Artificial Intelligence Church

In the world of electronics we have impedance; the combination of all forces which oppose the flow of electric current. Often times we have circuits with different impedances, 50 ohms for RF, or 75 for cable TV. It’s pretty important to use the right coax in these circuits, else you’ll be wondering why your RG-58 antenna feed line doesn’t give you anything good to watch.

It’s pretty important to match impedances when connecting different circuits. Apart from the obvious flaws such as a 50 ohm load blowing up a 300 ohm amplifier, there are subtler things such as signal reflection and destructive interference which might just be enough to break whatever it is your playing with. RF mosfets are not cheap! But how could we match impedances? Well we could always use a transformer, but those are rather expensive and bulky. What if we only have a box of resistors to play with? Well, we could build an attenuator! Most of you probably know what an attenuator is; if not, it’s a de-amplifier. Simply put, it’s a circuit which reduces the strength of a signal. Often these are called ‘pads’ in the RF world, and the pad most often used is the pi pad. By looking at the network’s schematic it becomes rather obvious *why* we call it that.

It looks like a π.

Now our guests want a 50 ohm signal attenuation of 3dBm, or 50%. Let’s pick some toppings for our pi then, shall we?

When Z=50, R1 and R3 equal…

[292.4 ohms].

Now R2 equals…

[17.61 ohms]

Well that was a pain. Luckily, there’s a cheat sheet for this.

So now we have our values, and assuming a 50 ohm load everything should work just fine. But wait! Somebody F*cked up and put a 300 ohm feed line on the end of the pad! Crap. Let’s look at the resistance values of the network now, from A to ground. I’m assuming you should know how to calculate resistances…

…105.7 ohms. That’s near double the 50 ohm input impedance and is going to wreak all hell upon the other circuitry. Sure, it does its job of reducing the signal 3dBm but still.

Now here’s the neat thing. Let’s pick some new resistor values so that we attenuate by 10dBm, or about 90%. According to our cheat sheet we’d need 71.75 ohms of attenuating resistance and 96.25 ohms to ground on either end. What’s the impedance mismatch now?

57.78 ohms, or 7.78 away from 50. That’s a lot better than before, and should actually be usable as an impedance matching network. Sure, you lose 10dBm or about 90% of your signal strength, but that’s nothing that can’t be compensated for by putting a Class-C amplifier in series with the attenuator. Even with an active component it’s still cheaper and smaller than a transformer. What I’m trying to prove here is that pi pads can be used as the poor man’s impedance matcher; as attenuation goes up the impedance mismatch goes down.

What’s nice about resistive pi pads is that they are ultra-wideband; since there are no reactive components this network will always attenuate by 10dBm and always match the impedance by 7.2 ohms. An inductive network such as a transformer might not work at both 200kHz and 200MHz. Actually, it certainly won’t work! Capacitive networks would have the same limitations.

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Last year’s beautiful Makey Awards, designed by MakerBot artist-in-residence Jonathan Monaghan

We are thrilled to announce the 2nd Annual MAKE Magazine Industry Maker Awards (aka the “Makeys”)

Over the next 16 weeks, leading up to swanky award ceremonies at Maker Faire New York 2012 (Sept 28, 29), we’ll be profiling, here on MAKE, 12 companies that have shown outstanding support for independent maker/hacker culture over the past year. Four companies/products will be nominated in four categories, and a public poll will determine one winner in each category.

In 2011, we gave 3D-printed Makey statues to the follow recipients:

Microsoft Kinect – Most Hackable Gadget
PanaVise – Most Repair Friendly
Parallax, Inc. – Best Education/Outreach program
Lego – Best Product Documentation

As part of the program, a “Maker Hero” award will also be presented to an individual in the DIY/DIWO community who has made an outstanding contribution to the cause of maker-related education and/or open access to technology. The first award was presented last year to Mitch Altman, for his tireless work in building collaborative “hackerspaces” around the world and in teaching people the joys of hobby electronics and collaborative technologies.

The Makeys are being announced today at Maker Faire Bay Area. As this movement grows, mainstream companies are starting to take makers more seriously as a market segment. MAKE hopes that profiling and celebrating companies that are “getting it,” and giving four of them awards of appreciation, will help fuel their adoption of more open, accessible, user-friendly, and modifiable products.

Stay tuned for the announcement of the first 2012 Makey nominee, Monday, May 28, here on makezine.com. And you can nominate companies and track The Makeys process leading up to Maker Faire New York on The Makeys landing page. Feel free to also nominate companies and worthy maker heroes in the comments below.

After winning last year’s Most Repair Friendly category, for their indispensable electronics vises/circuit board holders, PanaVise added a Makeys “seal of approval” to their product boxes. SO cool!

Last year’s Makey award was designed by MakerBot artist-in-residence Jonathan Monaghan. We want to render the award in a different maker-friendly medium every year. We already have a good idea of what we’d like to do, but we’d love to take suggestions, too. What form would you like to see a Makey take?

