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xtremeboomer

Member - Posts: 12

Joined: January 10, 2009

Location: New Hampshire, United States

Posted: April 14, 2009 at 4:26 PM / IP Logged

http://rfidshop.com.hk/active.html

Peek at this, this looked like it may work......input?

KPierson

Platinum - Posts: 3,527

This member consistently provides reliable information

Joined: April 14, 2005

Location: Ohio, United States

Posted: April 14, 2009 at 4:54 PM / IP Logged

OEM systems are active RFID, which means both the car and the fob are battery powered. OEM range isn't that great, but they use multiple antennas to make up for the lower range. OEM systems don't "wake up" until you push the button on the door or lift up on the door handle (depending on make/model). The actual keyfob itself (generally) communicates to the car with RF, not RFID. The entire process works like this:

Driver wakes up system by pushing button on door

Car sends RFID signal to "wake up" keyfob

Keyfob wakes up and sends unlock command

Car unlocks doors

Going this route will greatly increase the complexity of the system and I doubt you'll get the help you need for such a project on this site. There are products out there that allow passive entry, but I have yet to see one that allows passive entry and pushbutton start.

The systems you linked to may work, but I'm guessing they will require quite a bit of power (to get the range they claim). They are most likely designed to be connected to 120vac. You may want to contact the company and see what they got - they may have something.

xtremeboomer wrote:

I honestly wasn't sure what RFID unit to get, or its range, I figured it was at least 15 feet as the RFID units in some newer cars works around that range and are used for proximity unlocking, and locking would seem just as logical with the use of relays or what not. My thought was having the unlock command trip a timer for the RFID that is linked to the acc/ign wires and the RFID remains on until the lock is activated or the key left the range, which I was assuming was beyond the car itself so it wouldnt power itself off while driving. However thinking about how batteries can get low, it probably isn't a good idea to have the system turn off when the RFID tag gets out of range, but turning off when the doors are locked seemed to make sense to me. Problem is since I want the RFID to work as my key and the acc/ign wires, the RFID unit cannot turn off, unless the RFID triggered a relay(?) that remained on? This is honestly the technicals that confuse me so this is where the help comes in alot. Assuming the RFID only has the range you are talking about then I would want to install the antenna under or near the drivers seat so it can read the fob in my pocket, or if they made a credit card style something I could put in my wallet.

Kevin Pierson

xtremeboomer

Member - Posts: 12

Joined: January 10, 2009

Location: New Hampshire, United States

Posted: April 14, 2009 at 5:59 PM / IP Logged

I sent an emai l but its a hong kongish company so who knows how good the response will be. My thought was it has a buzzer that confirms a link, I thought maybe I could have that buzzer link to a relay or a curcuit of some kind that keeps the acc/ign on......maybe im going in the wrong direction though......

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for schematics, more for build

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