The Factory Of The World – Hackaday Documentary On The Shenzhen Ecosystem

July 27, 2015 by 20 Comments

When it comes to manufacturing, no place in the world has the same kind of allure as the Pearl River Delta region of China. Within just an hour-long train ride, two vastly different cultures co-exist, each with its unique appeal that keeps attracting engineers, entrepreneurs, and hustlers alike. On the mainland side, cities like Shenzhen and Guangzhou bring the promise of cheap components, low-cost contract work, and the street cred of “having done the Shenzhen thing.” And on the island, the capitalist utopia called Hong Kong glows with all of its high finance and stories of lavish expat lifestyles.

As the “new” China evolves, it seems like it’s exactly the convergence of these two cultures that will bring the biggest change—and not just to the area but to the whole world. Still, understanding what exactly is going on and what the place is really all about remains a mystery to many. So, this June, we jumped on the bandwagon and headed east, trying to get our own feel for the whole thing.

Here’s what we came back with…

Continue reading “The Factory Of The World – Hackaday Documentary On The Shenzhen Ecosystem” →

Make A Microphone Out Of A Hard Drive

July 27, 2015 by 6 Comments

[Rulof Maker] has a penchant for making nifty projects out of old electronics. The one that has caught our eye is  a microphone made from parts of an old hard drive. The drive’s arm and magnet were set aside while  the aluminum base was diagonally cut into two pieces.  One piece was later used to reassemble the hard drive’s magnet and arm onto a wooden platform.

v2_micThe drive’s arm and voice coil actuator are the key parts of this project. It was modified with a metal extension so that a paper cone cut from an audio speaker could be attached, an idea used in microphone projects we’ve previously featured. Copper wire scavenged from the speaker was then soldered to voice coil on the arm as well as an audio jack. In the first version of the Hard Drive Microphone, the arm is held upright with a pair of springs and vibrates when the cone catches sound.

While the microphone worked, [Rulof] saw room for improvement. In the second version, he replaced the mechanical springs with magnets to keep the arm aloft. One pair was glued to the sides of the base, while another pair recovered from an old optical drive was affixed to the arm. He fabricated a larger paper cone and added a pop filter made out of pantyhose for good measure. The higher sound quality is definitely noticeable. If you are interested in more of [Rulof’s] projects, check out his YouTube channel.

Continue reading “Make A Microphone Out Of A Hard Drive” →

Hackers Measure Cable Lengths With Time Domain Reflectometers

July 27, 2015 by 12 Comments

[android] has built up a fast edge pulse generator for time domain reflectometry (TDR). TDR is a neat technique which lets you measure cable lengths using electrical signals and can also be used to locate faults within the cable.

TDR works by sending a pulse down the cable. When the pulse reaches the end of the unterminated cable it is reflected back to the source. By monitoring the delay between the original pulse and its reflection you can determine the length of the cable. We’ve seen projects that use TDR before, and it’s often used in telecoms industry to locate faults in long cable runs.

You can try TDR in your lab using only a scope to observe the delay and a function generator to create the pulse. However, the technique works a lot better with pulses that have very fast rise times. So [android] built a fast edge pulse generator based on [w2aew]s design. Then added googly eyes for good measure. His build works great and is a nice demonstration of the technique.

Hackaday Prize Entry: Superb Audio With The Teensy

July 26, 2015 by 16 Comments

The Raspberry Pi and Teensy 3 both have I2S interfaces, and that means these boards can be used to play very high quality audio. A codec and an I2S interface is one thing, but turning that digital stream into a quality analog output is another thing entirely. You need only look at audiophile forums for enough mis- and disinformation for that evidence.

For his Hackaday Prize entry [William Hollender] is building an audio board for the Teensy 3.x. It features very high-end opamps, the right filters, and the correct topology to turn a digital audio stream into an analog signal that would please the most temperamental ear.

