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181  Forum 2005-2010 (read only) / Troubleshooting / Re: Relay Problem on: October 30, 2009, 06:52:11 pm
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Resistance is 45ohm

Yeah... that's not good. 5V / 45 ohms = 111ma which is far in excess of the 40ma you are allowed to draw off of an arduino pin.

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I went to see an electromechanic teacher that told me to use a PN2222A transistor with a 1000k resistance on the output pin.He told me to plug the resistor other's end to midde pin(base),negative side of the relay on one side and ground to the other side(bypass diode included a always) stil I get some weird results,either the relay goes on forever a soon as I plug it or it never goes on....

This teacher told you do... what now? ... I can't quite figure out what that's supposed to do. What you really want to do is hook up +5V from the power supply to the relay. Hook the base of the transistor up to an arduino pin with a 1K resistor in between. Hook the emitter up to ground. Hook the common up to the other side of the relay. Hook up your diode. Now when you give the transistor +5V output from the arduino it will take 5 / 1000 = 5ma. The gain of the transistor appears to be maybe about 60 at that point so your max load would be 60 * 5 = 300ma. That's over what you actually need so the transistor will be saturated which is what you want.
182  Forum 2005-2010 (read only) / Troubleshooting / Re: Relay Problem on: October 30, 2009, 04:38:40 pm
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Problem is;
When I played with my relay before,they worked perfectly!

Have you tried hooking the relay directly up to the(a) power source? What happens? Be sure to only hook the relay up to a power source of the proper voltage. In other words, don't go hooking up a 5V relay to a 12V source to test it.

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Now they can't even activate when the output pin goes up.
I got a LED working fine on that same exact pin.
Also checked the voltage using a resistor from that pin to ground and I get 4.7V wich is enough for the relay but still he ain't working

WhenI plug it in,the voltage I read is basicly 0. (I'd like to say once again; it was working before (before mean alone,relay only with nothing else)and now it's not(keypad is wired and a piezo,both are off while the relay should activate.

Hmm... That doesn't sound too good.

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I tried using a transistor but my lack of skills in electronics showed me pretty quickly how bad I was  :-/

If your relay could take more than 40ma when active then it might have damaged the output. If you can at all help it you want to use transistors for just about anything you hope to turn on/off with the arduino. I know, it might sound silly to go arduino -> transistor -> relay but it's for the best.

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Does anyone has a simple bit of explanation on what would cause that and how to fix it?

Also, if you directly hooked up a relay to the output of the arduino and had no reverse bias diode then you must go directly to electrical engineer jail. Do not pass GO. Do not collect $200. Relays have a bad habit of having something I'd like to call "inductive kickback." You charge it up with 5V and when you quit giving it power it gets lonely and kicks you back at 100V for a couple of microseconds. It's bye bye output pin then.

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Also,
2 days ago I touched the chip by notlooking where I putted my fingers (FTDI chip) and the arduino pin13 started blinking non stop even after a reset and kept on going until I got a usb cable in to reload program and now it's fine,maybe I burnt something?

Well it does not sound like you did it any favors but if you were able to save it afterwards then hopefully it'll last for a while yet. Sometimes you can damage things but not enough to totally fry it. Just enough to mess it up a bit and drastically shorten it's useful life. Things happen... That's why butterfingered people like me have 1. anti-static mats and straps 2. spares

To sum up this whole thing:

USE TRANSISTORS. If you don't know how then look it up. There's help all over the Internet. Or, if you've got some specific transistors laying around then tell us what they are and I or someone else will help you use what you have. Also, get properly rated diodes. They've got to be rated to take a reasonably large surge voltage (although with a diode in there the surge will never get anywhere near as bad as it would have been without) If you are running at 5V then 100V diodes would be fine. They're really easy to get.
183  Forum 2005-2010 (read only) / Troubleshooting / Re: Capacitor circuit issue on: September 30, 2009, 06:16:03 am
Yeah, the joys of CRT TVs... You can die doing that though smiley-sad Be sure to stand barefoot in a pool of salt water when you are feeling around the scan coils. It really helps.

