Well all npn work the same in the sense that active they can switch a collector-side load on, and pnp's active can switch an emitter-side load off. (I think I got that the right way round   )

But they all differ in terms of gain and the voltage and current they can handle. A site like this is useful to get sight of the various datasheets.

This site might help, as might this.

could be a blown transistor, relay, connection etc

Here's how to make a simple tester with an LED indicator. About half way down the page it explains how to check out all the ways through a transistor.

You can check the relay simply enough by putting the tester across the outputs while energising the coil.

but now when it hits something it stops and the loop repeats

Not quite sure what you mean there... but yep loop() runs all the time, that's what it's for.

I'm not going to wade through that code to figure it out, but when the bumper switch gets pressed, are you trying to tell it to back out of there? I'd be inclined to back out from an obstacle with a bit of a turn for a short while, maybe a second or so; maybe a random amount of turn and random time?) Then move forward again, hoping this time to miss the obstacle...

Servo city is a good hobby source.

http://www.servocity.com/html/mechanicals___accessories.html

Holy cow... awesome looking place.... I need a supplier like that, but not an online one, one to walk around in and touch stuff 

You should be using a multimeter to make sure that the switches are wired correctly

Especially to get your head around how those 4-pin square pushbutton switches work. If you don't have a meter, at least hook up an LED and a resistor in series with a power source (you could use the Arduino's 5v for that....) , and probe those switch pins with the button pushed and not-pushed, and draw a sketch like the one I posted.

here's a new diagram.

Yeah that looks right, as long as the transistor pins are correct.... Datasheet shows base, collector, emitter, as you have.

Too quick, no base resistor shown.

Ooops, well spotted... It's midnight here, time I turned in.

Here's a really quick and dirty sketch of how it might look....

Yep if the current's not too big, you can take 5v from the Arduino to the high side of the relay as the relay power source I guess.

I'm not trying to be funny, but why don't you just connect it like that example I linked to a few hours back. It's dead simple...

From the high voltage side, hook to the relay. The low side of the relay, to the collector. Diode across those two, backwards (cathode stripe to positive input. Emitter to ground.... Arduino digital pin to the base. Arduino earth and transistor emitter earth one and the same.

As Lefty says, you have no high side connection the relay as it shows in your Fritzing...

Code:

myServo.attach(9, 1050, 1950);

I've never used those min and max parameters in the attach, only ever let them default- wonder if it can have anything to do with those?

Code:

myServo.attach(9);

Is the servo driven from the Arduino's power or does it have its own?- it really ought to have its own, with the grounds joined.

Compare your first lines:

Code:

if (buttonState == LOW);
{

with these ones from the reference page....

Code:

if (pinFiveInput < 500)
{

One important difference!

Funny you should say this Paul:

It's far simpler, though, to use the internal pullup resistors...... HIGH will be not pressed; LOW will be pressed.

I always forget about them, and even as we speak have two buttons with external resistors on my board. I think one of the reasons I forget them, is that I still expect a HIGH from a pushed button, not a not-pushed one. But seeing as I'm working with interrupts, and the attachInterrupt method has a LOW mode but not a HIGH mode (on an Uno anyhow), a pullup makes more sense.

So thanks for reminding me....

So arduino switches on AC power to a PC, PC boots up and has a bat file script run at start-up that loads a serial terminal program and Bob is your uncle. If the PC is already running, have it running the PC go between unio (sp?) PC program that listens on a given comm port and activates a terminal program when commanded to from the arduino sketch, and Jane is your aunt.

I was thinking more along the lines of:

Code:

Serial.startMonitor;

 

The standard de-bounce example didn't work correctly according to the comments in the sketch.  I re-wrote it to actually work:

Thanks John, thought I was going nuts there.