Blinky headgear

This hat has a chasing LED feature thanks to our old friend the 555 timer. [BananaSlug] even built in the option to change the speed at the push of a button.

His design starts out with a costume hat. Each of the 25 LEDs is soldered to a 2×4 hole chunk of protoboard. The LED package is pushed through a slit in the hat, but the protoboard remains on the inside where it can be sewn in place. From there [BananaSlug] soldered one negative bus around the circumference, and an individual positive lead from each module back to the control board. They’re addressed by a set of CD4017 decade counters which are clocked by the 555 timer circuit.

This is a great little analog/logic project and the style is perfect if you’ve got the coat to go along with it.

Remove Function Lock Key with a 4016 and a 555

Many companies today try to simplify life by over complicating the keyboard. Microsoft has been doing it since 2001. If you love your ergonomic keyboard, but hate that “function lock” key, there are plenty of options out there for you to try.

The least complicated way is to either modify some XML or just set macros up in the MS software, but who wants to do that every time they re-install Windows? Reader [Elco] didn’t so he added a simple little 555 circuit inside the keyboard, that automatically re-enables the Flock after three seconds if he happens to hit it during fast and furious typing.

Now no matter what system the keyboard is plugged into he does not have to worry that if he hits F7 whether the system is going to spell check his document, or reply to an email, or that F2 is actually going to rename something and not undo his work silently.

Light up your workshop with this arcade button light switch

arcade_button_light_switch

[Pete Mills] was browsing around online when he came across an arcade button light switch and immediately wanted one. He didn’t however want to pay the $35 asking price for the switch, so he decided to build it himself.

He says that his solitary arcade machine doesn’t warrant its own room, so he figured he would wire the switch up to an extension cord in his workshop instead. The switch was made with parts he had on hand, so seeing as he didn’t have any triacs, he opted to use a relay in its place. He thought about how he would construct a simple flip flop circuit for the switch, and settled on using a simple 555-based circuit instead of a pair of transistors.

The end result looks every bit as nice as the version available for sale online, and it works great as you can see in the video below. [Pete] has circuit schematics available on his site should you want to build your own, so if you do, let us know in the comments – we’d love to see different variations on the circuit design.

[Read more...]

The Dish-o-Tron 6000 is back and better than ever

dish_o_tron_6000_extreme

When designing a circuit on the bench, sometimes things work far better than they do in real life. [Quinn Dunki] learned this lesson over the last few months as she struggled with one of her recent creations, the Dish-o-Tron 6000. We featured the Dish-o-Tron back in April, and at that point things seemed to be working out well for [Quinn]. As time passed however, she found the device to be an unreliable power hog. Aside from eating through a battery every few weeks, it kept spontaneously switching states from ‘Dirty’ to ‘Clean’ and back. It was time to take the Dish-o-Tron back to the bench for some debugging.

The random status flip from ‘Dirty’ to ‘Clean’ was a relatively easy fix, and required a small capacitor between the set pin and ground to eliminate the electrical noise that was tripping things up. She nailed down the spontaneous ‘Clean’ to ‘Dirty’ flip to a stuck tilt switch, which she swapped out for a mercury-based model, making things far more reliable. She solved her battery problems by wiring in a 12v wall wart, which might not be any more energy efficient, but it does save her from swapping out batteries all the time.

It’s always nice to see how projects evolve over time, and how the inevitable bugs are worked out of an initial design.

High Voltage: Using enclosed relays for HV switching


After seeing many projects that use microcontrollers to switch mains voltages [Rob Miles] decided to share his preferred method. The shots you see above are an enclosed relay, part number RIBTU1C manufactured by Functional Devices Inc.

This in itself is not the full control scheme that he uses, but it takes care of the bulk of the hardware. He uses a triggering circuit based on a 555 timer (PDF). [Rob] mentioned that if you shop around, you can get the relay, 555 timer, and other components for under $15. This is a great solution for the money when you consider that you get an enclosure meant for handling high voltage and a nice terminal block to which you can connect the mains wiring. The relay itself can be triggered by a 9V battery via the transistor in the control circuit.

Notice the protoboard in the image above. There’s plenty of room for your driver circuit to rest inside the box, protected by that barrier from the HV circuitry. Check out the rest of the images he sent us after the break.

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Minimalistic 555 Adding Machine

How many 555 timers does it take to add up two 10 digit numbers? [Alan's] 555 Adding Machine does it with 102 of them, he designed the machine as an extreme entry to the 555 contest and the original plan was to make it even more complicated. This machine uses the 555’s to implement a nine decade accumulator and multiplexer, all inputs are managed by an old school dial from a rotary phone which apparently provide nicely timed outputs. Addition and subtraction are achieved using 9s compliment arithmetic which he discusses in the video after the break, for anyone who wants to brush up on 9s compliment or 555 theory.

Alan’s website has some nice pictures (We’re particularly impressed by all that minimalistic soldering) including schematics, and a very nice 33 minute video in which he discusses in detail how the machine works and even offers some history on the Pascaline, which is mechanical calculator that works on similar principles.

[Read more...]

Dishwasher notifier for the absent-minded

dish_o_tron_6000

[Quinn] over at BlondiHacks is admittedly pretty absent-minded when it comes to household chores such as emptying the dishwasher. She often can’t remember if the dishes are dirty or ready to be put away, so she decided it was time to devise a mechanism that would help keep her on task. She originally considered a double-sided sign that said “Clean” on one side, “Dirty” on the other, but she chose the fun option and decided to over-engineer the problem instead.

She ultimately focused on two conditions that she needed to monitor: when the dishwasher had been run, and when the dishes have been emptied. To tackle the first condition, she used a thermistor to detect when the door of the dishwasher got hot from the wash cycle. The second wasn’t quite as easy, since she often peeks into the dishwasher to grab a clean dish when needed, unloading the rest later. She eventually settled on using a tilt switch to monitor the angle of the door, assuming that the dishes have been removed if the door was open for over a minute.

[Quinn] reports that her Dish-o-Tron 6000 works well, and she had a good time building it. Sure the whole thing is kind of overkill, but where’s the fun in moderation?

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