Arduino Icons

Here are Aarduino boards in icons for those who like to have it. (transparent background)
link for zip file download 

Logo 400px

Logo 1000px

Logo 48px.ico

IDE 48px.ico

Nano 495px

Uno 795x575px

Uno 48px.ico

Nano 48px.ico

Digispark 303px

ProMini 350px

ProMini 48px.ico

Digispark 48px.ico

Portable stereo speaker (digital amp) 5V 3-5W

I was never a fan of internal speakers on phones, even the best of them. the sound is always jarring and too strong in the 1-5kHz band. whilst they rarely can reproduce frequencies under 500Hz. and that is mainly due to the fact that physics is a harsh bitch (the size of the speaker and speaker box dictates the resonance range and hence power output at various frequencies).

So, what's a man to do? well that depends to the type of man. some go and buy a cheap compact speaker that sounds shite, some buy expensive ones (ex. Logitech UE series $100-$400) and live with what has been made for them, OR, he makes his own damn speakers! with all the features he wants and none of the nonsense he doesn't. 

[after 9 months of regular use]

So, here are my criteria:

Want

• Simple and robust
• Wired connection
• Potential for upgrades and add-ons
• USB rechargeable
• Long runtime
• Repairability
• Modular

Don't want

• Complication (fidgeting with bluetooth, pairing, hold buttons for on/off or functions, etc)
• Loads of controls that rarely get used
• Large or heavy
• Short battery life (high standby current)
• Heat management 

Our chip of choice is PAM8406, class-D amp with %90 efficiency and 3W Output at 10% THD with a 4Ω Load and 5V Power Supply. (originally I had made this with PAM8403, it turned out my parts could handle more so I upgraded).

Parts:

• ABS project box (ebay) ~$5
• Speakers (ebay) ~$5
• Amp module (ebay) ~$4
• Boost circuit (ebay) ~$1
• Battery li-ion 1000mAh (salvaged off rc toys)
• Caps 6.3V, 1500/1800µF x 14 low ESR (salvaged off old motherboards)
• Sockets, pot, leds, resistors (almost all salvaged)
• Wires (pc power supply quality cables - salvaged)
• Copper Heatsink (made of reclaimed metal)
• Paint, hot goop, cardboard, screws, etc (more or less free :D)

Notes:

• Battery has protection circuit on it
• Amp doesn't make enough heat to cause trouble with the battery underneath
• Boost circuit gets a bit toasty at full output (used what I had handy, needs upgrade)
• Panel could have been done cleaner, alas, "ain't nobody got time for that" :D
• Base funnel/tube was helpful but not hugely. according to online calculators, with my box size and the low frequency response I wanted, to achieve resonance, tube needed to be +60cm long. my box is 16cm long total soooo ¯\_(ツ)_/¯ 
• This speaker has much fuller sound than a phone speaker and gets much louder but it's no sub-woofer (physics being a bitch and stuff) lower band is around 200Hz before output starts to take a dive

Future upgrades

• Replace the battery with one 18650
• Swap the charger module with one that has micro usb (instead of mini) and has onboard battery protection 
• Redo the volume knob
• Redo the lights and light pipes

Archery Target Frame build and Target Core repair

= Disclaimer =
This is not a tutorial nor a step by step guide. this article is meant for clubs, experienced archers and makers as reference material.

Alright, so, our club bought some new targets and the old ones had to go. the cores were pretty much gone but the outer circle was still usable.

I salvaged some high density foam from another old target and used gel contact cement and a brush to apply it to each layer as I rolled the foam. having someone around as an extra hand in this step will help you a lot as you need to roll the foam pretty tight and foam will fight you back :) once rolled to size (just about a centimetre oversize actually to get a snug fit) tied it up with a few straps tightly and let it sit to dry for a week or so. core goes in as you see here.


In the meantime I went about making the frame/stand for the target, I used 4.5cm x 7cm treated pine and a sheet of 9mm marine grade plywood. I used galvanised hardware, if you can spare the cost go for stainless. 

This is the plan and dimensions I took off of club frames. keep in mind to get the target centre height right (for competition standards) for different targets you may need to modify the height a little.

