Tag Archives: soldering

MintyBoost XL: Almost Finished!

Well, I finally drilled my PCB for my MintyBoost XL last night, and it was a great success. If you need PCB drill bits, order them from stevie66 on ebay. I got various sizes from 50 to 85, but I found the 65 to be the most useful. I used it to drill all but the largest holes on the board.

Flickr Tag Error: Call to display photo '5394561101' failed.

Error state follows:

  • stat: fail
  • code: 95
  • message: SSL is required

Once that was done, I soldered it all together. It came out very nicely. I struggled the most with the mint tin!

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Error state follows:

  • stat: fail
  • code: 95
  • message: SSL is required

I hooked it up and tested the input: about 2.3v. Then, I carefully tested the USB output power pins: 5.03V! This thing works beautifully.

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Error state follows:

  • stat: fail
  • code: 95
  • message: SSL is required

I found an issue with my implementation of this project, though. The LT1303 IC doesn’t support current above 200mA, so my phone rejects the charge after about 5 seconds. I found out you can request samples directly from Linear, so I’ll be trying out a 1302, and perhaps redesigning the board to use a newer generation chip I’m sampling from Linear Technology.

Overall, this is great for the intermediate electronics nerd who wants to take a circuit from board layout in Eagle to working semi-professional product! I had a lot of fun doing it, and making small modifications will be even more fun.


Making my own PCBs

I’ve always wanted to make my own PCB, so today is a special day for me.

This is for the MintyBoost XL, which is totally awesome. Now I just have to etch it, drill it, and solder all these little components onto it…

I used the instructions found here to create this little gem. They are very good, but I modified the method slightly. Instead of taping crap down, you just heat up the board like he says, carefully stick the paper to it toner side down, and start ironing for a few minutes, pushing hard and using the tip of the iron to go over every everything nice and hard. Also, cleaning is key – I used some 220 grit sandpaper and then acetone with a paper towel, and it turned out great.

The schematic is available here. All credit really goes to Robert Hunt though – it’s his design. Also, here’s my slightly modified parts list I ordered from Digikey for this project:

1 811-2042-ND INDUCTOR RADIAL 22UH 2A
1 LT1303CN8-5#PBF-ND IC DC/DC CONV STEP-UP 5V 8-DIP
1 3M5473-ND SOCKET IC OPEN FRAME 8POS .3"
2 CF14JT100KCT-ND RES 100K OHM 1/4W 5% CARBON FILM
1 1N5817DICT-ND DIODE SCHOTTKY 20V 1A DO-41
2 BC22AAW-ND HOLDER BATT 2-AA CELLS WIRE LDS
2 490-5401-ND CAP CER 0.1UF 50V Y5V RAD
2 P5112-ND CAP 220UF 6.3V ALUM LYTIC RADIAL
1 UE27AC54100-ND CONN RCPT USB TYPE A R/A GOLD

Total parts cost: $11.87.

Not too bad for a little DIY and fun. Board cost a few pennies.

UPDATE

I got tired of waiting for my FeCl in the mail, so I used some awesome instructions to take Muriatic Acid (also known as Hydrochloric Acid) from Lowes and Hyrdrogen Peroxide and mix ’em together with the PCB to etch it, and also yield a byproduct of Cupric Chloride, which is also a reusable etchant itself! And it did a fantastic job:

I made sure to find plastic containers that don’t react or melt when exposed to the acid – my tray was from Walmart and is PVC and my container for the leftover acid was an HDPE milk jug. So far, so good!