27/49mhz RC. Seems no one uses it.Reasons?Country?

Alright, take mercy on me if this seems to be a ::) type question, but I come from a mechanical background. Its only been with the advent of affordable microcomputers that electronics/robotics has become a viable hobby.

In the US, I can get an R/C car for $10, including 8 1.5v batteries (12v for car) and a 9volt for the controller. The standard operating mhz is either 27 or 49mhz. Why do I find so few results when I search for projects that use these?

At first I thought it was because it would be redundant to use an arduino rather than just run an H Bridge from the receiver, but as I've read more I see that the arduino can be used to read input from sensors and has many applications in being placed between the reciever and the H bridge, so I know thats not it.

Then I noticed many posters are not from the USA, and I have no idea what your duties are on extremely cheap chinese imports, or what the standard mhz was for those countries, and am thinking perhaps this is why I can't seem to find many projects involving them?

Should I be searching for a different mhz in place of 27/49 if I want to find good information? Is there some sort of danger in using this band?

Basically, I am having a hard time understanding why people will pay 5-10 times what a complete car costs for just the transmitter and receiver, and trying to understand what piece of information I am missing from my current understanding. (I can 12v all day, but digital and programming is still very new to me.)

Thanks very much.

edit: I forgot, another disadvantage of these cheap R/C cars is that they only have ON/OFF for speed settings, and that could also be a possibility i thought.

The 27/49 MHz RC cars and such uses a special purpose chipset designed just for remote control toys. It's not necessarily easy or even possible to use them for general purpose data communications. You should be able to find some more information on some of the RC forums; there was a lot of interest in converting/enhancing these for custom modeling applications. (if you can figure out the right keywords. Try "bitcharger conversion" : http://www.rcgroups.com/forums/showthread.php?t=84771 )

Also, radio has weird legal issue attached. Just because a given band is 'license free' for use by remote control toys doesn't mean that you are ALLOWED to use that band for other purposes (like data transmission.)

And the $100 radios you're talking about have much larger capabilities than the 27MHz remote control radios. You might get a couple hundred bits/second out of a cheap remote control (10 values/s times 3 channels time 8 bits, or so?) in one direction only, compared to the ~10Mbps receive and transmit capabilities possible for an 802.11 wireless networking board.

Richard mentioned the JeeNodes that are essentially arduinos with lower-capability radio at prices similar to an arduino...

Thank you both for the very detailed and concise responses. They cleared up a lot of my confusion. My main reasoning for wanting to use these chipsets were that i have several of them sitting around, I don't fully understand what I am doing yet, and I'd rather "blow up" these cheap parts as I climb the learning curve than spend big money and end up blowing up something of value.

The link to the rcgroups forum as well as the right keywords are a godsend.

If anyone has any (printed) books they can recommended, that would also be great. Old textbooks cost practically nothing on amazon, and my knowledge has gaping holes in it. Thanks again.

My main reasoning for wanting to use these chipsets were that i have several of them sitting around, I don't fully understand what I am doing yet, and I'd rather "blow up" these cheap parts as I climb the learning curve than spend big money and end up blowing up something of value.

Reboticon, now you start to make sense. When you were wondering about what other people do or don't, it was somewhat academic and of little value. If something obvious isn't commonly done, most likely there's a very good reason why the obvious thing isn't working as one thinks. But that doesn't necessarily mean that the it can't work for you.

If you want to use one of the Chinese toys from your heap of stuff for one of your projects, that's perfectly fine and reasonable and has been done many times before. It's also a good exercise in reverse engineering and documentation research and very likely, you will get helpful pointers from the nice people on this forum if you provide enough data about the parts and what you want to achieve with your project.

Korman

Thank you. I realized there was some reason why these weren't being used for "real" projects, but with my limited knowledge it wasnt clear to me. Right now I am trying to interface a 49 mhz with the arduino, while also reading several arduino books and "An Embedded Software Primer" by David Simon. Its an older textbook I got for very cheap off amazon.