There’s no question that Apple has their industrial design down pat; comparing a cell phone charger made by Blackberry or Motorola to the tiny 1-inch-cube Apple charger just underscores this fact. [Ken Shirriff] posted a great teardown of the Apple iPhone charger that goes through the hardware that makes this charger so impressive.

Like most cell phone chargers and power supplies these days, Apple’s charger is a switching power supply giving it a much better efficiency than a simple ‘transformer, rectifier, regulator’ linear power supply. Inside the charger, mains power is converted to DC, chopped up by a control IC, fed into a flyback transformer and converted into AC, and finally changed back into DC, and finally filtered and sent out through a USB port.

The quality of the charger is apparent; there’s really no way this small 1-inch cube could be made any smaller. In fact, if it weren’t for the microscopic 0402 SMD components, it’s doubtful this charger could be made at all.

Comparing the $30 iPhone charger of a cheap (and fake) iPhone charger, the budget charger still uses a flyback transformer but there are serious compromises of the safety and quality. The fake charger doesn’t use a power supply controller IC and replaces the four bridge diodes for a single diode to rectify the AC; a very efficient cost-cutting measure, but it does lead to a noisier power supply.

There’s also the issue of safety; on the Apple charger, there is a (relatively) huge physical separation of  ~340 VDC and your phone. With the off-brand charger, these circuits are separated by less than a millimeter – not very safe, and certainly wouldn’t be UL approved.

It’s worth pointing out that [Ken] compares a similar $7 Samsung charger favorably to the $30 Apple charger. Both are functionally identical, but Apple also has their  marketing down pat, to say the least.

Tip ‘o the hat to [George] for sending this in.

We’ll admit that we haven’t been following Minecraft like we used to; its been a while since we’ve seen something amazing in Minecraft, but [eloraam]‘s 6502 emulator (part of her RedPower Minecraft mod) takes the cake.

The RedPower mod adds a lot of industrial technology to Minecraft. Pumps, solar panels, and pneumatic tubes to move blocks around are the staple of this mod, but with the addition of a fully emulated 6502 computer, Minecraft moves from an anachronistic medieval-themed steampunk aesthetic to a full-on machine age, mainframes everywhere style.

The heart of the 6502 portion of the RedPower mod are three craftable blocks; a CPU, a monitor, and a disk drive. All these blocks are connected together with ribbon cables and can interact with other blocks in the Minecraft universe. The CPU is an emulated 6502, with a few instructions borrowed from the 65816 and the addition of MUL and DIV. It’s possible to program this computer in assembly, but [eloraam] a Forth interpreter with the OS to make programming a little easier.

It’s been almost two years since we first saw the beginnings of a CPU made in Minecraft, but this mod takes everything to the next level. In actuality, this isn’t very different from the game [notch] is currently working on; both feature an emulated 80′s era computer that can do all your in-game bidding. We can’t imagine anything better to get us hooked on Minecraft again, and we’ve got to commend [eloraam] for some seriously awesome work.

After the break is a 23-minute tutorial on the functions of the RedPower CPU, as demonstrated by Minecraft aficionado [direwolf20].

In a decision we completely agree with, these industrious young women decided that playing in the rain would only be more fun if it included an interactive light show. They wanted the rain itself to cause LEDs in their umbrella to light up. To achieve this, they put piezo sensors on each of the 8 panels of the umbrella. When that panel gets hit, its LEDs light up. You can see in the video after the break that it was quite effective.

Their next step should be to somehow increase the resolution to be similar to this one, while maintaining interactivity with the rain. How would you sense rain drops with more definition though?

[via Adafruit]

Maker Faire Bay Area opened Saturday with an excited rush of the gates. Here are some of the favorite things I saw from the robotic orchestra to Christian Ristow’s metal face and the lock picking workshop organized by Christina Pei. There’s a solar oven popping popcorn and a village made from masking tape with a colorful backdrop of coat hangers. It was an amazing day.

Maker Faire Bay Area opened Saturday with an excited rush of the gates. Here are some of the favorite things I saw from the robotic orchestra to Christian Ristow’s metal face and the lock picking workshop organized by Christina Pei. There’s a solar oven popping popcorn and a village made from masking tape with a colorful backdrop of coat hangers. It was an amazing day.

[Matthew Riese] got frustrated waiting for the future to arrive so he could have his flying car. He decided to take things into his own hands and construct the closest thing he could. This turned out to be a hovercraft. Not only that, but he thought that the most fitting shape for this thing would be a DeLorean.  We can’t say that we disagree with him. Unfortunately, there isn’t a whole lot of information on his build. There is this cool video on his kickstarter page (don’t worry, he got funded back in 2010). To make up for the fact that the build information is sparse, we’ve found you some plans to make your own hovercraft. Just add whatever shape body you want, though we have some suggestions.

[via Makezine]