Heat your house with propane (but not in the way you’re thinking)

March 18, 2013 By 79 Comments

geothermal-heat-pump-charged-with-propane

[Ralph Doncaster] has a geothermal heat pump which is responsible for providing heat for his home. He’s been looking into some hacks that would make it more efficient and decided that the freon (R-22) needed to be tweaked. Some would say the stuff is bad for the environment, so he decided to go a different route. He replaced the Freon with propane, using this rig to make the fuel-grade propane more like cooling-grade propane called r-290.

He purchased the gauge set which is used whenever a technician services an A/C system (but you can also see it in this other A/C propane hack). That’s important because it’s responsible for making sure the old coolant is recaptured (his hose failure nixed this part of the plan) and the new coolant goes where it should at the correct pressure. But before dumping in propane from the local hardware store he needs to dry it out. Fuel-grade propane can have moisture in it, which can be bad for the cooling system. He bought a drier device, the grey bulb seen above, and soldered it on one end to a propane torch fitting and to a valve connection on the other. Now he could remove moisture as he pressurized the system.

Everything is working again, and the cooling side of the system gets much colder. He plans to do more testing as time goes by.

Filed Under: home hacks, repair hacks Tagged With: , , , , ,

Google Glass hack for Apple fanboys can be had right now

March 17, 2013 By 25 Comments

google-glass-for-apple-iphone

If you’re a follower of Apple hardware the upcoming Google Glass release probably doesn’t interest you much. But the concept is universally cool. If you want to have your own one-eyed voice-activated computer running iOS, then this is the hack for you. [John] calls it the Beady-i, and posted a step-by-step article on how he put it together.

The headpiece is shown on the left. It’s a combination of a pair of glasses with projection screens built-in, and a gaming headset. [John] cut off one of the lenses, and removed the remaining arm of the glasses. That arm was replaced with the frame of a gaming headset, which now wraps around the back of his neck to make sure the lopsided display isn’t going to fall off.

By combining the electronics from both the glasses and the headset, and terminating the connections with a docking plug he’s got what he was after. The lens displays what is shown on the screen, and the gaming headset lets him hear the device’s sound in one ear and register input using the microphone.

Filed Under: wearable hacks Tagged With: , , ,

Custom boards at home without etching

March 17, 2013 By 39 Comments

PCB

PC board houses are getting more accessable and less expensive all the time. Some of us are even getting very, very good at making our own circuit boards at home. There are times, though, when a project or prototype requires an extremely cheap custom board right now, something etching a custom board won’t allow. [KopfKopfKopfAffe] has a unique solution to this problem, able to create custom boards in under an hour without any nasty chemicals.

Instead of starting his build with copper-clad board, [KopfAffe] used every rapid prototyper’s friend, simple one-sided perf board. The shape of the board was milled out on a CNC machine, and both the top silk screen and bottom layer were marked off using the toner transfer method. After that, a custom circuit is just a matter of placing components and putting solder bridges between all the marked pads.

[KopfAffe] is only using this technique for single-sided boards, but we don’t see any reason why it couldn’t be employed for simple double-sided boards. This would still have the problem of making vias between the layers, but that’s still a problem with proper, home-etched double sided boards.

Filed Under: hardware Tagged With: , , ,

Auto off for any circuit

March 17, 2013 By 49 Comments

autooff

Properly configured, your computer will go into sleep mode when left unattended for a long enough time. So will your cell phone, and just about every other piece of sufficiently complex electronics. Much simpler circuits, though, are left at the mercy of a SPST switch; if you forget to turn a flashlight off, it will be dead next time you need to use it. Wanting an auto-off circuit simple electronics, [Kyle] threw together this auto shutoff circuit.

The basic idea behind the cirucuit is to use a microcontroller as a timer controlling two transistors. When [Kyle]‘s circuit is power cycled, the timer inside an AVR starts, making a pin high, and when the timer is up, making the pin low again. This pin feeds into a PNP transistor which is in turn connected to a NPN transistor, creating a very tiny auto off circuit for anything with an SPST switch.

