Mini Tables

A while ago I got a load of old Lacie hard drive enclosures, 1 or more of disks inside had died and it fell to a friend of mine to extract any good hard drives and I was offered the carcases.

mmmm...free Junk 

Looking them over I figured there was some nice aluminium and a few fans might be worth having.
Having them knocking around In my lounge the large ones instantly found use as a small  tables, so I poshed them up a bit:

Classy! (yes, that is a plater as a coaster!)

The top is some reclaimed 1x4" white wood (spruce) planed all round board wich has been stained and then varnished with some polyurethane ultra-hard varnish.

The case was sprayed with some satin black rattle-can paint (no primer, just straight down on the original paint, it seams to be gripping really well). The T slots in the edge are a challenge to paint but many light coats from multiple angles give the desired result, and they tend to be in the shade and hence not show up too badly (I thought I had got these but the camera flash shows them up pretty bad, I struggle to even see this with a torch IRL.)

Bottom View

The top is held on with some 20mm x 20mm x 1.5mm aluminium angle. I got this from screwfix (21869) wich is far cheaper than the first place I found it (home base, altho the hombase stuff did apear to be anodised unlike screwfix's plane vanilla aluminium). Not wanting to change the outside I guled the aluminium angle to the case with Araldite metal epoxy. I prepped the surface with sand paper and a stanley knife to try to give a good key. I also drilled the aluminium so that the glue extrudes though the holes kinda forming rivits. This was then allowed to cure for 24 hours to ensure a good full set on the epoxy before the wooden top is screwed down.

The top is just screwed down with ordinary wood screws, be careful not to over tighten them (I got bit keen at one point and was greeted with a loud crack, whoops!)

In it's natural Habitat.

One of the things I like about these is they are just the right size to hold a cup of tea (if you are lounging on the sofa you cant quite reach the floor with ease) and fit under the arm of the sofa (out of the way, less chance of kicking your brew across the floor!).

Joule Thief Testing

While trying to get my Joule Thief to work I brought in/wound several coils. Having these coils around I decided to try out various coil and transistor combinations to see what does and doesn't work. Maybe this will help out other people who are looking to build stuff (on the other hand maybe it won't, meh).

The Coils

From left to right:

• Big Clive Coil, 12 turns of double wound (both wires wound together, 12 turns on each) 38swg enamelled wire (e.g. YN91Y) on a small ferrite bead around 3.5mm OD, 1.5mm ID and 5mm long (N88CU in fact) on a pice of strip board for easy bread boarding.
• A common mode suppression choke (a 26-708), 37 turns of 0.5mm enamelled copper  on each side of a ferrite torroid 25mm OD, 14mm ID and 10mm long
• A salvaged ferrite (from a Lacie HDD cady) wound ala MAKE/EMS. 7 turns of 7/0.2 hookup wire on a 15mm OD, 8mm ID and 7.5mm long
• A Crude coil of 7 turns of PS2 keyboard cable on a ferrite (from a 26-8018) 27mm OD, 14mm ID and 11mm long. The PS2 keyboard cable has 4x 0.7mm wires in the middle with a foil and single wire shield. Because of the multiple cores they can be wired in two pairs (7 turns), or in series with another wire (14 turns)

Theses were paired with NPN transistors I happened to have knocking about:

The Transistors

From left to right:

• PN2222a (TO-92 case)
• BC107 (TO-18 case)
• BSS52 (TO-39 case)
• BFY 50 (TO-39 case)
• TIP31A (TO-220 esque case(may not be a 220 but a 257?))

The other components are a 1/4W (I think metal film) resister of unknown origin,  and a white LED (55-2484) the stupid brightness is probably not needed here but it's what I had to hand.

I  tried every combination of coil and transistor giving these results:

• PN2222a, all coils work well exception the common mode suppression coil wich gives a very dim light.
• BC107, all coils work and give good bright light.
• BSS52, all coils work and give good bright light.
• BFY50, all coils work and give good bright light.
• TIP31A, only works with the common mode suppression coil giving good bright light. Bupkis on and other coils.

Clearly there is some thing about the common mode coil that is ideally suited to the TIP31A but not to the PN2222a,  maybe something to do with the gate properties? The common mode coil has the most turns of wire but also probably the worst coupling (with the coils wound on oposite sides of the torrus instead of next to each other) wich is interesting, I might return to this when I have a scope.