18-Channel PWM Aquarium Lights Provide Habitat-Like Life for Fish

Aquarium with variable LEDs

Whether you want to keep your fish happy or just need a good light show, this aquarium light fits the bill. It is the second iteration, but [William] calls it v1. That’s because v0 — which used a few loops of LED strips — never really met his requirements.

This build uses just six LEDs, each a 30 Watt RGB monster! To source about 350 mA for each, and to control brightness with 18-channels of pulse width modulation, he had to plan very carefully. This meant a proper aluminum project box and a beefy, fan-cooled power supply.

The driver board is his own design, and he etched a huge board to hold all of the components. Everything is driven by an Arduino Mega, which has 16 hardware PWM channels; two short of what he needed. Because of this he had to spend a bit of time figuring out how best to bit-bang the signals. But he’s putting them to good use, with fish-pleasing modes like “sunset” or the “passing rainbow” pattern which is shown in the image above.

If you need something a little less traditional why not house your fish in a computer case, complete with LED marquee for displaying data.

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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A Most Impractical Gear Position Indicator

GPI A few years ago, [Pat] sent in a really nice gear position indicator for his Suzuki V-Strom. With a single seven-segment display , a small microcontorller, and wires tied right into the bike’s ECM, it’s more than enough to do its job, and is much cheaper than aftermarket gear indicators. A simple, elegant solution that does one job well. How could this possibly be any better?

‘Better’ is a relative term, and depending on what you’re optimizing for, a more complex solution can easily be superior. [Pat] figured tripling the value of his motorcycle is a worthwhile goal, so he replaced that seven-segment display with an oscilloscope. It’s the world’s only oscilloscope based motorcycle gear position indicator, and now [Pat] needs a really, really long extension cord.

Like the earlier, more practical version, This build reads the voltage off the bike’s ECM to determine what gear the bike is in. The current gear is then displayed on a Tek MDO3000 with two PWM pins on a microcontroller. Practical? No, but it does look cool. Video below.

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Attiny PWM Generator and Servo Tester

PWM-Servo-Tester

Having the right tool for the job makes all the difference, especially for the types of projects we feature here at Hackaday. [Jan_Henrik's] must agree with this sentiment, one of his latest projects involves building a tool to generate a PWM signal and test servos using an Attiny25/45/85.

Tools come in all kinds of different shapes and sizes. Even if it might not be as widely used as [Jan_Henrik's] earlier work that combines an oscilloscope and signal generator, having a tool that you can rely upon to test servos and generate a PWM can be very useful. This well written Instructable provides all the details you need to build your own, including the schematic and the necessary code (available on GitHub). The final PWM generator looks great. For simple projects, sometimes a protoboard is all you need. It would be very cool to see a custom PCB made for this project in the future.

What tools have you build recently? Indeed, there is a tool for every problem. Think outside the (tool) box and let us know what you have made!

The Un-Digital Robotic Arm

556When you think of a robotic arm, you’re probably thinking about digital control, microcontrollers, motor drivers, and possibly a feedback loop. Anyone who was lucky enough to have an Armatron knows this isn’t the case, but you’d still be surprised at how minimal a robotic arm can be.

[viswesh713] built a servo-powered robotic arm without a microcontroller, and with some interpretations, no digital control at all. Servos are controlled by PWM signals, with a 1 ms pulse rotating the shaft one way and a 2 ms pulse rotating the shaft the other way. What’s a cheap, popular chip that can easily be configured as a timer? Yep, the venerable 555.

The robotic arm is actually configured more like a Waldo with a master slave configuration. [viswesh] built a second arm with pots at the hinges, with the resistance of the pots controlling the signal output from a 556 dual timer chip. It’s extremely clever, at least until you realize this is how very early robotic actuators were controlled. Still, an impressive display of what can be done with a simple 555. Videos below.

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An “ill” logical PWM control

illogicalPWMcontrol

[James] recently finished up a gigantic seven segment display for Nottingham Hackerspace, and although it looks great, the display isn’t the interesting part. The PWM dimmer control implemented in logic is the true head-turner. That’s right: this is done without a programmable controller.

Unsatisfied with the lack of difficulty he faced when slapping together the rest of the electronics, [James] was determined to complicate the auto-dimmer by foregoing all sensible routes. He started by building an 8-bit timer made from a 555 timer fed into a 12-bit 4040 counter. He then used an 8-bit ADC IC to read a photoresistor. The outputs from both the ADC and from the scratch-built 8-bit timer plug into an 8-bit comparator; If the values match, the comparator outputs LOW for a single clock period.

Though this set the groundwork for PWM control, [James] had to add a couple of additional logic gates into the mix to nail everything down. You can find a diagram and the details behind flip-flopping out a duty cycle on his project blog. Clever builds like this one are a rarity when a few lines of code and a microcontroller can give you numerous shortcuts. [James] doesn’t recommend that you over-engineer your PWM controller, but we’re glad he did.  Meanwhile, Moore’s Law marches on; check out what people are doing with Low-Energy Bluetooth these days.

The easy or hard way to build a PWM dimmer

555

From what you would gather from Hackaday’s immense library of builds and projects over several years, the only way to do PWM is with a microcontroller, some code, a full-blown IDE, or even a real-time operating system. To some readers, we’re sure, this comes naturally and with an awesome toolchain it can be as easy as screwing in a light bulb. There is, of course, an easier way.

[Jestin] needed to vary the current on a small 12 Volt load. Instead of digging out an in system programmer, he turned to the classic 555 chip. With a single pot, it’s easy to vary the duty cycle of the 555 and connect that to a MOSFET. Put a load in there, and you have a very easy circuit that’s a fully functioning PWM dimmer.

If all you have are a few scraps in your part drawers, this is a very, very easy way to set up a dimmer switch. We’re also loving [Jestin]‘s improv aluminum tube enclosure, as seen in the video below.

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