Afroman Demonstrates Boost Converters

boosIf you need to regulate your power input down to a reasonable voltage for a project, you reach for a switching regulator, or failing that, an inefficient linear regulator. What if you need to boost the voltage inside a project? It’s boost converter time, and Afrotechmods is here to show you how they work.

In its simplest form, a boost converter can be built from only an inductor, a diode, a capacitor, and a transistor. By switching the transistor on and off with varying duty cycles, energy is stored in the inductor, and then sent straight to the capacitor. Calculating the values for the duty cycle, frequency, inductor, and the other various parts of a boost converter means a whole bunch of math, but following the recommended layout in the datasheets for boost and switching converters is generally good enough.

boostconverter

[Afroman]‘s example circuit for this tutorial is a simple boost converter built around an LT1370 switching regulator. In addition to that there’s also a small regulator, diode, a few big caps and resistors, and a pot for the feedback pin. This is all you need to build a simple boost converter, and the pot tied to the feedback pin varies the duty cycle of the regulator, changing the output voltage.

It’s an extremely efficient way to boost voltage, measured by [Afroman] at over 80%. It’s also exceptionally easy to build, with just a handful of parts soldered directly onto a piece of perfboard.

Video below.

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Monster 100W LED Flashlight Produces a Whopping 8500lm!

100W LED Flashlight

[Yannick] got a hold of a 100W LED diode recently, and like any self-respecting hacker, he just had to turn it into a ridiculously over powered flash light.

The tricky thing about these diodes is that they need a high amount of DC voltage, anywhere from 32-48V typically. [Yannick's] using a 12V sealed lead acid battery coupled with a 600W constant current boost converter which ups it to 32V at around 3.2A. He also managed to find a giant aluminum heat-sink to keep the diode from getting too hot. A 120mm fan helps to keep the heat sink nice and cool, which allows the light to be run constantly without fear of burning it out. But just in case he also has an Arduino monitoring the temperatures — oh and it provides PWM control to adjust the brightness of the light!

To focus the flashlight he bought a proper lens and reflector which can be mounted directly to the diode. At full power the LED puts out around 8500lm, which is brighter than almost all consumer projectors available — or even the high beams of a car!

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Accelerometer Poi

accelerometerPoi

Even if you’ve never attended a rave, you have probably seen one portrayed on film or television. Those glowing spheres-on-a-string being swung around are called poi, and [Matt Keeter] has designed a pair with an accelerometer upgrade. Poi have a long history and were originally made from plants, but contemporary examples usually feature some kind of light, whether it’s fire, LEDs, or even glowsticks tied to shoelaces.

This build required double-sided PCBs and [Matt] had to custom make the protective covering that slips over the board. The poi are powered by 2 AA batteries fed into a 5V boost regulator. But wait, no microcontroller and no PWM? Actually, we think it’s quite clever that [Matt] took the output from the accelerometer and fed into an inverting amplifier. This keeps the voltage constant while allowing the accelerometer to vary the current. Had he used PWM, the fast motion of the swinging poi would instead produce a blinking effect.

An additional trimmer potentiometer accounts for variability in the accelerometers’ output by adjusting the default brightness. If the recent recap of Burning Man has you excitedly planning to attend next summer, you’d probably find plenty of opportunities to use these in the desert.

USB fume extractor takes stink out of soldering sessions

usb-powered-fume-extractor

Our homemade shop tools rarely reach this level of finished quality. We probably would have stopped with assembly of this USB powered fume extractor. But [X2jiggy] went for style points by adding a coat of paint.

There are several nice features included in his build. He wanted it to be very easy to power the device so he settled on the 5V USB standard. But a PC fan running at 5V won’t pull much air. He used a boost converter board to ramp that up to 12V. The enclosure is a wooden hobby box. He drilled mounting holes and an airflow opening in the bottom of the box for the fan. The lid of the box has a rectangular opening which accepts a carbon filter meant for aquariums. The rocker switch and LED seen above are also nice touches, but not strictly necessary if you build this for yourself.

We’re still in the habit of gently blowing the fumes away from us as we solder. So the question is, will this device save us from a gruesome disease down the road, or is it mostly to capture the odor of the solder fumes?

Looking for a more permanent setup? You should build a solder hood for your workbench.

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Building a bipolar supply from a boost converter

This DC-DC Bipolar PSU was developed for use with a guitar effects pedal. [Obsolete Technology] needed to source both positive and negative 15V. This is pretty easy to do if you’re converting from mains, but he wanted a solution that could work with a lower-voltage AC/DC wall wort or even from batteries.

The part that pulls it all together is the LT3467. It’s a switching power regulator which offers a range of features configured by the layout of a handful of external passive components. It can put out 80 mA on each line (positive and negative). Also extremely useful for this application is the chip’s high frequency operation. Depending on the version, it switches at 1.3 or 2.1 MHz. This is high enough that it will not introduce audible noise into the audio system.

We’ve got an exercise bike whose negative supply for the LCD is blown. We’re going to try build this circuit, trimming it for our voltage needs, and get the contrast working again.

[Thanks Olli]

Nixie Clock Without a PCB

Looking for an artistic way to build circuits? Don’t want to design a PCB? The Lethal Nixie Tube Clock is a free form circuit that gives you the time one digit at a time. It uses a IN-1 Nixie tube to display the digits. This is driven by ten MPSA42 high voltage transistors. A IRF520 N-FET, inductor, and a diode are used as a switching power supply that generates the high voltage needed to drive the Nixie tube. It’s probably not lethal, but there are exposed high voltages in the cube. You’d definitely regret touching it.

An ATMega8 is used to control the clock. It drives the various digits of the Nixie tube, and generates a PWM output to switch the high voltage supply. Unfortunately, the schematic has been lost. If you’re interested in the switching supply, it’s likely similar to the one explained here.

Check out a video of the clock after the break.

Via Dangerous Prototypes

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RC car upgraded to Bluetooth control

[Chet] is showing off the Bluetooth controller upgrade for this RC car. The donor vehicle is a rather inexpensive Porche which he purchased to make sure he didn’t start hacking up his more expensive toys.

He took a bit different route than the IOIO RC truck we saw earlier in the week, but the concept is basically the same. That build used an IOIO board with a USB Bluetooth dongle. This one uses an Arduino Mini with a serial Bluetooth module. He patched into the motor driver circuits on the original PCB. While he was at it he also soldered in some LEDs to use as switchable headlights.

There was one issue which he had to overcome. The current draw from the motor starting up would sometimes dip the voltage low enough to reset the Arduino. He tried using a bigger capacitor to feed the board, but in the end opted to add a boost converter.

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