My MAIN objective in this project is to simply write a few working sketches to better familiarize myself with the Arduino code. My coding experience is entirely in BASIC and MATLAB so the C derivatives are taking some getting used to. Most of the arduino project books I have purchased seem to deal almost exclusively with LEDs, and there are so many different ways you can make an LED blink before it becomes beyond boring ;)

A few more questions. Again, If these questions make you go "huh?" Its because I don't fully conceptually grasp all the things I am working with, and am trying to fill in the holes. Reading books is great, but I tend to learn best through hands on trial and error and asking questions of those whose knowledge is much greater than mine. (While hoping they understand that I am a quick study who is not simply wasting their time and refusing to research myself. I simply don't even know where to begin for much of this. If its something you've seen discussed before, a simple link or forum name is more than adequate. I'm not trying to burden anyone, and you will find me to be extremely appreciative of any insight offered.

I am an ASE Technician (cars) and I specialize in retrofitting older cars with newer EFI systems as well as custom work such as welding. So I have some background in electronics, and understand the "whole" picture better than the individual parts. I will also be using a lot of car analogies, because it makes it far easier for me to understand.

Now those questions ;D Digital and Analog. There is still some gray area here for me. Is digital always going to be either HIGH/LOW on/off while Analog is going to have a varying value? When I socket and chip an Eprom on a Honda ECU, I understand that those pins are digital I/Os, much like arduino, but I don't really understand why.

For example, a camshaft position sensor or a crankshaft position sensor is a hall effect sensor that will pulse 5v, so that makes it digital, is that correct?

On the other hand, a typical MAP (manifold absolute pressure) or TPS (throttle position sensor) is going to have a 5v reference voltage but is going to output between 1 and 3v or 1 and 5v depending on manufacturer, so because the signal is changing its analog?

I realize that seems extremely basic, but it is rather vital that I have a solid grasp of the concepts, and currently Im still :o

Second, Is the Vin pin on the POWER part of the arduino always going to give me 5v, or is it currently giving me 5v because I am running it from a USB port, but would give me 9v if I ran it from a 9v adapter?

I realize I am all over the place as far as topic here, but Im trying to just keep everything all together, as to not clutter the front page. I don't really know what the preferences are here, and if starting a new thread is better, let me know.

Here are the basics of my first project. I have a 49mhz RC car that is complete. As stated I am a "learn by hands on and mistakes" type, so I removed the motors, desoldered the power/ground, and ran them to my arduino uno using first the 5v power and then the 3.3v power and charting the resulting voltages. I measured at both the IC pins, and the Motor signals after they have run through some transistors ( I havent really figured this part out exactly, it uses through hole on one side and SMD on the other and im having a heck of a time tracing it)

I was able to trace which button on the transmitter corresponds with which IC pin and which of the 4 motor leads.

My goal is to connect this to the arduino, and have it display( through the serial port) digital ON/OFF at particular digital pins based on which button is pressed.

Now, I want to first attempt to write this sketch myself, but is it possible to do this using either the IC pins OR the motors signals after they have run through the transistors? Im not asking which way it SHOULD be done, I want to know if its possible to do it both ways, because if so I will try to write both.

Is it possible to write a sketch using either method with just the basic commands I have learned from my Getting Started With Arduino book, and/or are there specific commands that I should really pay particular attention to and investigate?

Again, Thanks for reading one of my novels, and any help you can give me! [smiley=thumbsup.gif]

Is digital always going to be either HIGH/LOW on/of

Yes.

while Analog is going to have a varying value?

Not necessarily varying, but one of a range of values from 0 to 1023.

Like tire pressure. The tire is not either properly inflated or flat. There are possibilities in between.

For example, a camshaft position sensor or a crankshaft position sensor is a hall effect sensor that will pulse 5v, so that makes it digital, is that correct?

