So yes it can.
And you have a good name.
Fusion Control Centre
I am looking at having a "System Monitor" screen in my RoadRunner application.
What i am looking to do is have this screen show:
-Vehicle +12v voltage
-Total amperage being drawn from system
-Amperage draw from each amp (2) and possibly the car-pc
-Temperature of each amplifier
The display would have each variable shown as a dial, with the number shown inside the dial under the needle (a lot like most motorcycle speedos)
What i am wondering is if the fusion brain can give me this kind of information that i can translate into roadrunner.
1-The vehicle voltage info seems to be obtained from a voltage divider. Is there optimal resistance for the two resistors that i would use for this?
2-I understand there is an amp-meter made for the fusion brain. However, i need one that will work with 4ga wiring (the one that is shown looks like it will accept appx. 12ga wire).
Does the fusionbrain amp meter shunt cause a voltage drop to my amplifiers. From what i have read, it is basically a very low value resistor. If so, how much of a drop will my amps get? My vehicle currently runs at 14.8 when running 12.5 when on battery.
3-Also, my two amps are fused for 50A (sub/amp) and 60A(4ch)..would the 50A amperage shunt be ok for that? (My amps have never blown a fuse btw)
4-As fas as temperature,i would get two of the temperature sensors (one for each amp) to show an individual read. Do those sensors have a D Shape to them? They seem to be cylindrical on the fusionbrain site..I would need a flat area to adhere it to the case of the amp with some thermal paste.
Does this sound achievable?
Hopefully i can get some better understand of the logistics of this whole thing so i can get the ball rolling on adding the fusion brain to the car-pc.
So yes it can.
And you have a good name.
Fusion Control Centre
Fusion Brain Version 6 Released!
1.9in x 2.9in -- 47mm x 73mm
30 Digital Outputs -- Directly drive a relay
15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
Buy now in the MP3Car.com Store
my rr plugin "rrfusion" will display sensor data in both raw and converted values as labels in RR. Check the RR plugins subforum for it and try it out.
A couple of things come to mind using a current shunt.
First, if you have 50mV full scale into a 5V ADC for example, you need to look at the number of bits the ADC has to see if you've got the resolution you need. With a 50mV = 150A shunt, you've got 1/3mV per Amp so 1A = .0003333V, 2A = .0006666V, etc. So, used directly, most of the bits of your ADC reading will be zero. You might have to amplify the current shunt voltage to get more volts/amp.
I'm not a current shunt expert, but I've read that you don't really want to use one close to its rated capacity continuously because its basically a resistor and heats up. The number I recall is something like don't use it for more than 60% of the maximum rating on a continuous basis. I don't know enough about car audio amps to say the 50A shunt would have issues there.
Another consideration is where you put the shunt in the circuit. The ADC probably reads voltages referenced to its ground. If you put the shunt in the + wire, you have a voltage reading of 0-50mv except its 12V offset or so from ground. I don't think the Fusion Brain ADC will work with that. You could put the shunt in the ground lead, but now you've introduced a small voltage between the battery ground and whatever you're powering. Now that ground isn't really the same ground the rest of your system uses so you can get ground loops. If the negative power lead into the amps is grounded to the car chassis through any path (like your PC sound outputs), you've now got all kinds of issues including the fact that some of the amp current probably isn't going to flow through the shunt so the readings are off - maybe way off. There are circuits that allow you to use the chunt in the + lead, but it requires some electronic design and fabrication.
As already suggested some of the Hall-effect sensors that aren't directly connected to the wire carrying the current eliminate some of these problems. They have drawbacks too though: like cost, they need a power supply, and also a bit of circuitry to convert their output to a voltage. I've also heard that some inexpensive brands have some type of memory effect that affects their accuracy if you use them near their maximum ratings too.
After reading the info you guys have given me, i have gathered this (Let me know if im right)
The 50mv output from the shunt may be too low for the fusion brain to pick up, or notice the .000xxv changes. Can a hardware developer of the FB let me know if it is sensitive enough.
They also offer a 100mv versions too..i imagine that one would give me a more accurate read.
With your math of 50mv 150A shunt saying that for each Amp i am getting 1/3 mV. So, would that mean with a 100mv 150A shunt i would get 2/3mV for each Amp?
...figuring you are going by amperage rating divided by milliamp rating
Translating into 1A = 0.0006666V / 2A = 0.0013332/ 10A = 0.0066666
I agree with what was said about the shunt rating...I have also read about only using a shunt to 2/3 its rated power. The site i listed above states that as well.
My sub amp is rated for 50A (fuse rating...it never draws that much)
My 4ch amp is rated for 60A (fuse rating...it never draws that much)
I am aiming to get atleast a 100A rated shunt.
Next, as far as placement i would be placing it on the +12v power wire right before each amplifier, after my distro block.
As far as the voltage..could i use a voltage divider (as discussed earlier about getting vehicle voltage) to get the cars ~12v down to what the fusionbrain will understand? (0-5v)
Or would that mess with the reading from the shunt?
I think the hall-effect way will be too expensive, to bulky, and too time consuming to set up right....i would really rather use an analoge shunt.
Thanks for all the help guys,
You really need a shunt and an op-amp to isolate and scale the voltage.
thanks greenman...did some reading on operational amplifiers.
Drew up this diagram below to show what i belive is how an OP-AMP would be used in my scenario.
Sorry for all the confusion on this guys, new to alot of this.
I appreciate all the help :-D
V+ and V- would be directly connected to the shunts 50 or 100mv output.
Vs+ to the positive side of the power supply
Vs- to the negative side of the power supply
Ground to ground
and Vout to one of the analog inputs into the fusion brain.
As far as obtaining an OP-AMP radioshack shows they sell two models
a TL082/TL082CP Wide Dual JFET Input Op Amp (8-Pin DIP)
and a LM741CN Operational Amplifier (8-Pin Dip)
would either of these work for the application i am using them in? I am not sure how to get one that will work on either regulated or unregulated 12v (for the power supply) and how to figure if it gives me the right ouput (0-5v) for the fusion brain.
close. You're getting there. I'm impressed you;re reading up on op amps.
You need some resistors with the op amp to set the gain. go read the wiki on it
I did...and i think it is way over my head of electrical engineering lol. Im self taught with alot of this stuff.
Let me take another look at the wiki..i think i can decipher it...