High Amperage Circut

Ok, I see what you are saying there now. it was a very late night when I posetd that. An apparently, there were a few things that I forgot to mention.

I am trying to figure out a way for the arduino to "read" that line to do the continuity check. Would it be possible to do an analog read on that line somewhere to see if the line is going to ground?

I could put an LED or something in there that could light up if good, but i want the arduino to be able to capture it.

I will have to look into that. I dont even know what they are used for, yet.

Looks like it is time to delve into a new component =)

You make it sound so simple =).

Would you have an opto-isolator to reccomend in this application? There seem to be many different types. I am looking at Digikey, and there are quite a few types of them. I am currently looking at "Optoisolators - Transistor, Photovoltaic Output". That seem right to you?

If I understand correctly, the photo transistor will be triggered by the led. This should work just like a base current on a regular transistor? Which measurements are important to me on the opto-isolator?

All along the way, I have been trying to do the math as I go, and I am not sure where to start on this one. I do know the resistance igniter side. Will the opto-isolator introduce more resistance?

Thanks.

Would the opto-isolator needs it's own battery? Does it need to have a different ground?


I am looking at this image , and all that I see seem to have their own power sources without common ground.

OK, that makes sense. I will try to get that built into my circuit. Are the stats not important here? I am not seeing any specs. I did see a datasheet here Siemens IL1 datasheet pdf

I like your idea about putting the LED and the Opto-isolator in there. That will be incorporated into the design. I might put up another schematic with that added when I get home.

A question about the common ground though. If I use the same battery pack as the launching part of the circuit, wont they be sharing the same ground?

I am going to look into ordering those now.

As a side note, I printed my first Circuit Board this weekend with the toner transfer method. I got a little too hasty and used too big of a drill bit on the pads, and ended up wrecking it. Also, it was a Tiny board (1/4 X 1 1/2 inches), so ironing it was a bear. I imagine with a larger board, the ironing will be easier since I can hold it in place as I iron it.

I was able to "save it" by soldering wires to the traces that mattered. I can now get axis data off of a wii nunchuck =). All in all it was exciting, but I will probably end up just purchasing what I was trying to build WiiChuck Adapter - DEV-09281 - SparkFun Electronics.

I have been looking at that site, and I like it. They have good prices on stuff there. I may even order some LCD's and such there. They seem to be similar to what is on sparkfun, and adafruit at half to a third of the price. I will just have to see if they work the same.

Very cool!

OK now about the opto-isolator, in that PDF, I see that there are 6 pins

1)anode
2)cathode
3)NC
4)emitter
5)collector
6)base

anode and cathode are the LED, collector and emitter are just like a normal transistor. What about the base, how is it hooked up? how does that work into this equation? I thought that the base was being handled internally by the receiver.

Stuck at work =(. I hope to have a modified schematic up before I got to bed tongiht.

I used some cheap photo paper from my local grocery store. It can in 4X6 cards, and it was cheap. There seems to be some impressive research out there on what type of paper to use and one guy had ALOT of information. I started here and there is a link http://gilmore2.chem.northwestern.edu/projects/garbz2_prj.php to an article that had much more information by Thomas Gootee, but the link seems to be dead now.

He mentioned a certain kind of Staples photo paper, but I was not able to make a trip out there.

I had heard about magazine paper (and promptly forgot about it), and I think that I am going to try that next time. I did notice that my photo paper had a pretty thick coating on the front and back which did not dissolve when soaking in the water (part of the problem I had). This made it peel off some of the toner when I peeled off the paper. I think that the magazine paper, which is both thinner and does not have that same thick coating will work better. Thanks from bringing that back to my attention. The good news is that a black sharpie permanent marker worked in places that the toner was pulled off.

About the opto-isolator.

So the base will not be hooked up, the collector will be on an arduino pin, and the emitter will go to ground?

Do I need to use a digital or analog pin? Does it matter? (I am assuming they will both go to zero on success so digital might be good)

Do I need to add another resistor in series with the collector? I have been assuming not, if it is going to ground.

Ok, so now I need to do some math. I am trying to figure out what R4 should actually be.

Now that I have added the opto-isolator and the led into the circut, the math has changed and I need to check myself. This is where the numbers matter. I need to make sure that I do not pas more than 50mA to the match in the "testing"/"continuity" mode. Also I want to make sure that the reverse voltage on the LED will not burn it out.

