Regulating a 12v DC Power Source
Im Talking about a car battery, im wondering number one will the stamp consume enough energy to kill my battery, and where or how can i build a regulator to regulate it to a safe operating voltage>? basically im taking a RFID reader and taking the Clutch Saftey switch and plugging a relay between it, basically what the switch does is wait for the clutch to be pushed in then it will allow the starter to turn the car over, im going to by pass it either with a relay or a transistor, i need to operate off the battery or carryalot of nine volts with me lol, im going to be using the Homework board for this project, at least for now some of the porlbmes i have thought of are
How will the microcontroller no to disconnect the switch? once i use the RFID reader it will click over to allow the car to be started, should i use a timer? like pause 30000? then by that time i should have my car started and it will go into low power mode and wake up every 2 seconds to check for input, if i use the battery i should be able to leave it powered constantly, Just leave some comments tell me what you guys think about the idea and some possible problems, and solutions! thanks guys
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
How will the microcontroller no to disconnect the switch? once i use the RFID reader it will click over to allow the car to be started, should i use a timer? like pause 30000? then by that time i should have my car started and it will go into low power mode and wake up every 2 seconds to check for input, if i use the battery i should be able to leave it powered constantly, Just leave some comments tell me what you guys think about the idea and some possible problems, and solutions! thanks guys
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
Comments
Yes
and where or how can i build a regulator to regulate it to a safe operating voltage?
Get an LM317 for voltage regulation,·look on line, there are easy calculators to tell you which 3 resistors to use and how to connect it.
Just leave some comments tell me what you guys think about the idea and some possible problems, and solutions! thanks guys
Sorry, I don't undersatnd what your project will do???
You'll need only 2 resistors not 3. You may or may not need the 2 capacitors, they're there only to filter some of the high frequency noise from the DC lines. The capacitor with the + sign is the type shaped like a cylinder. The one without the + sign is the flat round kind.
I don't know if the caps are 100% needed for your ap with the car.
I get it now, your project prevents a car from starting without your RFID tag close by, right? Cool, please let me know how your project works out, sounds like a good idea.
Is there a recomended fuse rating?
I'm the FNG, this is a fun forum.
No RFID Swipe-> Turn Key to Start Car-> No Start
RFID Recognized Swipe->Turn Key to Start Car-> Transistor/Relay allows the two wire switch to ground out-> Starter Turns Over
will a transistor work for this project do you guys think? i have one side going to the collector the other end going to the emmitter and base going to the stamp? since i knew relays have a life span transistors work forever to my knowledge unless you smoke em.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
You might want a separate 5V regulator for the RFID reader, a low drop-out regulator designed for use in automobiles (look at the datasheet where it will say this), one with a separate on/off pin that you control from the Stamp. That way, you can turn off everything but the Stamp and the Stamp itself can go to sleep most of the time to reduce the current requirements even further.
It's probably not necessary, but a useful exercise in saving power.
Post Edited (Mike Green) : 9/8/2006 8:55:20 PM GMT
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
i dont think you read what im doing man, Im using the clutch safety switch to be able to diable the start, the car is a manual and if you have one you know the clutch has to be pushed in for you to use the key to turn the car on. Its a switch under neath the dash board which has current running through one side, when the cars clutch is in the power circuit is completed and the car can start. so what im doing is taking the two wires off of the little switch and putting one side to the collector and one side to the emmiter.... but there is still too much current going trhough the transistor to stop the car from recognizing a connection. Do you get it?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
Post Edit -- I think that this RFID-enabled switch should be in series with (added to) your existing system, not in place of any element (or switch.)· You could use the key to initialize the Stamp (the same way the key turns on the radio if you leave it on.)· So, you'd click it one notch (dashlights, Stamp activating...) and then give it a·second or so and then go ahead and crank the starter, etc.
Post Post Edit --·Whatever you do, make sure that in case life happens, that you can jumper everything out and still make it into work on time.· Does that make sense?
Post Edited (PJ Allen) : 9/9/2006 3:00:56 AM GMT
If(ClutchSwitch = Enabled AND KeyPos = 3)
GoSUB StarterInit
now thats as basic as i can get it, because im not positive on voltage or anything but in my mechanics tech lab i know that most sensors run on logic level because the CPU is just a souped up microcontroller running normally < 1 Volt again, dont hold me on that but looking at the gauge wire its running its nothing more then that, guys for you tech heads its a momentary Switch, like a car horn it just completes the circuit. lol i forgot im not on a mechically inclined website, just electronically inclined! i hope this helps you guys, Help me!
edit:
PJ i would love for the stamp to be powered off the car but its looking kind of tedious to get that voltage down to power the stamp, probably constly too. If i could create the regulator then that would be wonderful, and figure out in my servince manual what wire power i can use when the car turns on, maybe splice into the radio power circuit?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
Post Edited (willthiswork89) : 9/9/2006 3:30:50 AM GMT
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Stephen
if anybody is still confused heres one of my PRICELESS paint schematic/Explanations
·
*so basically its a rouch diagram of what the thing really does, it doesnt complete the circuit to the starter, just tells the ECU its OKAY to power the starter up, basically that there is a human operating the vehicle. in my drawing you will notice its in its Open position meaning the clutch has not touched the button to complete the circuit*
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
Post Edited (willthiswork89) : 9/9/2006 3:56:17 AM GMT
I'm pretty sure I know what your talking about. Your BS can't supply enough current to make a relay work. The fact that you used an equation to try to exlain what you're doing is interesting.
