Preparing a ventilated protective mask for Airsoft

Homemade ventilation mask

Eye protection is mandatory in airsoft, but most masks do not have enough ventilation, so you end up with very low vision by condensation on the policarbonate plastic.

As others have done before me, the trick is to introduce fresh air with a small fan and battery; I used a fan from a notebook computer, with a small switch and a 18650 lithium battery (4.2V) in the corresponding adapter .

Repairing an old Mitutoyo profilometer probe

Some time ago I repaired an old Mitutoyo profilometer 178-928D , which no longer has spares and which had broken the pin that transmits motion to the head holder; a calibrated shaft that moves left and right and which I hold in the following image (the pin / screw was in the center hole):

This probe has a very simple operation. The spindle that is coupled detects changes in a very similar way that is translated the marks in an old LP music disk, transmiting the movements caused by the roughness by a magnet and coil needle.

The shaft that moves the spindle is moved in a controlled manner with a step by step motor to an endless spindle, first the engine slowly forward in the measurement phase, and then quickly picking head to its starting position, all controlled from the profilometer which is connected with a cable with 6 wires (that is a seven or eight cable, but one or two are not used, as you can see in the following images after repairing the cable too):

Repairing a tape backup LTO 2 unit: HP Ultrium 448 with broken tape

In a unit Ultrium Fujitsu (HP) for backup, the tape had broken, being useless as the mechanism for capturing the tape was inside it. To repair the unit is complicated, recommended only to those who have already dealt above with similar mechanisms (VHS, glory times). 
To repair it is necessary to understand the method these units use (and many other models are based on the same principle), a curious way to save space by having a single drum in the cartridge and in the unit, where the tape passes from one side to another as information is stored, until it ends.

These LTO (Linear Tape Open) are optimized for capacity, and the latest versions, able to store 2.5TB of information in one cartridge that costs about 20 €, making it very competitive in terms of price and space currently.

After this brief introduction, let's go to the subject.

6 tips to save on your vehicle maintenance

Today, thanks to the internet we have plenty of advices and hints to save maintaining our vehicle, we have plenty of tutorials for whom are a little handyman; from changing lamps, brushes, etc to oil changes, and some dare to change pads and cushions. After years of use with my Xsara Picasso, I share with you the ideas and optimizations that can be applied to your vehicle to save money, helping the nature too.

1. Change the rubber instead of the entire windshield wiper

Change only the rubber and be ecofriendly

Repairing and Adflo Speedglas battery ref 837621 with LI-ION 4.2V Cells

Lately I have been repairing multiple wireless devices whose NI-MH batteries have deteriorated ; usually get considerably cheaper make you the battery pack with a new charger is to buy it new; in this tutorial I will show how to build a battery of 4500 mAh 12.6V and 3 packs of 3 cell li-ion parallel each to replace a battery 10.8V and 4000 mAh NI-MH (9 batteries in series 1.2V) with just 32 € (charger not included).

Update: I uploaded how I repair them to youtube:

HD version

And slim version.

LITHIUM battery types depending on their composition

The Lithium-ION technology has improved a lot as  the advantages of having no memory effect and higher energy density per kilogram than any other current technology , we can add that  depending on the type of materials used , allows different power / energy densities; we can have instantaneous powers from 1C (2A / time to a cell 2000 mAh) of the LI-Cobalt portable typical 5C of manganese (LiNiMnCoO2) or 15C for the past employed in Automobiles (LiNiCoAlO2) or 30C with LiFePO4 .

Modifying an airsoft HK 416 UMAREX with 11,1V for increased rate of fire: from 13 bps to 18 bps

HK 416 from UMAREX, very high quality materials and precision

Recently I personalized with more cadence one airsoft replica HK 416 from UMAREX, the best available today replica of the lethal original, getting to shoot 18 balls per second instead of 13 with the recommended battery.

For this we have got 11,1V instead of the 7.4V li-ion recommended by the manufacturer, using 6 standard size batteries 2000 mAh 18650 and 1C discharge . Usually LiPo is more desirable for these cases, for the effort that must hold the batteries, they probably will last less than normal ... but what can we do... life is short;) and we just had them available.

Putting 11,1V to the repeater you are breaking the guarantee, but it have such good material and design that we'd rather risk getting a machine of epic massacres;)

In the following video a Youtube friend did the same and is working very well:

How works an electric cooler: Cell peltier

We pack a cooler for the curious

Well, after a temporadilla almost no entries, I think this summer will not you going to complain;.)We'll start with this entry, in which he disarmed a cooler of those that plug into the car (or home if you adapt one transformer least 5 amps and 12 volts), to discover another fascinating use of semiconductors (thermoelectric effect) and electricity: The Peltier cells .

Replace magnesium sacrifice anode in hot water tank by yourself

After four years working properly, it is time to do the maintenance of DHW storage tank from the solar thermal collector  changing the magnesium anode which prevents the deposition of oxide by galvanic protection .

Sacrificial anodes will last more or less depending on tank size and the degree of degradation thereof , that is; if you have many areas without paint, he's paid to oxidation and anode (magnesium in this case) will provide more ions, degrading its structure more quickly.

First of all, we acquired a couple of sacrificial anodes, are cheap, about 15 € each (I ordered them on Ebay for a company of Madrid). To change it, release the cover ( IMPORTANT empty it first ), loosen all the lime and use mud accumulated over the years:

Repair of electronic tracks on an old keyboard: Conductive silver liquid

In this post we will repair CNC keyboard that is no longer being manufactured

Contacts on the keyboards have evolved from mechanical systems to more modern with membrane. In this case we will repair an intermediate type; this keyboard from a Gemini 8050T FAGOR around 15 years old carries a screen printed aluminum membrane for tracks and graphite contacts, on which a metal piece with flexible concave shape closes the contact when pressed.

The technology of switches on keyboards usually are of two types: contact , where some kind of spring (metal or plastic or flexible rubber, etc) keeps separate tracks of the conductive surface (graphite or other) of the button, which when pressed blend tracks; and secondly, the induction, where pressing the button, a small magnet creates a small electrical pulse in the coil of the membrane (ultra durable modern musical keyboards).

Repairing first type of keyboards often requires all your ability of "handyman"; some with copper tracks like TV remotes are often easier to repair welding on the tracks a small micro-switch if the button is completely useless, but most cases are plastic membranes that can not be welded and we can use either glue threads on them as in this entry, or use the useful liquid silver, and you will always get a more professional work to build the appropriate cable connections.

Equipment needed

1. Cutter to open the damaged contact (in other keyboards will not be necessary).
2. Cleaning liquid or solvent which does not attack the material of the keyboard; I used Ardrox 9PR5 or you could use isopropyl alcohol.
3. Liquid silver conductive, with which "will draw" deleted / damaged tracks with a fine brush after cleaning them well.
4. A tester to verify that the track drawn conducts electricity.
5. Scissors, PVC tape to cover the contact again, brush, permanent marker to draw the button again, etc.

Get the most out of your SSD: Adjust Windows 7 settings

I chose the 840 Evo 250GB for its value / capacity / price

Change your computer's hard drive for an SSD ( Solid State Drive ) is the best way to rejuvenate a few years , letting you skip loading the operating system in a minute to do it in just 15 seconds ; thanks to the speed of read / write access to the programs is almost instantaneous.

Disks SSD, being immune to shock and vibration , are especially recommended for laptops, as discussed in the previous post on the subject . The best value are the Samsung and Crucial (for less than 100 € 250GB -4/06/14).

And if you use the Samsung RAPID software, get these speeds ( Source )