Yes.

because the signal is changing its analog?

A digital signal can change, too. But the MAP or TPS sensors can output a range of values, so they are analog.

Is the Vin pin on the POWER part of the arduino always going to give me 5v, or is it currently giving me 5v because I am running it from a USB port, but would give me 9v if I ran it from a 9v adapter?

The Vin pin will measure whatever the input power source is (it's where you input an external voltage - in = input).

if starting a new thread is better, let me know.

You're doing fine.

Awesome awesome, thank you guys so much! That really helps a lot of the conceptual pieces fall into place for me, and now I can concentrate on "tinkering" and understanding individual components with much less stress of frying things. Im Old Hat on several car forums, and I know how tiresome it can get to answer questions that seem so basic after you have accumulated as much knowledge as you all have, but to get confirmation as a newb is invaluable. Thanks again for taking the time, Now im off to start trying to sketch ;)

Alright, I got my first couple sketches working, and though they are simple, it took me quite a while ;) They also left me with more questions. I realize they are software questions but I didn't see a need for a new thread, especially because I think these are simple questions, but I could be completely wrong. I've included my code, and most of the questions are in the comments, but Ill ask them in regular text to make it easier..

First thing I did was just connect my pins (from RC car) to analog 0-3 and wrote a sketch that would just serial output the values, with a delay(5000) so I could read them. I did this because I don't understand how/why digital pin value has 255 integers and analog has 1024. I realize an explanation as to how/why this is may be way to much to explain in a post, but a book recommendation would be great. I don't even know what to look for.

Then I changed the code to make the analog inputs be on/off for digital pins, and learned some more stuff. First problem I ran into was not using ELSE statements, and my LEDs would stay on after the button was pressed. At this point I pressed both buttons(for one set of leads) at once triggering double LOW and arduino DID NOT LIKE that, but worked fine after a reset. If I blow something up, am I likely to blow up the IC (of which I bought a couple extras in case) or is it going to pop part of the actual PCB?

After looking at my code, it seemed like it would be much shorter if there is a WHILE command. Is there?

Finally, I liked having the delay(5000) for the serial port, but I could not figure out how to make the serial print delay, without also making the rest of the program delay. Is this possible with a small amount of code, or is it something I will just have to wait until I am more familiar with the language and syntax?

As always, thank a million for any insight.

//trying to add to my first sketch. I want the analog values to //trigger digital pins high/low when a zero is read. // variables are named because the wires from board are labeled // FM and BM, and RM and LM. Board is powered from 3.3v pin.

define FMinput 0 //ForwardMotion button

define BMinput 1 //BackwardMotion button

define RMinput 2 // Right Motion/motor

define LMinput 3 // Left Motion/motor

define DigiFMsig 9 //Digital FM

define DigiBMsig 11 //Digital BM

define DigiRMsig 5 // I know this isn't PWM but it seems like good

define DigiLMsig 6 //habit to use them for outputs?

int FMval = 0; //analog value 0-670ish, only 0 when BM pressed int BMval = 0; //Opposite of above int RMval = 0; int LMval = 0; void setup() { pinMode(DigiFMsig, OUTPUT); pinMode(DigiBMsig, OUTPUT); pinMode(DigiRMsig, OUTPUT); pinMode(DigiLMsig, OUTPUT); // The reason I serial here is because it helps me to understand //the relationships between digital and analog signals of //256 vs 1024 which isn't in my background Serial.begin(9600); }