When RLY1 is triggered, it will send the "full" voltage from the battery. Only, it is no longer the full voltage, right? The LED's (both of them) will drop a predetermined amount of voltage. To calculate the new amperage at the igniter I am trying to calculate it as:

(Base Voltage - Voltage Drop from LED's)/resistance(in Ohms). is that correct?

I need to figure out what the voltage drop will be. I am finding 1.7V for an average Red LED (not sure if that is right). Just hazarding a guess, double it = 3.4V

(5V- 3.4V) / 331 Ohm = about 4.8 mA.

ok, brain fart. I just broke out the volt meter and attached one lead to each side of the powered led and measured 2.03V. That should be the voltage drop for this specific LED.

what can I assume for the opto-isolator? Less?

I had a problem that kept me from ordering those opto-isolators. Do you think that these would work as well?

http://cgi.ebay.com/10-pcs-H11G2-Opto-Isolator-/130362906356?pt=LH_DefaultDomain_0&hash=item1e5a3c16f4

or this one?

http://cgi.ebay.com/10-pcs-H11AA1-Opto-Isolator-base-connection-AC-Input-/130362913456?pt=LH_DefaultDomain_0&hash=item1e5a3c32b0

gotcha, thanks. I ordered the H11G2 set just little bit ago. I will post more infomration after I get them and hook them up.

Here is the latest picture of my circut, if you are interested. I do not know what R4 is actually going to have to be until I get the optp-isolator and LED up and measured.

No, I am powering the Arduino off of a 9V Battery, separate from the ignition power source. I just have them coming off as 5V because the signals are coming off of digital pins. I did not know of a better way to represent them in my circut design. This is actually a screen cap from a simulator, so I can turn the switches off and on to see the results.

My next phase of development is going to require a bluetooth module. Do you have any reccomendations? I have been looking at this one Bluetooth Modem - BlueSMiRF Gold (Old-School) - WRL-00582 - SparkFun Electronics, but I do not know if I need to spend that much $$. I have seen some that are cheaper, but seem to be MUCH more complicated. I am willing to spend a tad more $$ if it makes this system easier to build. 20-60bucks is not that much of a difference at this stage of the game. I have already invested enough time and money into this project =)

I was going to use WiFi, but the android phone OS (the intended interface for this device) is not able to connect to ad-hoc networks, and I do not want to have to lug around a wireless router.

  1. It looks like RL2 does not have a protection diode across the coil (like D1 across RL1)

Oops, that is a mistake. I forgot, again, to put that in there. It is now added.

I believe that I have now ordered the rest of the parts that I will require for this device. YAY!

I have purchased the opto-isolators above.

An enclosure for the device:

An LCD Screen:

A Bluetooth Module (Ouch)

And a WiiChuck Adapter
WiiChuck Adapter - DEV-09281 - SparkFun Electronics . I made one of these, but it came out very ugly. I figure for 2 bucks, why not. It did not increase my S/H at all =).

I will be putting things together as soon as I get the rest of the parts in the mail. Very Exciting!

This device is going to be wirelessly controlled from my andriod phone. I had not talked about it since the beginning, and I was looking for reccomendations a few posts above. It seems like that bluetooth module is one of the easiest to use, so I went ahead and picked it up. This way the device can sit by the launch pad and have shorter wires. Then I will initiate the launch from anywhere in bluetooth range. I have a few other ideas for the bluetooth module too.

I was originally talking about using WiFi over bluetooth, but there are drawbacks to Android and Wifi on the arduino. Namely, the Andriod OS is unable to connect to an ad-hoc WiFi network without being rooted. IF I went this way, I would have to also carry around an external router or something similar.

I have a few ideas for networked RFID readers when I buy a house (cannot do it now in my apartment) for access control. It might not be practical or secure to create my own access control solution, but maybe I can use it for my garage if I am not sure of the security. I will have to measure the security of it later. If I do get into this, I will want to network these readers over ethernet or wireless(most likely), or other wired techonolgies (RS485?) to a central location that controls which rfid tags have access.

The WiiChuck adapter is just for general use. I created my own a little while ago (when I was talking about the toner transfer pcb I attempted), and it worked, it just is a tad ugly (I ended up having to solder wires to it because I could not use headers. I just put it in there because I thought it was cool. It will be used later to wirelessly control a robot (rover type).

Good point. It would be easy enough to make this a wired device. I have plenty of other uses for the bluetooth module.