·your sig says -Learn somthing about everything, and Everthing about somthing-
Take some time and look into how a transisitor works, If you understand anything at all it will be well worth your time. You can put a signal on the B of a Q and control large amounts of current.
We all know how frustrating figuring out a project can be. Take a deep breath, and try not to take it out on the folks that are trying to help.
It sounds like you have gotten some good advice here. Firstly, use a relay to switch the power to the car's starting circuit. Use a transistor to drive the relay from the Stamp. If you are using a regular relay (one with a coil) use a diode reversed across the power leads of the relay to prevent voltage spikes from the relay backing up into the stamp. Look up "back EMF" to see what I mean here. If you are using a SS (solid state) relay with < 5V actuation, dont worry about the diode or the transistor. If you use a SS relay with a actuation > 5V use the transistor but forget the diode. In all cases, have at least a 220 ohm resistor in series with the Stamp pin. With a transistor, use a 1k.
As PJ noted, don't simply replace the clutch switch. This is an important piece of safety equipment, both for you and the car. Put the relay in series with the clutch switch. That way BOTH the RFID and the clutch switch will have to be closed in order for the car to run.
Start by getting the Stamp to turn on an LED with a transistor. Figure out how to place the back EMF diode. If you have it wrong, the LED won't light. Then use it to switch a relay. Then use it in your project.
An additional note: Cars can have very noisy electrical systems that can cause problems with the Stamp. If you get it all to work on the bench and then it has problems when installed in the car, that may well be the problem. If so, look up filtering power supplies and come back here with questions.
Good luck!
Jonathan
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
But i DO NOT want to control the STARTER DIRECTLY, i want to control the sensor on the car which tells the ECU to allow voltage to the RELAY in the car itsselft to start the starter.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
There's no "sensoring" going on, here, no 5V.· It's all system/battery voltage.
(see pic attached)
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
The relay, he wrote, NOT the bloody motor.
Post Edit -- The 78ST105 is available from DigiKey, their PN is PT78ST105V-ND· http://focus.ti.com/lit/ds/slts059a/slts059a.pdf
You can use it as a voltage regulator, but -- it can, given improper handling, be made into a finger-burner or a cigar lighter.
Post Edited (PJ Allen) : 9/9/2006 10:19:00 PM GMT
The LM2931-5.0 originally from National Semiconductor is similar, with similar current output and also designed for automotive use.
I'd stay away from the LM117 if possible. It uses more idle current, requires adjustment resistors, and isn't specifically designed for the voltage surges common in an automobile's electrical system.
Either the MIC2950 or the LM2931 would work nicely here. Be sure to have an appropriate sized fuse between your box and probably the accessory power switch on the ignition keyswitch. That way, your box is only turned on when the key is turned to the first position. Check your car's manual for the best place to connect in. You want your box to be on in both the first and start positions of the switch.
Post Edited (Mike Green) : 9/9/2006 10:04:57 PM GMT
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
You can use one regulator BUT MAKE SURE THAT YOU USE A HEAT SINK because when you run the card reader and the stamp
you will be drawing about 110 mil amps
Now that make the regulator·run very warm
Now if you run Stamp on one regulator and Card Reader on other regulator then you do not a heat sink and i have used the UN2803
now this very easy·(and i also put a regulator on Un2803)
·If you need more than 20 mil amps then you can tie more than one InPut together and more than and more than one OutPut together to get more current i tie 3 of them together and work with getting warm
Regulator do not cost very much and i use one every device that i use
In one porject that i just did i had a relay that used 80 mil amps of current·i just used the UN2803 that Parallax sells in just that way
Now if the safety has 5 volts·on ·that switch then the cars controler uses that to sence the switch and unless you make it see the same
volts then you might see a Failure or damage the controler on your car
Now if i where doing this i would use the relay coil for the starter· but that just me and that my 2 cents worth which may not be worth much
I hope this help you
Sam
FOr simplicity im using the Saftey switch since
A. The saftey switch needs to be bridged to even start the car because the boot that presses on it is messed up
B. The micricontroller just needs to control a 20MA Reed Relay to connect it like that switch would do so no damage to the sensor since its just doing what the switch did.
Again when the car started the power to the stamp will be disabled since it takes everything the car has to turn on and will disable the microcontroller which will disable my reed relay which in turn will interupt the car from starting,. Thats hte problem im facing and not sure how to compensate for that besides just using a NINE VOLT to control the microcontroller. so update to question
Question:
What can i do to power the stamp since when the car turns over the power is cut from everything except the starter?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
theres my baby [noparse]:)[/noparse] this is the test subject haha it has been for various things. so anyways ill begin looking up the service manual for the 92 lude and if you guys could answer my question for if the regulators can be bought at readioshack ide be happy!
Edit** I Found these at radioshack
http://www.radioshack.com/product/index.jsp?productId=2062599&cp=&origkw=regulator&kw=regulator&parentPage=search
can someone explain them to me a little in detail?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
-Learn somthing about everything, and Everthing about somthing-
Post Edited (willthiswork89) : 9/10/2006 3:22:43 AM GMT
5 volts @ 1 amp output, and have a serious penchant for Internaional rectifiers logic level fets. More like a solid state switch, no biasing, just a pull down resistor.
IRLZ14 will more than handily drive a relay with minimum components, and yes PJ's schematic is dead on.
Just make sure the FET is carrying the same ground as everything else. 7805 supply, and IRLZ14 relay driver from the stamp