void loop() { FMval = analogRead(FMinput); BMval = analogRead(BMinput); RMval = analogRead(RMinput); LMval = analogRead(LMinput); Serial.println("FM Analog Signal Increase with Button S4 yellow"); Serial.println(FMval); Serial.println("BM Analog Signal Increase with Button S3 white"); Serial.println(BMval); Serial.println("RM Analog Signal Increase with Button S2 Blue"); Serial.println(RMval); Serial.println("LM Analog Signal Increase with Button S1 Red "); Serial.println(LMval); Serial.println(" "); //Originally I had delay(5000) here, but It seems it would delay //everything by 5 seconds instead of just the serial print. Is //Another Loop statement needed if I want to serial print with //delay? if (FMval == 0) { digitalWrite(DigiFMsig, LOW); digitalWrite(DigiBMsig, HIGH); } else { digitalWrite(DigiBMsig, LOW); } if (BMval == 0) { digitalWrite(DigiBMsig, LOW); digitalWrite(DigiFMsig, HIGH); } else { digitalWrite(DigiFMsig, LOW); } if (RMval == 0) { digitalWrite(DigiRMsig, LOW); digitalWrite(DigiLMsig, HIGH); } else { digitalWrite(DigiLMsig, LOW); } if (LMval == 0) { digitalWrite(DigiLMsig, LOW); digitalWrite(DigiRMsig, HIGH); } else { digitalWrite(DigiRMsig, LOW); } } // Obviously the digital signals will have to run to an H Bridge // of some kind to power motors, but for now they are connected // to resistor + LEDs as suggested for learning ;)

Hi, I'll take a stab at some of your question

I did this because I don't understand how/why digital pin value has 255 integers and analog has 1024.

The digital pin has LOW or HIGH. Nothing else. Everything inside the Arduino (or any other computer) is a number, we just choose to interpret some numbers to mean something. I do not care what number is used for the digital values HIGH or LOW (it might be 0 and 255). I just use the codewords LOW and HIGH when working with digital input or output.

if (digitalRead(..)==LOW ) { ...
valx := LOW ; digitalWrite(pin,valx) ;

Your own earlier mention of the crankshaft sensor is digital if all you know is when the crankshaft is at the top position (it outputs HIGH) and else your somewhere else (it outputs LOW). To make use of it, your Arduiino code would look - very often - at the pin-value and do something (f.eks. add one to a counter to count number of revolutions) when it turned HIGH.

The analog values from the analog input pins is limited to detecting 1024 distinct voltage levels. It is the way the circuit is constructed. So whatever the voltage is (between 0 and Vref/5V), the analogRead() will give you the nearest 1024th value. You would have to know what the voltage measured, to give the number (f.ex) "734" meaning - it might mean 80 degrees (temperature sensor) or 57 Tons (pressure sensor). On your RC controller it probably represents how much the stick is pushed. As the number only can positive, one usually offsets: 0-1023 means -511 to +512 (as an example)

and arduino DID NOT LIKE that ... pop part of the actual PCB

If you only use the 0-5V from the Arduino, your powersupply and the RC stuff, you are very unlikely to blow anything. The chip is quite well protected, but it is not unbreakable. If something gets hot - unplug!

You will probably make many programming errors (I do) and some may appear to freeze your Arduino. Pressing the Reset button should always get you back to start.

serial print delay, without also making the rest of the program delay

This is a trickier question. Basically you have to write your program so it does NOT use delay() but by looking at millis() work out if it should skip or execute the Serial.print. Look at the tutorials http://arduino.cc/en/Tutorial/Blink and http://arduino.cc/en/Tutorial/BlinkWithoutDelay, they show this technique applied "before" and "after".

As a minor side issue, when you call Serial.print, the Arduino does nothing else in your sketch whilst the Serial is printing, ie. it will not loop through checking the other pinvalues. (There are ways around this, but requires far more explanation) It will not matter to most programs, but keep your prints short, and/or set a high baudrate.

Actually analog returns values from 0 to 1023 (the output of the Analog to Digital converter, ADC) But digitalRead() returns only HIGH or LOW (one bit, 1 or 0). Dunno where your notion of 255 comes from?

