Two Passes, One Document: Collating a Flipped Scan with pdftk

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Scanning a double-sided document on a simplex scanner leaves you with two PDFs: the fronts in order, the backs in reverse. Interleaving them is one pdftk command with a backwards page range, and that part has never been the difficult bit. This piece works through the page-index arithmetic, a ten-minute test that proves the merge … Read more

From Censor to Atlas

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Secret military installations have always attracted rumours and speculation, although even people living nearby rarely knew much about them for certain. Today, with the internet and satellite imagery available through services such as Google Earth, keeping such facilities hidden has become considerably more difficult. Genuinely sensitive installations may still remain shrouded in secrecy, but the … Read more

Silvercrest 9149 Energy Consumption and Cost Meter

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The latest victim on the Teardown Bench is a budget Lidl plug-in power meter. It was sacrificed because its plastic parts had literally begun to crumble away. There is nothing particularly remarkable inside, but the subject of electrical power measurement itself is well worth a closer look! The Silvercrest 9149 energy monitor (also sold as … Read more

In Search of Garnets in the Börzsöny Mountains

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For most of us, the Börzsöny Mountains bring to mind andesite, old mines and volcanic landforms. Yet one of the range’s most distinctive minerals is a genuine gemstone: almandine, the iron-rich member of the garnet group. Most Börzsöny specimens would hardly belong in a jeweller’s window, but they are all the more interesting geologically. These … Read more

Restoring a Dried-Out Securit Liquid Chalk Marker

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Most Securit liquid chalk markers can be revived, as they feature water-based pigment ink and a valve-action system with a removable nib. The restoration steps: If the nib is frayed or permanently misshapen, Securit sells replacement nib sets, allowing you to keep using the marker as long as ink remains in the reservoir.

An Interesting Two-Transistor Relay Timer

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I came across the printed circuit board for this circuit completely by accident. It looked like an interesting and clever little design, and I had more than enough suitable parts lying around in my component drawers, including a pile of spare relays. So I decided to build one and measure what it could actually do. … Read more

Soldered Wire Connections: When They Are Safe, and When They Are Not

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Why a perfectly good solder joint can be a poor electrical connection – and what to use instead in household wiring, appliances and DIY projects. A twisted pair of copper wires, carefully soldered and wrapped in insulating tape, can stay electrically sound for decades. Open an old European junction box and you may well find … Read more

On the Teardown Bench: Radtel RT-470 – What’s Inside a Modern Handheld Radio?

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This time, the device on the teardown bench is not broken. My Radtel RT-470 is fully functional and gets regular use; it simply needed a thorough cleaning. For that reason, I did not take it apart any further than what you can see in the photographs. Even so, there is plenty to discover about how … Read more

How to eliminate duplicate photos from LrC

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There are many reasons why duplicates appear in your catalogs but even if you are careful while you import photos, encountering duplicates is inevitable. Here is how to use the plug-in Teekesselchen to find duplicates of photos. This is a fast duplicate finder plug-in for Adobe Lightroom using EXIF meta-data. It requires Lightroom 3.x, 4.x, … Read more