Mixed I/O testing module

Needing to test the display interface for a multitude of different sensors [Fileark] built himself this analog and digital input/output simulator. Along the bottom is a double row of trimpots that adjust analog voltages. Each voltage is measured by the Arduino inside and its value is displayed on the graphic LCD screen to confirm that the hardware you’re testing is making correct measurements. There’s also digital I/O in two different forms. To the upper left are momentary push buttons but the DIP switch bank below that allows the same connections to be toggled on and off. It’s not an automated test bed, but if you’ve got a lot of I/O, or a lot of hardware to test this will save you some real time.

Don’t miss the demonstration video after the break.

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Analog computer does math

This analog computer can multiply, divide, square numbers, and find square roots. It has a maximum result of ten billion with an average precision of 2-3%. [Miroslav’s] build recreates something he saw in a Popular Electronics magazine. It uses a resistor network made up of three potentiometers with a digital multimeter is an integral part of the machine. To multiply a number you set the needles on the first two knobs to the numbers on which you are operating. To find the result turn the third knob until the multimeter has been zeroed out and read the value that knob is pointing to. It seems much more simple than some of the discrete logic computers we’ve seen, yet it’s just as interesting.

Web controlled watering can

Here’s a watering can and water vortex that are controlled with a webkit browser interface. The interface displays a drawing of the watering can on your browser. If you grab one of the handles on the circle around the image and move it, the can will rotate as well.

Okay, so this isn’t going to change the world and actually presents a fairly useless watering setup. But [Ben] seems to be a master of fabrication and that’s what we appreciate in this build. The watering can is solidly mounted and moves fluidly with seemingly little effort from the motor. He uses a spring to keep the rope loop taut, sourcing a castor wheel and automotive power-window motor to provide the motion. The hinged base on which the can sits has a potentiometer in it, used to measure the current position of the watering can. Remember these techniques as they’ll come in handy in your future builds.

There’s also a little bonus at the end of the video after the break. We wondered what [Ben] might use that power drill controller hack for. Looks like it makes an appearance in his water vortex work.

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Easy data input for LabVIEW

Props go to [Michael Nash] for establishing an interface between National Instrument’s labVIEW and an Arduino (an example video using a potentiometer is above). Personally, from the one time we were forced to use labVIEW, we hated every second of it.

One reason it’s so terrible, is the Data Acquisition Modules cost well into the hundreds of dollars, yet the documentation and help resources are very scarce. By using an Arduino instead of the modules, the price and difficulty decrease a considerable amount. Which begs the question why has it taken so long to get a decent (and so simple) of a setup working?

Hacking Game Boy for sound

[Gijs] cracked open his Game Boy and added some parts to give him more sound synthesis control. He uses Little Sound Dj (LSDj), a popular Game Boy program used to pump out those classic 8-bit sounds. The unit seen above and heard in the clip after the break has an added potentiometer and circuit board. He’s got a few other hacked Game Boys on his site as well, including an Arduino generating random music on the handheld.

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Multiple buttons and a pot on one pin

[Kevin Fodor] shares his method of reading multiple inputs on one pin of a microcontroller. The analog to digital convert function of the microcontroller is used to read a potentiometer but with some careful calculations a resistor network can be built into the circuit that provides a unique voltage value for each button pushed. The only real drawback is that the system cannot read multiple button presses at the same time. Theoretically up to ten momentary push buttons can be used but [Kevin] estimates that only four plus the potentiometer will work reliably.

[Thanks Charper]

Two input devices made with common items

Here’s two input devices you can easily build with materials you already have on hand.

To the left, [John] built a 3×3 keypad matrix from paper and tinfoil. The rows and columns are made up of strips of tin foil on the front and back layers of paper. The layers are separated by spongy double-stick tape. A ‘keypress’ results when the gap between the conductors is compressed with your finger.

In much the same way, [Dave Fletcher] built a touch potentiometer. He made two resistance plates by scribbling pencil lead on sheets of paper. When the two plates face each other, separated by the same type of foam tape as before, they can be pressed together to form a circuit with a variable resistance. This results in a crude version of the SparkFun softpot.