Construct your own DC Power Supply Wall Wart! Variator Reporting.

Alhamdulillah. All Praises to Allah SWT who created and governed everything in this world.

So guys.. we'll be doing something very important for hobbyists here. All electronic circuits require a steady power supply, and you'll get fed up using batteries for testing purposes, which run out of juice for only an hour's worth of running time.. That excludes the electrolytes which leak out after some time.. (NOOOO!!!).....

So.. normally people would opt to: Buy a costly DC wall wart, with fancy controls and an indicator (which is sometimes deceiving) and risk thinning your wallets......

.....or construct their own by buying cheap DC supplies and hacking it to suit their applications. In my experience, after some time the cheap DC supply will be overheated and you'll be left with a fuselage of burnt plastic and a dead transformer.

....or you can opt to take a leaf out of the book of Vortex Electrica and use your own adapters in your house. There are tons of adapters for various applications; Laptop chargers, printer adapters, cellphone chargers (especially old ones), and so on. What's the difference between the ones you buy? Normally adapters for branded stuff have more quality and more protection circuitry. So... This is my collection:

A lot huh? Some of 'em are damaged, and some are okay. Each can be tested easily using an LED and a 100 ohm resistor.

So... the obvious steps for anyone with basics is to cut the wires loose and connect crocodile clippers to them, right?

WRONG! From experience, the weak points are always attributed to the connection between the wire and clip, because the CLIPS SUFFERS THE MOST MECHANICAL STRESS HERE, SO THEY BREAK APART EASILY AFTER SOME TIME. So if you don't want to have to repeatedly re-solder the clips to the wires, the best thing to do is to make separate connections, which can be plugged when in use. In short, see below:

So.. the figure should give an idea. Also, this means that the power from the DC adapter can be plugged into other circuits i.e not only the crocodile clips but also to a breadboard, or any other devices which have the corresponding socket to fit.

Now, another series of ideas comes into play: I want to have.....

a. indicators to know that it is ON, and

b. I want to be able to switch ON/OFF the power at hand, not at the mains where things might get messy, and

c. I want it to be STABLE, not fluctuating power, and

d. I want it to be VARIABLE, not fixed.

So the rest is easy... Add a green LED to indicate ON, a mono-state switch, a filter monolithic capacitor across the terminals, and a variable voltage regulator, like an LM317 or other equivalent components. In short, everything'll look like this:

So as we go along I'll explain the tips and tricks I employed, which may be of use, since we're all about IDEAS at the first place. So here goes:

First Prototype:

VARIATOR^TM

Wall Wart (I named it for reference... Heh heh..)

So the figure shows some simple stuff:

1. Solder the male socket wiring to the Adapter wiring. In this picture, notice that the GREY insulation is there, standing by to sheath the exposed soldered part of the wiring. This means BEFORE soldering, fit in the insulation first. You can get that type of insulation from various types of wiring which has thicker wires.

2. The exposed part of the wiring is now covered properly by sliding the grey insulation over it. Take note that you have to make sure the inner part of the wiring is also insulated so that no short-circuit takes place. Note that the adapter has a tuning knob there, with fixed values from 3.0,4.5,6.0,7.5 until 21 Volts.

3. Now, add a plastic cover over all the stress points, and glue it accordingly. This makes a nice, difficult-to-break-apart socket. This means if there are any mechanical stress suffered by the socket, the wiring will out of the way, and the plastic cover will take the load. The figure below explains better:

See that the one on the left is one without the casing, so the break points are easily formed at the soldered points, rather than the one on the left, where the load is shifted to the plastic casing, reinforced with epoxy glue.

Next, a conditioning circuit is shown here:

The conditioning circuit is also a separate entity, as declared in the plan before, which fits in a green indicator LED, an ON/OFF switch, a freewheeling diode (to counter backward EMF spikes), a filter capacitor to stabilize supply, and a female USB port.

Now, why did I use a USB socket? Because I have a lot of 'em, and they don't leave room for reverse connection, which could be disastrous. The male USB connector is wired to the crocodile clips, which we'll explain in the following. USB ports have four terminals, so I combined two terminals together to get two crocodile clip terminals.

So now.... The crocodile clips. The main problem with most clips is also due to the mechanical stress it faces. So here's my design:

So the epoxy glue is very important to secure the connections. Also, the plastic casing protects the wiring and shifts the mechanical load of the wiring to itself. The USB socket is a bonus; it's strong and has only a single orientation when you plug it.

The figure above shows the transition according to the design mentioned above.

First, fitting the wires inside the plastic casing. I must warn you, it is pretty tricky to fit in the wires in such a cramped space.

Second, the clips' wiring and gluing is done.

