Archives for category: Android

I recently had to get rid of my rarely-used oscilloscope due to space restrictions and started looking at alternatives. The handheld devices started from about $70, but had known of some PC kits.

I thought, couldn’t I just use the input for my PC sound card? So came across the Poor Man’s Oscilloscope. I also knew of $300 iPad oscilloscope, which was crazy money.

Sat lonely in my box of old electronics, however, was a upgrade-made-redundant Android device. A brainwave hit and I set about making my $0 oscilloscope. Here’s a video explaining it:

How to Build

The probe is a very simple modified mic and headphone set with a potential divider and some crocodile clips. You will need:

  • Android phone with OsciPrime Oscilloscope Legacy
  • 4 pole 3.5mm jack (e.g. a handsfree set that comes with a phone)
  • 2 resistors in a ratio of roughly 1:10
  • Probes (I used crocodile clips) with some cable (multicore is best)
  • Perfboard (optional – you could solder directly)
  • Heat-shrink / insulation tape

Below is a diagram of how to wire. The potential divider simply reduces the voltage in to the device, lowering the risk of killing the mic-in circuit in the phone.

The circuit is very basic and you could make it all in under an hour, but it’s certainly not fool proof. A more complex alternative using op amps can be found on this Instructable.

You may also run in to the problem of the headphone wire being annoyingly coated. I simply burnt these with a butane lighter, but you can read more on the technique here.

If you also build one, would be great to hear how you get on.

20120715-102717.jpg

I’d always wanted my very own arcade cab, but never had the space. So, when I had a loose weekend, an old Android device and some MDF I had to make this miniature cab-shaped phone stand.

Video at the bottom of this post.

The construction was pretty simple: All MDF was cut from a template with a jigsaw, then glued and clamped, sanded and finished with black spray paint.

For the paint I used graffiti paint that you get from art shops. It’s much higher quality than Odds ‘n’ Ends or other automotive paint you might get, so highly recommend sourcing some.

The artwork was printed from vector to semi-gloss photo paper using an inkjet. This was glued on or stuck with double sided tape. I used Pritt Stick, which as you can guess, wasn’t very strong, so peeled. If I were to redo this now I’d use sticker sheet.

The device is a Orange San Francisco (aka ZTE Blade), which is a lovely cheap device with an OLED screen (later models had less fantastic screens). It’s fully rooted and running Cyanogen Mod 7.

The MAME port is called MAME4Droid (Marketplace) and is, again, excellent. It’s based on an older MAME version, so doesn’t support all ROMs. But you’ll only be running ROMs for those machines you own, right? RIGHT?!

The Wimote hooks up over Bluetooth using Wiimote Controller (Marketplace). This is a bit of a hack as it sends buttons by appearing as a software keyboard to apps. You may also need to manually find and input the BT address of the Wiimotes by using another app (see help in Wiimote Controller app).

You can configure the buttons in MAME4Droid. All except coins, which you’ll need to do manually with an on screen button.

And here it is in action: