’s dumpster dive

Sparkfun’s dumpster dive is once in a few months event when they prep a limited amount of red boxes filled with rejects and some left over that they don’t feel as retail quality merchandize for various reasons, and put them on sale.

I bought these boxes on two occasions so far and I am reasonably pleased.
Let me share my experience.

  • Sale.
  • The sale takes place on select Fridays. In both occasions I learned about the sale when I visited the site to check out their blog section for new products, which they announce on every Friday morning.
  • The sale event will occur at 12 noon MT.
  • The whole lot will only last a couple of minutes, then the sale will be over.
  • Prior to Noon, you go to the site, login and go to the product page(DD-12012). There is no purchase button displayed yet. Precisely at 12 Noon, you start hitting the F5 key to refresh the screen. Once you see the Buy button, click on it to secure your purchase. If you can go through the purchase process in less than 2 minutes (confirming your address, shipping method and payment information and so so on – the fact you are already logged in will help expedite the process), chances are you will be rewarded with the order confirmation page.
  • Wait with a great anticipation for 3~4 days for the box to arrive.
  • Open the box and find out what is in there.
  • First purchase. (Feb 2014) – All parts listed were confirmed functional.
    • Pcduino v1 x1
    • PIC KIT2 compatible CANAKIT programmer x1
    • Vehicle diagnostic kit x1
    • Sonar module x2
    • FTDI USB-Serial converter (3.3V) x1
    • Stepper motor driver board array. I was able to separate 5 good boards while destroying 1 using dremel
    • A lot of electrolic capacitors
    • One comparator, One photo interrupter, One gap sensor, One ADC.
    • Half dozen of banana plugs
    • USB bluetooth dongles.
    • 3 pin rotary encoder x1
  • Second purchase
    • LCD module 24 chars x 2 lines
      It had 14pin connector. Using Arduino example sketch and pin out information I gathered from Internet, The module was confirmed functional. There is a two terminal pad on PCB which is obviously for backlighting and it looks like EL lighting. $10 value.
    • LCD module 16 chars x 2 lines
      There was a 14 pin ribbon cable coming out from the module. Again I used the pinout and Arduino Uno to confirm the functionality but this one did not work at the first time. It turned out the ribbon cable was broken, so I removed it and replaced with a header connector. The part is now working. $7 value.
    • Bleep drum version 1
      1) This assembly was in a bad shape. I suppose the kit was used in a class room environment or something, but who ever built the kit got the switch and stereo plug on the wrong side of the PCB and must have abondned the project. 9V battery holder and one of four studs were missing as well. Desoldering those multiple lead components was not a fun at all.
      2) I attached 9V battery and powered it up, hoping the LED will light up. Nothing happened and 78I05 was getting rather hot. Quick check on the output of the voltage regulator indicated something was loading down the VR really bad. Pop out the 8 pin dip and LED started to respond to button pushes. VR out was 5V. Oh, bad IC chip I thought and looked a t the part number on it. This is where real shocker camein. It said TA7015D, which is audio Amplifier. Wait a minute, the schematic I found on the Internet says this should be 4901 DAC! Both are 8 pin DIP IC but was the kit supplied with the wrong IC chip?
      3) So I replaced a chip with 4901. I purchased it from when I ordered other parts. Now it seems to be working $50 value?
      4) If the kit was supplied with a wrong chip, then the poor guy who attempted to build it had no chance of this working.
      5) I also feel bad for people who is coming to electronic kit building these days. In my days, components were large. Solder pads were large and solder melting temperature was low due to lead in the solder. It is more difficult to work on PCB soldering even for me who I consider somewhat experienced in soldering.
      6) Bleep Drum is fun!
    • LPC 1768-H blue board
      1) This is a retired Arm cortex board on Sparkfun site. NGX saite is still selling it for $50 or so.
      2) When powered, the test LED was dim and there was no initial booting action where the LED was supposed to blink four times. Scoping the LED output confirmed it was blinking too fast. Somebody must have tried to download a blinky program but with a wrong timer value.
      3) I tried to connect to UART0 with USB-serial cable (using just black-GND, Green-RX0, White-TX0, no connection to red wire) connection after downloading flashmagic. Rebooting while sw press started a bootloader and I was connected. I reinstalled USB secondary bootloader.
      4) Now the USB bootloader started to work. I was able to drag and drop the initial bin file to the board. The board is now reinstated to its original shape. When powered up, LED blinks four times and wait to be programmed.
      5) But I don’t think I keep looking at this board because these days there are so many other options to jump into Arm micro controller more cheaply and easily . I am experimenting with FRDM-KL-25Z with mbed tool chain and its incredibly easy to use. Cypress PSoC now sells $4 board that comes with USB serial interface that can be snapped off for dedicated USB-UART cable afterwards. What a world are we living in?
    • Atmega 328P DIP
      1) Pins were all mangled up so I need to straighten them using a pair of tweezers. Popped into ISP programmer that I hacked with Arduino nano but AVRdude can not read the content. Its either a)broken, b)fuse is configured so can not be programmed without paralell programmer or c)fuse is set to use external crystal.
      2) Out of whim, I popped out the 328p from Arduino uno that I had and placed the 328p in question into Arduino board, loaded the blinky program and on-board LED started to blink. So this must be a 328p with arduino bootloader preloaded. $6 value.
    • More Atmega micro controllers (4 of them)Those are all SMT components. I probably would not be able to use them
    • SC300 wifi module x5
      This looks fantastic but I don’t know how I can use them in this SMT pinouts.
    • Header pins.I received about two dozens of solid header pins. It turns out a perfect fit for my NRI (National Radio Institute) Lab Trainer’s terminal pins which were too loose to connect jumper pins to. So I broke up these header pins to single pins and soldered on top of terminall pins on my trainer. Now the jumper wires slide into it very snuggly. The 35 years old electronics lab trainer regained a new life. Nice.

Will I try the dumpstar again? Maybe I will. The process of troubleshooting seemingly non-working product has some attraction in it.

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