Automatic Audio Leveling Circuit Makes Scanning More Fun

June 29, 2014 by Adam Fabio 17 Comments

alan-scope1

[Alan’s] friend came to him with a problem. He loved listening to his scanner, but hated the volume differences between stations. Some transmitters would be very low volume, others would nearly blow his speakers. To solve the problem, [Alan] built up a quick automatic leveling circuit (YouTube link) from parts he had around the lab.

[Alan’s] c alan-scope2 ircuit isn’t new, he states right in the video that various audio limiting, compressing, and automatic gain control circuits have been passed around the internet for years. What he’s brought to the table is his usual flair for explaining the circuits’ operation, with plenty of examples using the oscilloscope. (For those that don’t know, when [Alan] isn’t building circuits for fun, he’s an RF applications engineer at Tektronix).

Alan’s circuit is essentially an attenuator. It takes speaker level audio in (exactly what you’d have in a desktop scanner) and outputs a limited signal at about 50mv peak to peak, which is enough to drive an auxiliary amplifier. The attenuator is made up of a resistor and a pair of 1N34A Germanium diodes. The more bias current applied to the diodes, the more they will attenuate the main audio signal. The diode bias current is created by a transistor-based peak detector circuit driven off the main audio signal.
But don’t just take our word for it, watch the video after the break.

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Hacklet #5 – Hackerspaces And DIY Laptops

June 27, 2014 by Adam Fabio 13 Comments

Did you know that Hackaday.io has a hackerspace index? That’s right, you can enter your local hackerspace’s info, pictures, videos, and social media links. Members and crew can link their hackaday.io profiles and drop comments about their latest projects.

The map up at the top of the hackerspace index’s page is interactive too – zoom in on your country and local area to see any spaces nearby. It’s like one-stop shopping for awesome. Well, except that this awesome is free.

It really is great to see all the pictures of spaces large and small. Some of the most stunning shots are from c-base, in Berlin, Germany. Founded in 1995, the c-base crew have created an incredible space. Take a look at the workstation in the photo. Is it Steampunk? Matrix-punk? Heck no, that’s 100% c-base.

Do It Yourself Laptops

You don’t have to be Bunnie Huang to build your own laptop. All it takes is some time, ingenuity,and a good hot glue gun.

Our first laptop is actually inspired by Bunnie’s Novena. The OpenTech-Laptop uses two binders as it’s shell, but inside hides some decent computing power. [OpenTech] used a miniITX motherboard with an ATOM N2800 CPU. The screen came from an old laptop (long live matte 4:3 screens!) [OpenTech] even hand wired a Low Voltage Differential Signaling (LVDS) cable so the motherboard can push those pixels. A wireless keyboard, hard drive, and speakers round out the build. [OpenTech] is still looking for a portable power solution.Why not follow Bunnie’s lead and grab some R/C Plane LiPo batteries, [OpenTech]?

Next up is a MiniBSD laptop computer created by [Jaromir]. MiniBSD is based on RetroBSD, a PIC32 based BSD single board computer. Rather than use a premade platform like the Fubarino, [Jaromir] laid out his own board with everything he wanted – a microSD socket, SDRAM, real-time clock, and all the trimmings. He then added a graphical LCD, a LiPo battery, and a sweet retro keyboard from an old Czech computer company called Tesla. [Jaromir’s] next task is a 3D printed case. The only problem is the case is 2cm wider than his current printer’s bed!

You didn’t think we’d leave the Raspberry Pi out, now did you? Laptop-pi is [Bram’s] project to convert an old DVD player (remember those?) into a Pi Laptop. Not only did [Bram] build a QWERTY keyboard from scratch on perfboard, he also hacked together an on-screen keyboard so he can type with just a D-pad. He’s currently fighting with a dodgy audio amp, but we’re sure that’s just a temporary setback. We think Laptop-pi will be a killer portable for retro gaming!

That’s it for this week’s Hacklet, stay tuned for next week when we bring you more of what’s happening at Hackaday.io!

Beams Of Light: An Oscilloscope Demo

June 27, 2014 by Adam Fabio 11 Comments

beamsoflight

The demoscene is alive and well, with new demos coming out on a multitude of platforms, including oscilloscopes. Beams of Light is a new demo released at @party in Boston by [TRSi]. Beams isn’t the usual .EXE file format for PC based demos. It’s distributed as a 4 channel wave file. The rear left and right channels are stereo audio. The front channels, however, are vector video to be displayed on an oscilloscope in XY mode.

Beams of Light isn’t the first demo to use an oscilloscope. Youscope and Oscillofun preceded it. Still, you can see [TRSi] pushed the envelope a bit with his creation. He used Processing and Audacity to create the vector video, and his own line tracing algorithm to reduce flyback lines.

[TRSi] included an updated copy of a python based oscilloscope emulator so you can play the demo even if you don’t have the necessary hardware. We wanted to run this the right way, so we powered up our trusty Tektronix 465 and hooked it up to a 1/8″ stereo plug.

Sure enough, the demo played, and it was glorious. We did see a few more retrace lines than the video shows. This could be due to our scope having a higher bandwidth than the 10MHz scope used in the YouTube video. XY demos are one of those rare cases where an analog scope works much better than a low-cost digital scope. Trying the demo on our Rigol ds1052e didn’t yield very good results to say the least. Sometimes good old phosphor just beats an analog to digital converter.

