# Retrotechtacular: DC to DC Conversion, Rotary Style

If you want to convert one voltage to another, what do you do? Well, if you are talking DC voltages today, you’ll probably use a DC to DC converter. Really, these converters generate some sort of AC waveform and then use either an inductor or a transformer to boost or buck the voltage as desired. Then they’ll convert it back to DC. If you are talking AC voltages, you could just use a transformer. But think about this: a transformer has two sides. The primary makes an alternating magnetic field. Just like rotating a shaft with magnets on it could. The secondary converts that alternating magnetic field into electricity just like a generator does. In other words, a transformer is just a generator that takes an AC input instead of a rotating mechanical input.

That’s a bit of an oversimplification, but in the old days, a lot of mobile radios (and other devices) took this idea to its logical conclusion. A M-G (Motor Generator) set was little more than a motor connected to a generator. The motor might take, say, 12V DC and the output could be, for example 300V AC that would get rectified for the plate voltage in a tube radio.

# Retrotechtacular: DC to DC Conversion by Vibrator

Electricity comes in two basic forms: Alternating Current (AC) and Direct Current (DC). DC is handy to use and is easy to analyze. However, AC has some useful properties too. In particular, AC current can operate a transformer which can step it up or down easily. Power is conserved, of course (well, actually, you get less power because of losses in the transformer).

You can’t do that trick with pure DC. You can reduce a voltage, although that typically wastes power in heat (for example, a voltage divider or linear regulator). You can’t readily increase a DC voltage unless you convert it into some sort of AC first.

This was a particularly bad problem in the era of tubes–especially tubes in car radios. The car’s voltage was probably 12V but the tube’s plates might take hundreds of volts. What do you do? Some old car radios used what is called a dynamotor. This is just a motor and a generator in one box. You could spin the motor with 12V and have the generator produce a different voltage (even a DC voltage).

# Making a touchless vibrator with reverse engineering

Here’s one for the ladies (and men, we guess) out there.

[Beth] recently bought a LELO Lyla vibrator for herself, but found operating this wireless vibrator to be an exercise in mood-killing awkwardness. Wanting a more natural interface, she decided to reverse engineer a remote control vibrator. Here’s a cache; [Beth]’s blog has been up and down all day.

The LELO Lyla comes with a wireless control in the form of a neon pink remote. [Beth] thought this remote was a little clunky and felt like programming a VCR – something she doesn’t like in a sex toy. With the goal of improving this remote and allowing for a better user experience, [Beth] tore down this remote and began to build her own.

The new vibrator remote would have to be touchless – there’s nothing that kills the mood faster than mashing buttons. By using ultrasonic sensors, [Beth] would be able to control the intensity of her vibrator by simply waving her hand; a much more natural interface. With the control interface out of the way, the only thing left to do was to figure out how to control the business end of the vibrator.

The remote for a stock LELO Lyla comes with a MSP430 microcontroller and a 2.4 GHz CC2500 radio controlled over an SPI interface. Instead of disassembling the microcontroller and figuring out the firmware from scratch, [Beth] decided to sniff the SPI bus and make her own controller.

After attaching some 0.1″ headers to the stock remote and soldering a few wires to the microcontroller, [Beth] captured the SPI data with a Propeller dev board. By streaming the SPI traffic to a terminal, she was able to figure out exactly how the remote works and set out on building her own.

The new remote was built out of an Arduino Pro Mini, ultrasonic sensor, CC2500 radio and a four digit 7-segment display. After printing an enclosure, [Beth] had a very easy to use, hands free vibrator.

In the video after the break you can see [Beth]’s vibrator in action. She’s still looking for a few more ways to improve it such as predicting the movements of her hand with a phase-locked loop, but for now we’ll just tip our hat to [Beth] for a very awesome hack.

# Urban Defender: location aware game

What do gangs, territories, cities, and glowing blue balls have in common? No, not that one drunken night you can’t seem to remember, rather a new location aware game called Urban Defender.

The concept behind the game is simple. A player hold a ball that knows its current location and can notify you if needed via LEDs and a speaker of changes in its environment. He or she then runs around the city until the ball tells them of an unclaimed or enemy territory. Bounce the ball against a building and that territory is now claimed.

The ball itself is a prototype combination of an Arduino, Accelerometer, vibration motor, LEDs, XBee, batteries, and wire all packed inside of an industrial rubber gym ball. Unfortunately after testing the Urban Defender team found the GPS and a few other components would need to be kept outside of the ball and on the player.

Finally, a project that warrants the use of an Arduino. Anyone up for a game?

# Steampunk vibrator

[Ani Niow] built this steam powered vibrator. It has a milled stainless steel shell with a brass motor structure. The motor is a Tesla turbine made from a stack of Dremel diamond cutoff wheels. This drives an off-center weight to create the vibration. She tested it using a pressure cooker as the steam source. It worked, but became so hot it had to be held using welding gloves. It works just as well with compressed air though. You can see the device at the Femina Potens Art Gallery in San Francisco or later this month at Maker Faire.

[via Laughing Squid]

UPDATE: [Ani] responds in the comments.

# Haptic compass

[eric], inspired by this Wired article, built his own haptic compass. Named “the clown belt”, it is a belt with 12 little vibrating motors mounted evenly all around. A digital compass vibrates whichever motor is closest to north at all times. This basically gives the owner an extra sense.  He doesn’t go much into his own experiences, but the Wired article mentions “dreaming in north” and feeling strange once they finally removed it. Precise direction senses may not be super power worthy, but they would be cool.

[thanks cnelson]

# Wearable haptic devices bestow sixth senses

Engadget recently posted a story about a flexible tactile display that can be wrapped around any part of the body and give haptic feedback to the user. The research team from Korea’s Sungkyunkwan University that developed the device are focusing on applications like Braille for the visually impaired or transmitting tactile data to a remote user, but this is just the beginning; the applications for wearable haptic feedback are wide open.