Perhaps you are seeing that when a variable contains "LOW" or "FALSE" then its numeric value is 0, and when a variable contains "HIGH" or "TRUE" then its numeric value is 255 (all bits on). But the value is 255 (or "FF" in hex) so that when you say NOT, it flips back to zero.

Yep! You 100% reverse engineered my way of thinking there ;D Also, I am looking at example 04 from "getting started with arduino" by Massimo Banzi and from what I thought I understood about the example 04 code which fades an LED in and out, the PWM pins can have a value of 0-255? I realize (and commented in code) that I wasn't using PWM here but doesn't it mean that the digital can be 0-255? Just not in this case? The getting started book also makes a point about dividing an analog value by 4. After reviewing some of these example codes i do see that even though they are using the digital pins, they are using AnalogWrite(), is that what I am confused?

Note that delay() is OK for fooling around and experimenting, but it is NOT recommended for "production". Instead, see this tutorial: http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay

Excellent. Printing Now. Thank you.

What exactly is the nature of the receiver outputs? Is it simple on/off? Or is it variable/proportional like PWM, perhaps? (That is one downside of using undocumented hardware). Or do you have the data sheet for the receiving circuit(s)?

No datasheets, i searched for quite a while. Its a 16pin 2x8 IC with no english markings. Even browsing just 49mhz ICs they all seemed to be 18 pin. The chip itself is through hole but the other side of the board is all SMD, so the leads I am using are after the transistor bridge. Basically, If I was actually giving the receiver the 12v it normally sees, It would spin 2 tiny motors that seem to have the same specs, the steering motor just uses a rather intricate gearing system (1:300 final maybe?) to make it work. Im not really concerned with getting this to do anything. After seeing the range, I understand why a NICE set would be needed for anything real, this is just all about learning. Basically, I have very very little computer AND component knowledge. My computer knowledge comes from the days of DOS and having to make 100 different 3.5 boot disks to play whatever game I had bought from the used game pile. Then I got a playstation and never really looked at the computer again except for the net. :-[ I can follow a DIY and solder whatever, but I lack the knowledge to create my own work in this field, I can only copy others. I saw the arduino in a magazine and owned one 2 days later, and now here I am, wanting an entire education as an electrical engineer :)

Your own earlier mention of the crankshaft sensor is digital if all you know is when the crankshaft is at the top position (it outputs HIGH) and else your somewhere else (it outputs LOW). To make use of it, your Arduiino code would look - very often - at the pin-value and do something (f.eks. add one to a counter to count number of revolutions) when it turned HIGH.

The crankshaft position sensor works a little different than that, depending on manufacturer. For Instance lots of Hondas use a TDC sensor to do what you are describing, and a crank or cam position sensor that can have as many as 30 triggers (one in each tooth of a cam gear for instance) to determine actual position at any given moment. As the engine speed increases, the length of the pulses gets shorter because the time between each trigger is decreasing. Would this be an example of PWM?

The analog values from the analog input pins is limited to detecting 1024 distinct voltage levels. It is the way the circuit is constructed. So whatever the voltage is (between 0 and Vref/5V), the analogRead() will give you the nearest 1024th value. You would have to know what the voltage measured, to give the number (f.ex) "734" meaning - it might mean 80 degrees (temperature sensor) or 57 Tons (pressure sensor). On your RC controller it probably represents how much the stick is pushed. As the number only can positive, one usually offsets: 0-1023 means -511 to +512 (as an example)

Because the signals im using are running through the transistor bridge, when I watched the serial of the analog input (that was my first sketch, the one posted was what it became) The numbers would hover around 200-400 on both pairs (FM & BM) (LM &RM). When a button was pressed from one of these pairs, one signal would drop to 0 and one would go to about 670. I assumed this was because the transistors were bleeding through a small amount of current at all times until the button was pressed and it gated closed the other input. I may also be completely wrong.

As a minor side issue, when you call Serial.print, the Arduino does nothing else in your sketch whilst the Serial is printing, ie. it will not loop through checking the other pinvalues. (There are ways around this, but requires far more explanation) It will not matter to most programs, but keep your prints short, and/or set a high baudrate.

