Decoding Chinese RFID Ebay Auctions

Posted in Uncategorized with tags , , , , , on March 20, 2014 by brandon314

Some very basic (but very useful) notes regarding RFID products on Chinese ebay auctions for RFID readers. This includes wiegand receivers. This is mainly for the cheap RFID readers/cards/etc. found on e-bay.

  • If it says “ID” anywhere in the ad, 125Khz
  • If it says “IC” anywhere in the ad, 13.56Mhz.

 

The standards listed (14443A, M1Card, etc.) are used randomly even though the devices may not be compatible. It appears the fall-back is the ID/IC standard for whether your card is LF or HF. The likelihood of a dual-band reader existing on ebay is VERY VERY slim.

Ubiquti AirCAM Repair – Link but no GUI

Posted in Uncategorized with tags , , , on October 25, 2013 by brandon314

Hello all,

Quick note over here from the world of failing AirCAM’s. I recently had a 2nd failure of my exterior mounted AirCAM. Since the RMA process was coming up bunk I decided to attempt a repair myself. I run an electronics engineering lab so have access to equipment (hot-air reflow, metcals, etc.) 

The camera under repair is one I had die in operation about about 3mo of continuous use. The camera was exhibiting a condition where it would link up (sometimes at 100BaseT, always at 10BaseT) but I could never reach the GUI or do anything but SOMETIMES ping the unit (192.168.1.20). Flexing the PCB or agitating the camera didn’t seem to make a difference.

I opened up the camera (quite easy) buy removing the sun shield, unscrewing the lens cover, popping off the triangular face ring, and removing the black screws. Once removed, I could slide the camera/PCB board out of the body and engage in repair activities. The PCB/components are coated with what I suspect is an anti-moisture protector so make sure you have adequate airflow when doing any heating of the PCB.

Image

 

Image

 

Image

I reflowed the small BGA package (U3) and touched the rest of the board with the hot air JUST in case there was a poor lead-free solder connection. Once reflowed, the camera snapped back to life (able to access the GUI, etc.)

As I’ve had issues with BGA components before (especially when using lead-free solder) I am not terribly surprised to see problems here. I’m happy to see that static electricity didn’t kill this device (apparently that is another common failure). My last camera would transit packets but not receive them (similar issue?)

Interesting side note that the device PCB has a USB connector site that can be populated. Not sure what for, but it’s there.

Hopefully these notes treat someone well. If you don’t have access to the right tools, I can help re-flow your failed AirCAM (if out of warranty) as a last resort. Contact me for details.

 

 

Icom W32A Handheld Manual

Posted in Manuals, RF on May 21, 2013 by brandon314

ICOM_W32A_Manual

Basic Battery Isolation Using Solenoid

Posted in Automotive, Electronic Projects, Power on April 29, 2013 by brandon314

Dual Battery Isolater

Glenn Martin MT-1845 Tower Documentation

Posted in Infrastructure, Manuals, RF on April 3, 2013 by brandon314

I had a difficult time finding this documentation so I’ll post it here for anyone whom may need it in the future.

 

This is for a Glen-Martin (G-M) MT-1845 50ft crank-up ground-mount tower. This is the same tower found on their TT-1845 (trailer mounted 50ft tilt over tower), but with a base plate for direct ground mounting.

PDF Document for Base Plate/Concrete Requirements: Chb13-18

PDF Document for Tower Specification Drawings: MT-1845

 

HB-13-18

MT-1845 1

MT-1845 2

PIP-2424LC Pure Sine Inverter Charger Review

Posted in Infrastructure, Reviews on April 1, 2013 by brandon314

I recently purchased a PIP-2424LC inverter/charger w/ Solar charger off of ebay from the Taiwanese company MPPSolar.

Below is a review of the item (with photos).