My dad tells a story of a kid he went to school with whose father was a TV repair man. The kid got a HV cap from his dad's stuff and would charge it up before school. Then he'd place the fully charged cap in his pocket all wrapped up. At school he'd volunteer to go up to the board and when another student would be up there too he'd sneak the thing out of his pocket, lean in a bit and touch a leg of the cap to the metal shelf at the bottom of the chalk board. 'twould zap the snot out of the other kid at the board. He eventually got caught when the capacitor melted to the metal shelf. Sounds like a great (if somewhat dangerous) prank.
184  Forum 2005-2010 (read only) / Troubleshooting / Re: BT range insufficient on: March 05, 2009, 01:21:02 pm
The maximum rated range of wireless devices is a really shakey number. You should trust used car salesman more than that number. I've heard a general rule of thumb that bluetooth doesn't normally work at ranges higher than 10M. Heck, I've seen bluetooth headsets for cellphones that have trouble receiving at 2m. There are tons of factors that influence the signal range so it's impossible to say how far is too far.

My guess is that you really want to be using a zigbee device instead of bluetooth. It's range is generally better.
185  Forum 2005-2010 (read only) / Troubleshooting / Re: Using the tx rx pins on Arduino Duemilanove on: February 07, 2009, 11:08:42 pm
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Any chance I could have fried the vdip2 if I tried to use RS232 serial on it?  Geeze, I hope not.  :'(

Yeah, that definitely could fry something. RS232 could be 15-30V and swings AC. Needless to say a TTL (rated 0 to 5v) device is not rated to have 30V negative on an input pin. Nor is it rated to have 30V positive on a pin. Your RS232 serial might only have been 15V but that's still three times the rated voltage of a 5V TTL device.
186  Forum 2005-2010 (read only) / Troubleshooting / Re: Cannot Upload to Freeduino on: January 01, 2009, 10:05:36 pm
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I am seriously considering just adopting a no-bootloader environment and just using an ISP instead of buying another Arduino if I can't get this thing to work.

Well, if you have a working parallel programmer then there is certainly no harm in doing it that way. In fact, it saves you the flash space that the bootloader would have taken up.
187  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino Diecimila not loading sketch!! on: January 01, 2009, 07:43:01 pm
Well, unfortunately it seems like you've probably smoked the board somewhere. The computer will register a connection if the FTDI chip on the arduino is still working (at least for the most part.)

The black chip you are referring to would probably be the 7805 voltage regulator and you board would probably be the diecimila board. That chip is supposed to get somewhat warm but if it got really warm then it means that there was a large current draw on the board. This could be due to a short circuit somewhere or maybe something you had plugged into the board.

A number of bad things might have occurred. If the atmel 168 chip got too low a voltage then it's flash could have gotten corrupted. If the bootloader is corrupted then you won't be able to use the USB interface to upload sketches. You can use a parallel port programmer to do it. Chances are, you don't have one of those. You also could have some other component which is bad.

Depending on how seriously you are into this (as a hobby, a job, a very serious hobby, etc) you really should invest in spare parts. Get some 7805's, some spare caps, resistors. You really also ought to order up more atmel 168 processors. It's best for the hobbyist to order chips already programmed with the bootloader so that you don't have to get special stuff to do it yourself. Though, a programmer can be used to reload the bootloader onto chips you've gotten corrupted so if you are dealing with a number of arduinos then it might be worth it.

In short, I think that you are going to have to assume that your board is damaged in some way.
188  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino Diecimila not loading sketch!! on: December 31, 2008, 10:09:30 pm
It means that something is not working with the link between the arduino and the computer. It could be a lot of things.

How are you sending to the arduino? Usb? FTDI cable?

Is anything else hooked up to digital pins 0 and 1?

