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Car Locator Schematics

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taftech

New Member
I have a few questions about this schematic...
http://www.schematicsforfree.com/misc_circuits/CAR_LOCATOR.GIF


First.. I don't see a power source for the receiver.

Also, the secton of the receiver with the leds, doesn't that need a ground somewhere? I only see one wire going to all of that..

Please, someone look over it and tell me if they think it will work. I am pretty new to making this kind of thing... so I don't really know much about it.

Thanks!
TAF
 

taftech

New Member
anyone?

Can anyone help with this?

What I am actually looking for, is a way to transmit an RF, up to 100 feet or so, and a reciever that only needs to be able to know whether the signal is present or not.

Please help! Thanks
 

Nostrafus

New Member
Neither do I... That's really wierd, the positive is grounded also, hmmm... I think someone screwed the pooch with this one, or made the thing backwards, the negative should normally be grounded... that's really wierd...

Try here...

http://www.electro-tech-online.com/threads/modular-burglar-alarm.49/

and get a walkman, or something, the closer you get to your car, the louder and clearer the signal gets.

Plus you can follow the blinks of the light, however this one doesn't turn on or off via transmitter.

Sorry man, don't know what to tell you.
 

pebe

Member
The transmitter is not the best design but it will work. But from the inductor value shown it will transmit in the long or medium wave broadcast bands, so it will be difficult to detect among all the high-powered stuff being broadcast there.

The receiver will never work - even with the correct power supplies. There is no form of detection - such as a diode - and the 741 is just operating as an amplifier. It could amplify audio frequencies OK but there is no way it can deal with frequencies in the broadcast bands. It was never designed for that.

If you want to make such a device, do a Google search for FM transmitters and receivers. There are plenty of them published.
 

taftech

New Member
Thank you pebe, for analyzing that for me.

What I would really like to have:

A transmitter with a variable switch that could make the transmitting range between 2'-100'.

A small reciever to accept the signal.

Both, operating on a frequency that would not interfere with other electronics.

The transmitter and reciever only need to be very simple, sending only a single signal between them.

Any input would be bery nice.
 

pebe

Member
I can't see mentioned anywhere how this car locator works.
Is the transmitter fitted in the car and switched on at all times when you have parked the car, and you carry the receiver?
 

daviddoria

New Member
correct pebe, that is of course if hes trying to do the same thing that i've been trying to do for months now ;)
 

pebe

Member
daviddoria said:
correct pebe, that is of course if hes trying to do the same thing that i've been trying to do for months now ;)
Coming into this with an open mind, I think I would have carried the transmitter and had the receiver in the car - like a remote door lock.

The receiver could have had a relay connected that blew the horn when the transmitter was keyed at a distance. How about that?
 

taftech

New Member
pebe said:
Is the transmitter fitted in the car and switched on at all times when you have parked the car, and you carry the receiver?
Yes, I believe this was supposed to work that way. Also the number of leds lit indicate how close you are to the car with the transmitter.


pebe said:
I think I would have carried the transmitter and had the receiver in the car - like a remote door lock.
If the car carries the transmitter, then you can measure how far away the car is with the reciever.
 

pebe

Member
I think you could have trouble getting any meaningful information from the number of LEDs lit up. In a car park the transmitted signal is reflected many times by the metal of all the cars and you can end up with 'dead spots' where you can get no signal, so the LED indication would change as you move about. And how do you know in which direction to go towards your car?

If many people use these devices you could end up by finding the wrong car. :?

If you want to purchase modules to make up the transmitter and receiver then do a Google search for RF Solutions. I think they are international and their bits are sold in the UK by RS, Maplin and probably Farnell. These modules operate in the bands 418 to 434MHz.

Good luck.
 

taftech

New Member
Yes, I realize there are many things wrong with it, even if the schematics did work. However, as I said before.. this is not my intended use for the device.

I have been looking around for different RC moduels, and found these:
http://radiotronix.com/ewmprod.asp

Any idea how hard these would be to use?

Thanks
 

eggelec

New Member
taftech said:
Thank you pebe, for analyzing that for me.

What I would really like to have:

A transmitter with a variable switch that could make the transmitting range between 2'-100'.

A small reciever to accept the signal.

Both, operating on a frequency that would not interfere with other electronics.

The transmitter and reciver only need to be very simple, sending only a single signal between them.

Any input would be bery nice.
Try using a POT to ajust the range
thanks,
Smart
 

Sebi

Active Member
taftech said:
What I would really like to have:

Both, operating on a frequency that would not interfere with other electronics.
Today cannot found a pure frequency,except on GHz-band. My opinion:hopeless to found a car without directional aerial and receiver with hand variable sensitivity. (think about "fox-hunting" sport)
 

eggelec

New Member
taftech said:
I have a few questions about this schematic...
http://www.schematicsforfree.com/misc_circuits/CAR_LOCATOR.GIF


First.. I don't see a power source for the receiver.

Also, the secton of the receiver with the leds, doesn't that need a ground somewhere? I only see one wire going to all of that..

Please, someone look over it and tell me if they think it will work. I am pretty new to making this kind of thing... so I don't really know much about it.

Thanks!
TAF
Dear TAF,
There two lines comming out of the led's aren't there try using the line comming out of the flat side (The side with the horazontal line) as base.
Thanks
 
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