Three items that are not shown here are ground anchors:
Target needs to get tied tightly to the frame, we tie the targets to frame by a piece of rope and using the four rope loops you see on the target, from the back tied ropes would look like a plus sign.

To reduce the risk of target toppling over when people are pulling arrows we always anchor our targets with a 4m rope from the top of the frame on the back side to the ground with a large (40cm x 12mm) peg. the peg needs to go to the ground in an angle pointing away from the frame to support the rope properly.

Lastly, we had eye bolts on the lower side of the legs to peg the frame to the ground directly if need be. we rarely needed to use those though.


As for the rest of hardware bits used:
Bolts for the hinges on the top of the frame
I used 2 long bolts with 2 nuts and 3 large washers each.
They go on like this:
bolt head > washer > timber > washer > timber > washer > nut > nut

The main idea here is to have a washer between the timbers to let them slide easily and act as a hinge.
As for 2 nuts that go on each bolt, the first one is the nut and the second one acts as a lock nut, you need to put the first nut in and move it to where you need it, then hold that nut with a wrench and tighten the second nut onto the first, that would lock them in place.
Obviously there are other ways of doing this as well.
 
For the target support bars I used 2x50cm pieces of medium duty 2cm x2cm square tubing. they were attached by 3x7cm roofing screws each , 2 to the side and one to the top.

In this case I didn't need the bars to be removable, if you need them removable (so you can easily put it in storage) then you got to make a pocket with a larger steel tube to accept the support bar. you also need a pin or similar solution to hold the bar in place, you do not want the bars to move on you or fall off. target itself weights over 30kg, the frame is not much lighter either.

As for the rest of screws, Used a bunch of 4cm chipboard screws to attach the plywood to the frame, those plywood triangles help a lot with making the frame rigid.

Also a bunch of 15cm self drilling Bugle Head Batten Timber Screws to screw the frame timber itself together, 2 for each joint. these are a bit overkill but they were needed since I didn't want to use any fancy wood joining techniques or wood glue.

=====>> Source files are here <<=====

And here are some additional pictures of the build for reference.

Update:

2 years on in the open and no sign of wear on the frame

Rotary/Quadrature Encoder Hi-Res and Vector patterns

Hey all,

I designed these Optical Encoders a few years back for a project I was doing. you can print these on transparency sheets and depending on the pulse rate and accuracy that you need you can cut the outer grids off. for printing use the PDFs or Adobe Illustrator vector file below.

=====>> Here are the High Resolution and source files <<=====

To read these properly you will need to use an Optical (phase) Encoder. OE will let you do single and double precision count as well as detecting the direction of rotation.

I originally intended to use them with photo-interrupt type sensor. while it worked it was not very accurate and had no direction information available, and that sometimes is good enough.
With a slit window and good amplification you can use them with reflection type sensors as well, in which case you might want to print them on white sheets.

Saving location of icons on your desktop after moving or organising

I generally keep all the stuff that I'm working on or meant to be working on in the near future on my desktop, I also like to organise the icons into groups in various corners of the screen and also in various monitors (I have 3).

Ok, so far so good, but for all that careful organisation of the icons to get saved by windows and come back after a reboot you need to logout/shut-down/reboot successfully and log back in, I find that rather tedious and impractical, besides, what happens if your computer crashes or reboots on it's own? all that effort will go to waste.. (yeah I hardly ever turn my computer off, it usually just crashes after a few days on it's own, aw... I miss linux...) anyhow, in my frustration I stumbled across a rather handy solution to save the modification right after I'm done with them.

You probably already know about the F5 key being the refresh short-cut for windows explorer and most browsers. but sadly a refresh doesn't seem to make windows explorer to memorise the location of the icons on the desktop. you also may or may not know about the "Windows key" on the keyboard, there are a bunch of handy short-cuts associated with it. one combo that seems to have been missed by everyone is: 

WIN + F5 = Refresh Explorer and save state

I usually do a CTRL + F5 before doing the WIN + F5, I hadn't bothered to confirm but I think I does something akin to a "clean refresh" as it's done in most browsers.

One possibility is that ctrl+f5 is the combo that does the save action but have not bothered to test them separately before, if anyone out there cares to test it I would like to know the results.

I have been using the combo for years and it seems to work on all windows versions from XP to Win 7, let me know if it works for you as well.