Third, just to show when everything's in place.

So, the conclusion is that while it takes a bit more time to do this, you'll save more time than attending to the wires again and again when they break off due to the wear and tear effect.

So that's it! You have a sturdy Wall Wart for yourself and you don't need to spend much in constructing one. A variant of this (more hardcore DIY-ing) will be provided in future articles, InsyaAllah. For such a simple project, a lot of drilling down is done to provide IDEAS. So.. hopefully some of them will be of use.

All the best to ones out there struggling with their lives... May we live to please Allah more.

Jumper Cables from Junk

Ach-tung to all VE readers!!

I think I owe an apology for not regulating this site, since we're all out of the juice needed to write articles here. I'll be giving some simple, very simple stuff which no-one has done yet, at least in my circle.

Beautifulmind and Deathclaw are pretty busy engineers at the moment, and I'm kinda busy too.. but in a different way since I'm not working or continuing my studies yet, and yes, I'm going for the latter after this. So... Enough of my lugubriousness here... we'll get to the topic now.

One aspect of being an electronics hobbyist is that we'll need to channel voltage/current supply to our circuits or motors or even a single LED to a Wall Wart or a DC Supply or a battery. Rather than using wires to touch the terminals using your hands, or doing that messy temporary soldering to connect the terminals, people like to use jumper cables.

Heard of this one before?

"The strength of a chain lies in the weakest link"

This is also the golden rule with jumper connectors. No matter how beautiful or strong the grip is, you'll always end up with broken jumper connectors with the usual crocodile clips. This is because the wires are not adhered to the clips properly. You'll notice it takes more than soldering the contacts to have good quality jumper cables.

There is absolutely nothing going on here except that you'll notice: You don't need to buy the jumper cables, you don't need to be a geek to build one, and you certainly don't need to fish out three or four bucks for each jumper connectors which USUALLY don't last and will need to be repaired after some time due to wires breaking off after some time, which is due to the mechanical stress.

So.... Naturally mistakes were made, and better solutions were discovered...According to five years of experience of building my own jumper cables, I'll name a few ingredients needed for this recipe (assemble your junk collection and you'll get more options, these are only the ones I made, you might be able to make better ones):

1. Name Tag clips, which are made out of steel. They're very strong, and the grip is MUCH stronger than the generic crocodile clips., they have holes which aid in knotting or fitting in other strengthening elements. Here's my collection after extracting 'em from various name tags:

I used pliers to pull out the aluminum rivets which hold the plastic and the steel clip together. Notice that the rightmost one is an anomaly, that one is cut from plastic name tags which has the metal clip part on it. It serves a lot of purpose too.

2. Wire. (Duh!!) I got mine from radio wiring, they're very sturdy and thick, which means the tolerance is much higher if you're considering heating problems in your connections which require a large current.

To be taken into consideration: We're building jumper cables, which are prone to a lot of mechanical stress (wear and tear) so it'll be nice if you have the type of wires with a groovy and fancy-looking insulation at the end of the wire, which may be salvaged from basically all type of appliances. Something like this:

The fancy-looking "grooves" on the wire will be very helpful in making the glue bond between the wire and the clip very strong and durable.

3. Epoxy Glue: Please view this link.

The steps are pretty obvious, so I wouldn't want you to waste time reading details which don't matter, but I'll put up a single picture to show how I did it:

The picture above shows the soldering process (solder sticks pretty properly, don't worry). And a combination of the full-steel clip and the half-plastic half-steel clip is VERY useful for some applications.

The picture below are the variations of my construction for other cables:

Description:

a: The red highlighted area is the part which will be soldered, note that the wires are wounded around the upper part before putting it to contact with the metal surface of the clip. This aids additional strength of the connection after gluing.

b: The next sequence shows the contacts are soldered generously, and the "groovy" part of the fire is fitted into the hole of the clip, which again adds a significant durability to the "weakest link" (yes, in my experience, this is the frustrating part) after the applied glue to the crevices dries and hardens up.

c: This picture shows another technique used; I looped the wire around the hole (which is why name tag clips are just the thing for this purpose) and I glued the loose part.

After all of this is done, my collection is displayed as follows:

When everything's all said and done...... BOW DOWN!!! You have your own collection of the strongest type of jumper connectors for your electronics projects. Connect it to motors, LEDs (with resistors, I must remind you people), breadboards (stick a male connector into it and clip to the revealed part), and so on.

I know this article is pretty light and simple, but I find that these cables provide to be more than a chain to the missing link (intended there) which is called: convenience.

InsyaAllah, may God be pleased with us for living our lives trying to spend less (by improvising and recycling more) and use the money for better purposes.

Vizier87