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16  Using Arduino / Project Guidance / Re: Serial Controlled RC Car on: May 31, 2011, 11:49:43 pm
Hi Andrew, This is certainly doable and there are many examples out there.  I'll look thru my notes..

I am working on a 2-motor car / robot that will receive serial signals and run them as "LOGO" code.  See

Obviously it would be best to have a radio link for this, but you can start out with storing a series of commands in the robot and then letting it go..

So the most common commands would be:

FW 100     (Forward: The numbers are distance, you have to decide what that scale is!)
RT 90    (Right Turn (degrees]
BK  200  (Back)
LT  180  (turn around)

etc... See the Logo information.

That might be enough to start.

Logo also has simple repetitive commands, so:

REPEAT 4 [FD 200 RT 90]   travels in a square 

Logo has the concept that the vehicle has a pen that can draw on the ground / floor / paper.  I've seen some draw with chalk on the sidewalk  smiley

So those commands are PENDOWN and PENUP  usually abbreviated as PD and PU.

All/most Logo commands have 2-letter abbreviations that would be good...

I plan to have two more commands:

GA  (Go autonomous: according to onboard software and sensors etc. you develop)
SA  (Stop autonomous: return to remote Logo commands)   Possibly triggered by a hard-contact crash!

Another 'new' command usually is SP 100  (Set speed)

Let us know how you're making out with all this...

I have several different sensors etc. that I'm testing that are available here:

DISCLAIMER: I mentioned stuff from my own Shop...

17  Using Arduino / Project Guidance / Re: Basic Telemetry Design For Solar Car on: May 31, 2011, 11:26:33 pm
If you're doing it as a cost saving exercise then you'd be best off buying a 'non-arduino' board such as one of the versions from seeedstudio or similar.

Some options here including copy of MEGA:

You may find some of the tutorials / info helpful also, such as this on temperature measurements:

DISCLAIMER: I mentioned stuff from my own Shop...
18  Topics / Education and Teaching / Re: Suggestion: mention breadboards in newbie tutes. on: May 30, 2011, 11:19:04 am
This is a good point; there are many different types and sizes of Breadboards these days...

I have a beginning of a general Breadboard page here:

I will work on photos / info about the different breadboards...
19  Using Arduino / Project Guidance / Re: Interactive Art Object Using Arduino+PIR sensors, which parts to buy? on: May 29, 2011, 09:41:12 am

The sensor looks right.

I think the motor is a little confused.  The Motor has basically 2 terminals you are going to use, right? "GND" and (Pick one of "FAST" or "SLOW"??)..  so you need to be able to reverse the connections to BOTH terminals. I would draw it like this:

Tell us if this makes sense??

--- 1 Relay makes it run one way, other relay makes it run the other way. NO or BOTH relays is stop....
20  Using Arduino / Project Guidance / Re: Humming of PWM dimmer on: May 29, 2011, 02:06:22 am
Hi, Do you have an oscilloscope to look at the FET gate waveform?? 

I bet the 10K can't pull the gate up fast enough.  Try 1K, or have the isolator drive another transistor that can pull 220 ohms down.
OR use a "Power FET Driver chip"  .

Let us know what you find...
21  Using Arduino / Project Guidance / Re: USB - serial chip other than FTDI? on: May 29, 2011, 02:01:52 am
Thanks guys, for the valuable Voice of Experience on USB chips... !
22  Using Arduino / Project Guidance / Re: Arduino controlled clothes washer on: May 29, 2011, 01:58:14 am

You might find this 8-relay board cost effective (< $20 in quantity 10 or so..):

Hopefully 8 relays would be enough... 

The optoisolation also means you don't have to worry about your Arduino so much  smiley 

DISCLAIMER: I mentioned stuff from my own Shop...
23  Using Arduino / Project Guidance / Re: USB - serial chip other than FTDI? on: May 28, 2011, 02:12:19 pm
The FTDI is far superior to the Prolific.

Can you tell us what the differences are and what matters? 

I'm about to test Prolific PL-2303 and Silicon Labs CP2102 USB interfaces.  So far they and FTDI are equally functional for RX-TX use.
The CP2102 has a 3.3V output (100ma) and 5V tolerant inputs, and Arduino Reset )(For $5.75)  So I'm wondering what else $15 gets me at Sparkfun...

Have you had problems with Non-FTDI manufacturers?