The Teensy Super Audio Board uses the Cirrus CS4272 audio codec chip, a high quality chip that can handle sample rates of up to 192kHz at 24 bit depth. This chip doesn’t include the analog input and output buffers, and this means [William] has quite a build in front of him. This means using high quality opamps, low noise power supplies, and knowing how to build a circuit and measure its noise.

So far, the tests revealed incredible dynamic range, flatness, and frequency response of this tiny little board. It also works with the Raspberry Pi. Now it’s just a matter of getting a few more of these boards put together for the Best Product part of the Hackaday Prize.

 

The 2015 Hackaday Prize is sponsored by:

Simple One-Chip Regenerative Receiver

July 26, 2015 by 22 Comments

Crystal radios may be the simplest kind to make, but regenerative receivers are more practical and only a little more complicated. A recent design by [Selenium] is super simple because it uses a single LM386 audio amplifier IC.

You might be surprised that you can convert an audio amplifier to a receiver using just a handful of components (a variable capacitor, a coil, a handful of capacitors, and a speaker). However, [Selenium] realized he could subvert the gain and bypass pins to cause regeneration and wound up with a very simple receiver.

If you haven’t looked at regenerative receivers before, the principle is simple (and dates back to 1912). An oscillator is an amplifier that gets (theoretically) an infinite amount of gain at one particular frequency. A regenerative receiver is just an amplifier that is almost (but not quite) at the point of oscillation. This gives it very high frequency-specific gain and a measure of selectivity. You can also nudge the receiver just into oscillation to receive CW or SSB signals.

[Selenium] built his prototype on an old receiver chassis because it had the IC and the variable capacitor already in place. However, others have built successful copies on breadboards ([Austin Heller] created several good looking breadboard versions) and on PCB material. [Selenium] also released some other unique LM386-based designs that use more parts (and, probably, have better performance). Looks like a simple way to build a practical receiver.

Lithium Ion Upgraded Lawnmower

Upgraded LiPo Lawnmower Now Has Plenty Of Juice

July 26, 2015 by 21 Comments

Back in 2010, [Dave] took a stand. He gave up his dependence on gasoline for his lawn mower, and bought a CubCadet CC500 48V lead acid powered electric lawnmower. Within two years, the batteries had already kicked the bucket. Unwilling to let go, he replaced half of the batteries, but that wasn’t enough. It now took him two charging cycles to mow his lawn once

Enough was enough. He had to replace the whole set — but this time, with LiPo.

As an avid lover of drones, he’s been using LiPo batteries for other things for quite a while. He did some calculations and figured he would only need about 10,000mAh at 48V for a 40 minute run time, which would still be a pretty pricey upgrade. So instead he started with 2 x 22.2V 5,200mAh packs instead ($200). As it turned out, that was more than enough.

The circuitry in the CubCadet was pretty straight forward, so it was almost a drop in replacement, minus the need to use a different charger. He added in a switch to flip between charging and mowing modes to allow him to use the LiPo charger without damaging anything.

Now all he needs to do is give it an Internet connection or maybe make it remote-controlled…

Hacking Cheap Chinese PID Temperature Controllers

July 26, 2015 by 26 Comments

[Harvs] hacked a cheap PID controller he found on eBay to improve its performance. The controller originally used a K-type thermocouple but lacked cold junction compensation. As thermocouples only provide a differential measurement between the measurement junction and cold junction, this meant the controller was assuming the cold junction was at room temperature, and would in many cases be significantly inaccurate. The system also used a no-name brand Chinese microcontroller making firmware hacks impractical.

[Harvs] decided that even with cold junction compensation a K-type thermocouple wasn’t ideal for his application anyway, and designed a replacement PCB to interface to the display and power supply. The new PCB is based around a Cypress PsoC (a popular choice for its great analog functionality) with a DS18B20 temperature sensor. At the lower temperature ranges [Harvs] is interested in the DS18B20 is far more accurate and easy to use than the thermocouple.

Though the project hasn’t been updated recently, [Harvs] was planning on adding an ESP8266 for remote monitoring and control. Great work [Harvs]!

Thanks to Peter for the tip.