Do you have to push the reset button on your type of arduino like board in order to get it to accept a new sketch? ( you do have to do that on some models)

Are you sure you are sending to the right serial port?

Is there something wrong with your cable?

You see.... lots of questions. You need to be extremely specific about your setup and what you've tried in order for people to help you narrow this down. This can be a really annoying problem.
189  Forum 2005-2010 (read only) / Troubleshooting / Re: Fried Arduino BT question on: December 31, 2008, 12:16:40 pm
You could unsolder that and replace it with a new chip. It won't be easy as it's a surface mount chip with very small pins. However, you need to be thorough in checking the other components on the board. It's not certain that the chip in question is the only bad part.

I don't have a BT arduino and I can't see any of the lettering on that chip so I couldn't tell you what it is.
190  Forum 2005-2010 (read only) / Development / Re: Max 232 And arduino/ sanguino schematics on: October 03, 2009, 05:41:42 pm
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Note that this is not a "connection" from VCC to GND; it's a CAPACITOR between VCC and GND.

Oops... Yes, sorry for using such poor terminology.
191  Forum 2005-2010 (read only) / Development / Re: Max 232 And arduino/ sanguino schematics on: October 02, 2009, 09:03:15 pm
Oh, and you asked why a connection from VCC to ground is needed. It's for noise suppression. Digital ICs tend to be noisy and they also tend to send some of that noise back through their power input. With lots of ICs all in the same circuit they can and will send interference to each other. This interference will do strange and hard to diagnose things to the functioning of the circuit. You do not want this at all. This is where our friend the decoupling capacitor comes in. It suppresses the noise on the power pin. In short, use them. You will thank yourself later.
192  Forum 2005-2010 (read only) / Development / Re: Max 232 And arduino/ sanguino schematics on: October 02, 2009, 08:52:35 pm
Westfw's schematic is pretty much how you'd want to hook it up. Except that the schematic uses both of the recieve and transmit lines of the max232. You don't need to do that if all you want is one serial line. The max232 supports two complete serial lines. You just use R1 and T1. On a 9 pin serial line that's pins 2 and 3 (with 5 being the ground.) For simple RS232 serial those are the only three pins that need to be hooked up. This means that in this schematic you'd be using T2 and R1 which is confusing but won't hurt anything.

So if you want one TTL to serial connection then follow that schematic but don't hook up the connections to the DB9 pins 4 and 6.
193  Forum 2005-2010 (read only) / Development / Re: Modify Diecimila to run at 3.3v? on: February 12, 2009, 08:32:28 pm
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What about when plugged into the USB?  isn't that a 5V source?

Yes, USB is 5V so if you want to power a 3.3V board off of it you'd need to use a regulator or a voltage divider.
194  Forum 2005-2010 (read only) / Development / Re: Modify Diecimila to run at 3.3v? on: February 12, 2009, 10:02:21 am
The actual ATMEGA168 chip can easily run at 3.3V but not at 16Mhz. So, the solution is to replace the 16Mhz oscillator with something slower. The chip can run at 1Mhz with it's built in timing circuit (or 128KHz if you want). If that's too slow you might be able to get something else. You really have to look at the Mega168 spec sheet and find a Mhz rating that is fast enough for your needs but will run at 3.3V.

Keep in mind that if you change the Mhz you will also change all of the timings of things. Serial communications will become problematic very easily. I don't know how well the arduino delay functions will work.

I suppose I'd need more information about what you are trying to do  and how fast you need the chip to run to be able to say much of anything concrete.
195  Forum 2005-2010 (read only) / Development / Re: Using diodes to drop voltage on: January 23, 2009, 07:08:20 pm
Yeah, I've had to buy power resistors before (you'd think that industrial workers would be able to understand the concept of a 30% duty cycle on a welder but NOOOOOOO) and I don't really want to do that for this application. For right now I'll hook up an LM317 to get the prototype up and running and in the future I will almost certainly use some form of buck converter to get the voltage down to the proper level.
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