24  Using Arduino / Project Guidance / Re: What is this? on: May 28, 2011, 01:57:22 pm

Two things:

- An Arduino Input has an impedance of about 100 Megohms, so I think you are just seeing noise coupling when you lift the breadboard off the table.  Is the table metal underneath??  Hmmmm.

- Second, you are not Being Nice to your Arduino by plugging an LED directly into pin 13 and ground. You are causing more than the maximum of 40 mA per pin to flow.  UNLESS you have one of those few LEDS with a built-in resistor.

25  Using Arduino / Project Guidance / Re: Arduino controlled clothes washer on: May 28, 2011, 01:51:21 pm

Over on the left, out of your photo of the schematic is a state table that shows the sequence for the different timer sections.  If it's a NICE one it shows which contact points are active during those sequences. From that you should be able to learn what the timer sequence does. 

I'm wondering just how the motor is reversed. Or does the Start winding just get reversed.

Not to tempt the Washer Gods, but it's been a long time since I took a timer apart and 'fixed' some contacts...
26  Using Arduino / Project Guidance / Re: Starting an Arduino Advanced Charger and Analyzer for NIMH batteries, How? on: May 28, 2011, 01:41:40 pm
Hi Adrian,

Are you planning to have 'fast charge' capability?  If so I think you need both terminal voltage and current per cell?

So a MEGA with the 16 analog inputs for < $30 might be good... 

But why would you want to do this, for AA's etc.?? Good cheap chargers out there.

UnLess you will also do Amp Hour testing and logging. THAT's the charger I want.  I built one a few years ago for testing / charging 12V NiCad packs, but it's 1 circuit and runs on a DOS PC. Ancient History.

What are your ideas??
27  Using Arduino / Project Guidance / Re: Servo Motors on: May 28, 2011, 01:29:13 pm
Hi, Also look at:

These are already set up to run "Continuous Rotation" for Robot drive wheels.  Check shipping prices for where you are...

DISCLAIMER: I mentioned stuff from my own Shop...
28  Using Arduino / General Electronics / Re: MOSFET for high speed PWM on: May 28, 2011, 01:18:29 pm
Alright! I'm curious to learn of your results.

Me Too!

I THINK most 'Regular' Red / IR LEDs are relatively linear with pulsed current VS radiant output, up to some point.

If so, for IR communication / beam detection the (unknown to me) question is the RECEIVER response and how that works into the equation.  ie. does twice the pulse current give twice the response, or can the pulse be "too short"??

White LEDs etc. that have a phosphor that indirectly produces light CAN be pumped to higher levels with short pulses and give a beneficial non-linear response to short high-current pulses.  I read somewhere.

No question that pulsed IR beams are far more stable and long-range with tuned receivers than simple on-off source / receiver. These are cool: when you need to have a beam several meters from the transmitter to receiver. 

I want to experiment with an infrared laser for long beams.  I'd like to design a product that includes a visible laser you turn on temporarily to align the transmitter to the receiver. Then the Invisible beam can trip your camera, etc...
29  Using Arduino / General Electronics / Re: MOSFET for high speed PWM on: May 28, 2011, 07:41:04 am
Hi Tom,

Interesting question....

The Frequency of 40 KHz is no problem for Arduino. Making a pulse with a width of 100 nS (One cycle of 10 Mhz) would have to be done differently.

So, the pulse width part:

The idea is to have Arduino do the repetitive frequency and have one 'edge' of that signal trigger a pulse.  You can use a chip for that, a "Retriggerable 1-Shot" such as 74HC123 I think might be OK..   See:
The data sheet says that timing components of 2K ohms and 30pf gives a pulse width of 100nS.  You can vary the pulse width by varying resistor and capacitor values.

Now, that's the Old Skool way of doing it for a couple dollars. .. Anybody else?? 

The MOSFET question:  Basically a  smaller FET (you don't need 50 Amp drain current capability)..  Not my expertise.. Anyone??

30  Using Arduino / Project Guidance / Re: USB - serial chip other than FTDI? on: May 28, 2011, 06:13:07 am
Here's the 2303 already soldered with a crystal and USB connector for $4.50  and $4 in quantity 10 ..

...just solder it in or use double-stick foam tape??

DISCLAIMER: I mentioned stuff from my own Shop... (My solution to everything  smiley  If you find a good solution I don't have, let me know!)

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