad away from the single side PCB and broke the connection to the ground.
One more soldering later, the toy was working like it should have since the beginning.

http://dl.shibby.fr/blog.shibby.fr/Toy_repair/JojoPotDeColleRemoteControlProtocol.pdf

The war is not over!

Ludo | 19 octobre 2012
I just couldn’t stay with so many questions and so few answers, so come check back the protocol descritpion in the next few weeks 😉

I’ve made a scan of the RC-20 Instruction manual, since it’s not available anywhere else, maybe it will be useful to someone.

Trying to find RC-20 commands

Ludo | 23 septembre 2012
Well, I think the protocol description I’ve made is pretty much complete, now it’s time to try every other command than the ones sent by the RC-10 and see what happens (by « see what happens » I mean « pray that the transceiver won’t blow up »). I’ll write a simple program on a Renesas microcontroller that will convert UART frames sent from my computer with Docklight into a synchronous « SPI like » data frame to the TM-241.I’ll try to update this entry ASAP with some test results.

10/07/2012: Well, after trying to use the R8C/25’s integrated USART peripheral for days and a strong headache, I’ve finally capitulated and written a software protocol based on the Timer RA in « Pulse Width Measurement » mode. It uses the clock signal generated by the transceiver to send and receive data. That’s the good news.

The bad news is that the transceiver doesn’t seem to accept any command above 0x3F, so after all this hard work I still don’t know how the RC-20 sends its commands, which is a little bit frustrating.

I did not waste my time anyway since I’ve found the purpose of some other bits from the LCD indicators bit field, but I would have liked to find more about the RC-20…
I’ve updated the protocol specifications with my latest finds.
I’m interested by any information about the operation of the RC-20 (yes, this is an SOS).