Great information. Thank you.

Oh, and while you're fooling around with your little RC-toy, it might well be that those behave like standard RC Hobby Servos. In that case, the position of the servo (or the RC electronic speed control) depends on how lon the signal is turned on (usually 1.5 ms every 20 ms means middle, 1ms minimum, 2ms maximum). If you see that kind of signal, the Servo library is the way to go for this kind of work.

Another good thing to remember which can confuse people, is that while the Arduino can convert analogue inputs between 0 and 5V to values between 0 and 1024, it can't produce any analogue output. The things labelled analogWrite is in reality a PWM signal of 500Hz (cycles, you probably got that already) where the length the time of the 5V state is varied. When attaching a LED to such an output, the LED becomes dimmer or brighter as you vary the value.

Oh, and then to make your confusion perfect, there are out there many other clever schemes to send data around as digital values which in the end will do things, like I2C, SPI, PWM, PPM and other, which are directly implemented in the receiving IC. What I mean by this is that something looking deceptively simple from the outside might actually be a lot more complicated. This can be be really tough when trying to understand basics and stumbling across those. A picture of the electronics of your RC car might really help pointing you in the right direction. Also, if you have an oscilloscope available, look at the values of the signals you mess around with. It might give you clues about what you're really dealing with.

Korman

It is only a coincidence that the max value of analogWrite(), 255, is also the variable value of HIGH. Because an 8-bit byte can represent a maximum numeric value of 255 (2 to the 8th power) They could have just as easily implemented a 10 bit PWM which would have used values from 0 to 1023.

More understanding dawns on me. I have learned more "applicable" information from this thread than several hours of "book" time ;D

You really need something like an oscilloscope to "scope out" the output of your mystery chip. Or else draw out the circuit schematic diagram to give you a clue what kind of signals you are looking at. There are relatively inexpensive oscilloscope converter boxes that plug into your computer USB port. Something like that would be invaluable here.

I don't really care about this chip in particular, I am just learning from hands on and then the question/answer. I know a lot of my questions are technically getting off arduino, but I don't know of any other forums where I can ask questions of electrical engineers :'(

I have had a love affair with cheap R/C cars for a long time because I was never able to have one as a child. So whenever Im at a chain store at an after Christmas sale and I see one or two left of a model marked down 70% I just buy one. I started taking apart a second car today. Its an "AlienRacer" car I got for $20. It has many more features. It has tank drive instead of front steering via tricky gearing. It also has a 3rd motor that makes the top open up to make an alien pop out. Whats more, the transmitter has a little speaker in it and a couple buttons trigger sound effects, so there is a lot of knowledge to be gleaned from it.

Another good thing to remember which can confuse people, is that while the Arduino can convert analogue inputs between 0 and 5V to values between 0 and 1024, it can't produce any analogue output. The things labelled analogWrite is in reality a PWM signal of 500Hz (cycles, you probably got that already) where the length the time of the 5V state is varied. When attaching a LED to such an output, the LED becomes dimmer or brighter as you vary the value.

This information was very helpful. The following part went right over my head! :-?

Here is what I would like to do next. I am wondering if it is possible to amplify the 49mhz signal using an op amp like the 741 or the lm386. I mention these two in particular, because I have them. If they are bad choices, what is a good choice? I do not wish to search for this, because I am afraid I will find a schematic, which will defeat the purpose of this exercise, which is to force me to spend some more time with my IC textbook. With no "project" to apply the information to, I find it about as exciting as watching paint dry. I ask what may be a good choice because when I finally do start to understand how such a thing might be wired up, I would like to have the necessary amp on hand.

I am wondering if it is possible to amplify the 49mhz signal using an op amp

Here's where you need to get more specific. Why do you want to amplify the signal? What do you expect to gain from doing so?