 

We purchased two of these units, one with the network interface module, one without. Both of these units were connected to 24V DC AGM battery banks (two group 8D batteries in series each). They were independently powered from either phase of a 240V drop (each had their own 120V 30A breaker). 200A fuses were used with 00 wire on the DC inputs. The sine-wave from these units was actually quite clean (especially considering the design) and played well with all of our true-sine sensitive devices. We did find that during brownout, the device switched over at too low of a voltage (even though we set it to be 100V) and some servers/computers would actually drop while the switchover was happening. This obviously defeats the purpose of a battery backup inverter/charger for UPS use.

After ~6mo use, one of the units showed DC BUS FAIL and was emitting a terrible smell. It failed into AC only mode (inverter not functioning) so at least the computers stayed online. After working with the vendor (support@mppsolar.com) they advised us to remove the cover and photograph the internals. Below are what we found.

IMG_20130328_100408_052

 

These are two capacitors off the main DC bus right at the switching MOSFETS. It appears that poor wave-soldering caused intermittent connection, which lead to high resistance and when the units would drop into inverter mode, melting of the solder. These two capacitors were loose in the unit (had unsoldered/burned the leads off). The 3rd capacitor was loose but not fully removed.

 

 

 

 

 

 

 

 

IMG_20130328_100430_151

 

Wave solder screens under the capacitors were burnt, showing a clear indicator of high-resistance connection. The capacitors were still fully functional when tested.

IMG_20130328_100442_887

A shot of the PCB where the capacitors connect.

IMG_20130328_100458_808

 

A photo of the MOSFETS showing that they are all in-tact.

IMG_20130328_100517_852

Another shot of the MOSFETS on the other side, again all in-tact.

MPPSolar wanted us to ship them the PCB board so that they could then ship us a replacement (meaning even more downtime, even more expense, and us doing all of the labor in-house). Purchasing these units from outside the country is the risk you take and in this case, that was a bad choice.

 

In summary we determined that poor wave soldering on this unit resulted in premature failure. The difficulty in configuring the voltages at which the unit goes into changeover can be a large issue for people with sensitive electronics or applications where 100%  up-time is a requirement. I would suggest not to waste the money on these units as even though the tech support team is good with communication, you will find yourself shipping parts to/fro Taiwan on your own dime.

I would also HIGHLY suggest never using one of these units in a mobile application as the construction methods and soldering type is not adequately stable for longevity.

Elevation Profiles for Portland, OR (PDX) to Black Rock City, NV (BRC)

Posted in Uncategorized on December 10, 2012 by brandon314

For those of us who have naturally aspirated heavy vehicles, these graphs may be of some use.

Thanks to http://www.gpsvisualizer.com/elevation for the tool!

 

The standard route (I-5 South to Hwy 58 to Hwy 97 to K-Falls to Hwy 139 to Hwy 299 to Hwy 447 to Gerlach, NV) Shortest with most pre-elevation low-altitude driving (better MPG at lower altitudes).

Elevation 58 to 97

 

 

This route is very similar except travels up over 26 and directly onto 97 (lots of higher altitude driving and a fair amount of decent/climb. (Hwy 26 E to Hwy 97 to K-Falls to Hwy 139 to Hwy 299 to Hwy 447 to Gerlach, NV)

Elevation 26 to 97

 

This route is using Hwy 22 out of Salem. (I-5 South to Hwy 22 to Hwy 97 to K-Falls to Hwy 139 to Hwy 299 to Hwy 447 to Gerlach, NV) Not as much low altitude driving as the 58 route, but it does have a nicer climb profile.  I’ve done this route and it’s not too bad but you definitely notice running up around 3000-4000ft right off the freeway.

Elevation 22 to 97

 

This is the ever popular route that uses Hwy 58 but passes by SummerLake hot springs. (I-5 South to Hwy 58 to Hwy 97 to Hwy 31 to Hwy 395 to Hwy 299 to Hwy 447 to Gerlach, NV). The length is a bit longer than the K-falls route and has a few more random bumps with steep peaks along the way, but the SummerLake option is a nice one.

Elevation 58 to 31

Hope these are useful!

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