Saturday, October 22, 2011

iPad gadgets for geeks: iDVM



Redfish's iDVM iPad-enabled digital multimeter can help you troubleshoot all sorts of electronics by probing voltage, current and resistance. At $485, however, it is an expensive tool.

iPad add-ons
Redfish's iDVM digital voltmeter can help you troubleshoot electronics.

The iDVM connection box is a 4.6 x 2.8 x 1.1 in. device to which you attach the included electronic probes. It connects to the iPad via Wi-Fi; a blue LED light on the connection box shows that it's connected. It weighs 5.6 oz., making it smaller and lighter than a standalone multimeter.

Unfortunately, no alligator clips are included for connecting to circuits in tough-to-reach places, but it's easy to use your own.

To get started, you'll need to download the free iDVM app from the App Store. The app resembles a cartoon version of a handheld multimeter. There's a window for readings, a dial for choosing whether you want to measure voltage (from 0.4 to 300 volts), resistance (0 to 4 mega ohms) or current (0.1 milliamp to 4 amps). There's also a handy continuity tester that measures whether the circuit has a break in it.

There are icons for holding the reading at any point, displaying the minimum and maximum as well as changing the range of the readings. At any time, you can grab a screenshot (but not a video).

The software works in portrait or landscape mode. The former adds a graph of the readings over time, while the latter has a list of the program's saved files. At any time, you can set the iDVM to tell you the readings via audio, although the synthesized voice quickly gets annoying.

Once everything was set up, I attached the iDVM's probes to a new 9-volt battery and verified its reading with a standalone Radio Shack multimeter; the two readings agreed perfectly. I found that the Wi-Fi connection had a range of 85 feet.

I used the iDVM to troubleshoot a car stereo that shuts itself off with no warning while driving. After connecting the iDVM probes to the stereo's power cable, I drove around listening to the meter tell me the voltage readings until the stereo cut out; at the same time, the voltage reading dropped to zero. Sure enough, I found that the stereo's power connector was loose, causing an intermittent fault.

The rechargeable device ran for nearly 11 hours before its battery ran down, easily outlasting the iPad's battery. The iPad interface has a four-segment gauge that shows how much power remains in the iDVM's battery.

Bottom line

All in all, the iDVM transforms an iPad into a capable multimeter for everything from checking batteries to sniffing out an electronic fault. However, it costs about 10 times what a good handheld meter will cost.

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