I am wondering if it is possible to amplify the 49mhz signal using an op amp like the 741 or the lm386.

Well if it was 49mhz then yes but as it is 49MHz then no. (49mhz is 0.049 Hz which is very low)

Not only would that IC not cope it would be illegal.

It is only a free to use band it is not a band where you can build or modify your own transmitters. All transmitters sold must be "type approved" which means the design must have been tested in an approved test house. This costs thousands (insert your currency of choice here).

Here's where you need to get more specific. Why do you want to amplify the signal? What do you expect to gain from doing so?

With my toy powered from the arduino instead of the 12V it was made for, the range is only maybe 5 meters. I wanted to expand this range to the original 10-15 meters. I noticed I can up the range by using a separate 12v power supply for the toys pcb. If the goal was to simply increase the range, I could do it with an external 12v, but I was hoping it could be done digitally so I would have a defined goal (increasing range) that would also teach me about basic (8 pins seems about as basic as they get) ICs.

Well if it was 49mhz then yes but as it is 49MHz then no. (49mhz is 0.049 Hz which is very low)

Not only would that IC not cope it would be illegal.

It is only a free to use band it is not a band where you can build or modify your own transmitters. All transmitters sold must be "type approved" which means the design must have been tested in an approved test house. This costs thousands (insert your currency of choice here).

Well since you are saying its not actually possible, its a moot point, but I am not actually worried about any legal issues. This is all strictly for learning and I am in the part of the US that is dominated by livestock and not people. If even discussing things that can be illegal is not allowed, apologies, and I will not mention it again.

Technically, if you aren't trying to figure out how to connect something to an Arduino, the discussion is off-topic here in the Hardware/Interfacing forum. It is probably the kind of discussion that was meant for the (mis-named, IMHO) "Frequently-Asked Questions -- For issues that don't fit in any other board." I am only stating this because I feel guilty continuing this discussion here as it appears to be off-topic.

I understand your concern, I actually started my first threads in the FAQ section (after finding there was no 'newbie' section and determining that FAQ was the closest thing) but received no worthwhile responses. I assumed this was because the 'regulars' don't really check FAQ very often. Then I read threads in other sections, identified where the highest concentration of people who know way more than I do were, and thats why my thread is posted in this section :-X If there is a non arduino forum that would be better for asking questions like this, I am more than willing, just uninformed (as to what forums those are.)

Typically it is recommended to start with an Arduino and go through all the basic steps and build more complex understanding on the foundation of the simple stuff. Are you going through this exercise with some end-point (a specific project) in mind? Or is this just for general edification?

I find I do not learn very well from doing it this way. I much prefer a Socrates method of having a question/problem for me that I must then work out. I retain much more this way.

I'll level with you. I hate even mentioning this because i dislike using such information as a 'crutch' and also because just typing it makes me very sad. My mother, with whom I was extremely close, passed away unexpectedly ten days ago. I have a pretty active brain, and it wants to dwell. The only thing that seems to help is to completely throw myself into some new (uncharted for me) waters where most of my brain power thus becomes occupied. Thats the reason for my zeal.

As for a "project" I would eventually like to end up with something R/C controlled that serves some utility. Perhaps an R/C lawn mower like in Make issue 22.(I could copy this project completely but by doing so would gain very little actual knowledge of how parts are working) Or maybe an R/C tool creeper so when I leave this or that tool 3 feet out of reach when im under a car, I can order it to me.

I realize my next order of business is to just purchase a dedicated reciever/transmitter, and now would like suggestions. Price point is a large factor. Ideally I would like to spend less than $100 on said pieces. Since this is back to interfacing with the arduino, is there a specific model or brand that can be recommended? I don't get to travel abroad and would have no need of the separate settings for region like in the set you purchased. If I could save money by getting something without these features, I would, but I also dont want to spend less money and end up with garbage.

Thanks as always.