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The Basics Of Frequency Modulation

June 26, 2014 by Adam Fabio 7 Comments

fm-modulation

[brmarcum] takes us back to analog building block basics with his Frequency Modulation and Demodulation tutorial. Frequency Modulation (FM) sounds simple at first, but understanding the electronics behind modulation and demodulation of an FM signal can be confusing. We’ve covered the basics before, but FM is so tightly associated with broadcast radio that searches often become muddled with references to RF, stereo, antennas, and transmitters.

[brmarcum] hopes to fill that gap with a simple circuit that modulates an audio signal to FM, then demodulates and amplifies it to be played on a small speaker. He used a Digilent Analog Discovery kit in his experiments, but an oscilloscope (an older analog scope would be perfect here) would work for output. Signal generation duties could easily be handled by a 555 circuit at the low end, and a computer sound card at the higher end.

[brmarcum] obviously put some time into his tutorial, but it’s not a tome of FM modulation. He’s broken down the modulation and demodulation circuits into their basic op-amp stages with examples of what the signal should look like on a scope after each stage. That’s the beauty here. By building and testing each section, anyone new to analog can learn how things work. In places where the theory behind what’s going on gets too in-depth for an Instructable, [brmarcum] gives links to Wikipedia.

Here Come The RGB LED Clones

June 25, 2014 by Adam Fabio 20 Comments

ws2812 and clones timing

It seems like every third project on Hackaday uses WS2812 RGB LEDs in some way. We all love our blinkenlights, and bright, cheap, serial controlled RGB LEDs are the bees knees.

As with all products these days, competing manufacturers have discovered the huge market for these things, and clones are now available. [Tim] recently took a look at the PD9823, as well as three versions of the WS2812. [Tim] is considered something of a WS2812 guru here at Hackaday. You might remember him from his WS2812 driver optimization article, which should be required reading for any WS2812 hacker.

As many of us know, the timing characteristics for these LEDs can be a pain to work with. The values also differ between the WS2812S and WS2812B. [Tim] discovered that the new through hole WS2812D parts are different yet again, though rather close to the B parts. The PD9823’s designers must have studied the WS2812’s closely, as their 190ns time base falls directly between WS2812S 166ns time and the 208ns time of the WS2812B. The PD9823 also requires a slightly longer reset pulse.

The takeaway is that well written drivers such as [Tim’s] should have no problem with the new parts, but compatibility is something to keep in mind as more clones hit the market.

Drones And Robots Come Out To Play At Sparkfun’s 6th Annual Autonomous Vehicle Competition

June 24, 2014 by Adam Fabio 9 Comments

Sparkfun AVC 2014

Sparkfun Electronics held their 6th annual Autonomous Vehicle Competition last weekend, and this year was bigger than ever before. The action was at Boulder Reservoir in Colorado, but anyone could follow along (with a few technical difficulties) on the YouTube LiveStream. (Part 1), and (Part 2).

The story of the day was Team SHARC’s Troubled Child, which won the ground vehicle doping class. Rather than mess around with miniature cars, Team SHARC built their ‘bot out of a freaking Jeep, a 1986 Jeep Grand Wagoneer to be exact. Troubled Child had no problem getting around the course. One could say it carried the entire team. Literally – the rest of Team SHARC’s robots are riding along on top of Troubled Child in the picture up there.

There was also plenty of action in the aerial competition. Sir Crash-a-Lot was the first drone to find a watery doom at Boulder Reservoir. The last we saw of it on the stream, the team was looking for some divers.

Aircraft can not be hand launched at the AVC. Not a problem for rotary-winged vehicles, but this rule has led to some interesting solutions for fixed wing aircraft. The disguised “Team Falcon” showed up with an incredible compressed air launcher, which used a gallon water jug to fire their delta-winged plane to a clean run. Team Karma550 wasn’t quite as lucky, with their helicopter crashing hard, and throwing up quite a bit of smoke.

We’re still waiting for more detailed results, but if you want the full scores, they are available on Sparkfun’s AVC scoreboard page.

The 200 LED Ring Clock

June 24, 2014 by Adam Fabio 9 Comments

There are LED clocks, and then there are LED clocks that can blind you from 30 paces. [Stiggalicious’s] LED ring clock is of the latter variety. 200 WS2812B/Neopixel RGB LEDs drive the ring clock to pupil searing levels. The clock runs on ATMega1284P, with timekeeping handled by an NXP PCF8563 real-time clock chip. Code is written in Arduino’s wiring language using Adafruit’s Neopixel library.

Building the clock with a single Printed Circuit Board (PCB) would be both expensive and wasteful. [Stiggalicious] cleverly designed his clock to be built with 8 copies of the same PCB. Each board makes up a 45° pie slice of the ring. All 8 PCBs have footprints for the CPU, clock chip, and other various discrete parts, but only the “master” section has these parts populated. 7 “slave” sections simply pass clock, data, power and ground through each LED. He used Seeedstudio’s board service to get 10 copies of his PCB made, just in case there were any mistakes.

[Stiggalicious] rolled the dice by buying exactly the 200 LEDs he needed. Either he got really lucky, or the WS2812 quality testing has improved, because only one LED had a dead blue LED.

If you’d like to find out more, [Stiggalicious] gives plenty of details in his Reddit thread. He doesn’t have a webpage setup for the clock but he’s uploaded his source code (pastebin link) and Altium schematic/PCB files (mega.nz link). We may be a bit biased, but hackaday.io would be a perfect spot for this or any other project!