[Kyle] says there are a few improvements to be made – using MOSFETS to handle higher currents and possibly using a smaller microntroller like an ATtiny 4/5/9/10 to shrink the circuit’s volume. It’s a great idea, bringing the idea of a flashlight with auto shutoff into reality.

Filed Under: hardware Tagged With: ,

Testing caps with a DIY ESR meter

March 16, 2013 By 14 Comments

ESR

There’s a problem with collecting old tube amps and vintage electronics – eventually the capacitors in these machines will die. It’s not an issue of a capacitor plague that causes new electronics to die after a few years; with time, just about every capacitor will dry out, rendering antique electronics defective. The solution to getting old gear up and running is replacing the capacitors, but how do you know which ones are good and which are bad? With [Paulo]‘s DIY ESR meter, of course.

An ideal capacitor has a zero equivalent series resistance, and failure of a capacitor can be seen as an increase in its ESR. Commercial ESR meters are relatively cheap, but [Paulo] was able to build one out of a 555 chip, a small transformer, and a few other miscellaneous components.

The entire circuit is built on stripboard, and if you’re lucky enough to find the right parts in your random parts bin, you should be able to build this ESR meter with components just laying around.

Filed Under: tool hacks Tagged With: , , ,

Sonic Screwdriver meets TV-B-Gone

March 16, 2013 By 34 Comments

sonic

[furrysalamander] has a friend that is a really big Doctor Who fan. It happens that this friend has a birthday coming up, and [furrysalamander] wanted to get her something amazing. A Sonic Screwdriver is always a great gift, but [furrysalamander] wanted to put his personal touch on it. He ended up adding a TV-B-Gone to [10]‘s screwdriver, turning a fictional deus ex machina into a functional device.

The body of the Sonic comes from this replica of [10]‘s screwdriver from Think Geek. Inside, the screwdriver has space for a battery a circuit board to control the lights and sound normally expected of a sonic screwdriver. [furrysalamander] added a freeform circuit composed of an ATtiny85, a transistor, LED, and a few resistors to add the ability to turn just about any TV off.

Of course [furrysalamander] needed to program the ATtiny with the TV-B-Gone firmware, and lacking any AVR development tools he used a Raspberry Pi’s GPIO pins to write the firmware to the microcontroller. That’s something we’ve seen before, but [furrysalamander] is a champ for including the process in his Instructable.

The end result is a Sonic Screwdriver that doesn’t work on wood and can’t break a deadlock seal. It turns off TVs just fine, though, and looks great to boot. You can check out a demo of [furrysalamander]‘s sonic in action after the break.

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Filed Under: toy hacks Tagged With: , ,

AC vs DC human pain test

March 16, 2013 By 62 Comments

AC-vs-DC-human-pain-test

Ever wondered just how much being zapped by electricity hurts? Curious if AC is worse than DC? Want to know just how many volts a human body can take? Although many people might cringe at the shear thought of it, [Mehdi Sadaghdar] is an electrical engineer who decided to turn himself into a human guinea pig and find out.

[Mehdi] measured the electrical resistance of his dry skin, his wet skin, and finally his tongue.  He found that his tongue had the least resistance, so it would feel the electricity at much lower levels. Using a bench power supply, he then used his tongue as a testing ground – slowly turning the voltage up and up until he could no longer take the pain. He tested the levels at which: he could first feel the electricity, when it began to get annoying, when it felt like torture, and when he could no longer stand the pain. He tried both AC and DC, and reports that AC is much worse.

Check out the informative, yet admittedly hilarious at times, video after the break. [Mehdi] seems like one awesome engineer! Remember – don’t try this at home.

[Read more...]

Filed Under: High Voltage Hacks Tagged With: , ,
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