Basic 3.3v power supply / regulator

Not all Arduinos can supply the 3.3v that the NRF24L01+ needs directly. For example, the Nano only supplies 3.3v if powered via USB. To get 3.3v from a power source (such as what you would use to power the Arduino, or the 5v output of the Arduino), all you need is a regulator and a capacitor. For this, I used a LD1117v33 ( (the LM1117v33 ( is pretty much equivalent) together with a 10uF capacitor.

Basic 3.3v power supply / regulator »

Using the Nordic nRF24L01+ with a Seeeduino Mega 1280

The nRF24L01+ module (sources ( is a really cheap & easy way to achieve wireless communications. With the internal antenna, the reach is about 100m (open area), with an extra antenna it’s apparently 1100m+. One popular Arduino library for it is the Mirf library ( Connections Required pins with fix locations / can’t be moved: Arduino Uno / Nano ( MISO -> 12 MOSI -> 11 SCK -> 13  Seeeduino Mega 1280 (archive.

Using the Nordic nRF24L01+ with a Seeeduino Mega 1280 »

Painful crawl errors?

HELP! MY SITE HAS 939 CRAWL ERRORS!!1 I see this kind of question several times a week; you’re not alone - many websites have crawl errors. 404 errors on invalid URLs do not harm your site’s indexing or ranking in any way. It doesn’t matter if there are 100 or 10 million, they won’t harm your site’s ranking. ( In some cases, crawl errors may come from a legitimate structural issue within your website or CMS.

Painful crawl errors? »

Ultrasonic-triggered MP3 player with Arduino

This small MP3 player is triggered when the ultrasound sensor notices someone nearby for a longer period of time (must be closer than 70cm for >0.9s). The hardware uses: Arduino Uno R3 ( Seeed Studio Music Shield v1 ( and micro-SD card with a MP3 file (shop ( HC-SR04 ultrasonic distance sensor (eg shop (, they’re cheap) Breadboard, speakers, jumper wires Optional: LED, 330 Ohm resistor (to show that it’s still running) I hacked the Music Shield to include risers for some of the pins.

Ultrasonic-triggered MP3 player with Arduino »

Spaces in URLs

Q: Does Google allow spaces in URLs? A: Yes! But because other sites sometimes have problems with linking to URLs with spaces, we generally recommend using dashes (-) or underscores (_).

Spaces in URLs »

Sample page with lorem ipsum

This is just a sample page There’s really nothing hidden in the content here. No need to check the first letters of anything here and check for rot16. Images from ( Here’s a section Lorem ipsum dolor sit amet, consectetur adipiscing elit. Zeno autem, quod suam, quod propriam speciem habeat, cur appetendum sit, id solum bonum appellat, beatam autem vitam eam solam, quae cum virtute degatur. Theophrastum tamen adhibeamus ad pleraque, dum modo plus in virtute teneamus, quam ille tenuit, firmitatis et roboris.

Sample page with lorem ipsum »

Hackers stealing your PageRank

The last time I wrote about a hacked site, it was using a redirect that sent some users to a different site. This kind of hack is pretty common (even though it’s usually not as complex as mentioned in that post), it leverages the sad fact ( that users are often easy to trick and not browsing with protection (or a current browser ( A different angle of attack is to redirect only search engine crawlers to a different site.

Hackers stealing your PageRank »

Seeing nofollow links in Google Chrome

Here’s a simple trick to view nofollow links in Google Chrome. Just drag and drop the following link to your bookmark bar and hit it whenever you want to see links with the rel=nofollow HTML microformat: Nofollow? This bookmarklet inserts a tiny bit of CSS into the top of the page you’re currently viewing. The CSS is similar to that which is used in other nofollow highlighting methods ( a[rel~=nofollow] { border:1px dashed #852!

Seeing nofollow links in Google Chrome »

Confirm that you're using Analytics on all pages

Here’s something from my mailbox - someone wanted to know how he could crawl his site and confirm that all of his pages really have the Google Analytics ( tracking-code on them. WordPress users have it easy, there are plugins that handle it automatically. Sometimes it’s worth asking nicely :) - let me show you how I did it. As a bonus, I’ll also show how you can check the AdSense ID on your pages, if you’re worried that you copy/pasted it incorrectly.

Confirm that you're using Analytics on all pages »

Running Firefox in parallel

Sometimes it would just be great to have multiple instances of Firefox running at the same time. Some web applications just love to eat memory in Firefox, some web pages go crazy if you have JavaScript enabled and sometimes you just want different sets of cookies to let you manage two accounts at the same time. I’ve been trying to do that for years and did the most exotic things to make it happen.

Running Firefox in parallel »