Parts and PCB

Parts

Alrighty, anyone who likes to buy a lot of parts would know that Radioshack is a terrible place to go.

Compared the the prices you can find online, Radioshack is 500% or more overpriced

Plus, Radioshack is extremely limited in variety

But, what can I say. It's Radioshack. It sells cell phones.

So, being in HK I took the advantage of buying some parts in Sham Sui Po (heaven).

I went to this WECL store, bought $545 HKD worth of stuff. Well worth it: stocking up for the states!

Can you believe it? One heaping pack of resistors costed $5 HKD. Thats less than a US dollar.

Microphones, lasers, buttons, All less than one US dollar.

You can imagine how much I bought:

Sadly, and as I expected, I couldn't find flex resistors. They're hard to find: I guess I'll just have to order it.

PCB

https://drive.google.com/folderview?id=0B5gFDZ2efTDSX0hPdG5sWWJuemc&usp=sharing

That's the link to sharing all of the files. Updated.
There is a README there.

I highly recommend David Cook's Copper Connection software for hobbyists. It's free, easy to use, and tailored to the hobbyist needs.

Anyways, I'm in HK, away from my equipment, so I can't make the PCB yet.
this PCB is for testing out different sensors, so I guess it is a prototyping PCB.

The smaller PCB is for the phototransistor. It is separate.
I still need to work on deciding if I want to use flex resistors or piezo elements...

Cheers!



This is the shot clock that will change the game.

Still working!

Hello!
This is TS Wang, writing from Hong Kong.

Today we go parts shopping: many parts for the price of few parts (in the US)

While I wait on that, I have been working on my prototype PCB design on the plane and on each morning.

Once I'm finished I shall update the Google Drive folder with my recent documentation.

Oh by the way, just to get the word out, I'm using David Cook's Copper Connection.
It can be downloaded here: http://www.robotroom.com/CopperConnection/

It's great software, perfect for people who make PCBs at home. I used to use ExpressPCB, but now I use this. It's excellent.

Anyways, If anyone wants to email me at twang@ctemc.org to tell me how horrible my PCB design is, go ahead!

When the day ends today, I should have all the parts that I need for this project.

This is the shot clock that will change the game.

Decision time...

While I am in Hong Kong, I should be searching for some unique parts that might help out this project.
The predicament I'm working on currently, are the sensors.

The flex resistor:

courtesy of Sparkfun


I can use this as a voltage divider, so when flexed, will generate a voltage between 0v - 5v.
However, these are pretty expensive, and I'm not sure how sensitive they are to surface vibration (not flexing, as they will be smacked onto the back of a backboard, and on the rim.)



The piezo sensor:

courtesy of Sparkfun


These are cheap, these are commonly used, and these would be the first thing to come to mind when the two words "vibration sensor" popped-up.
There's a problem, however. They generate high voltages, for a very brief amount of time. These voltages are analog and above 5v, so my Attiny won't be able to read the whole range of voltage.
This is a good sensor to use when simply sensing vibrations, but not when it is needed to measure and compare vibrations.

I connected this sensor in parallel with a capacitor, (103, 104, I tried both, whatever was available) and it did well in lowering the analog signals that came through.

Serial.println(analogRead(A0));
like so.
The printed values ranged from 0 - 30. the maximum value Arduino can print is 1023.

I noticed, however (with and without the capacitor) that when the sensor was at a low state, the numbers kept creeping up, for example

1023
300
301
300
305
900
1023
1023
1023
350


Do you notice how the numbers just keep rising when it is at the low state (300 - 400)?
This isn't too good, as I will be comparing the voltages of two sensors. If this happens:

Backboard sensor: 301
Rim sensor: 304

the shot clock would reset. Not good.






Something else:

Maybe some expensive accelerometer might solve the problem, or something that will sense EXACTLY where the ball hit, just like humans can.




********************************************************************************
other than that, I am currently researching where to place the backboard sensor on the whole wide backboard. Does it matter; is there a significant difference to where I place it?

I'm finding out.




This is the shot clock that will change the game.

Hong Kong Shopping - Parts

I have been in Canada for a week.

Next week, I shall be in Hong Kong, which is a great opportunity to search for cheap and hard to find parts.

I can definitely find the some sort of flex sensor, the laser, and anything else I might need.

I will keep you updated!

This is the shot clock that will change the game.