# Remote for car central locking [Resolved]

Status
Not open for further replies.

#### tim_l_012

##### New Member
Hi All,

I have just fitted central locking to my car, (which is very handy btw), and now I am looking at a remote setup for it.

I refuse to pay upwards of $60 AUS for a simple remote add-on, which I beleive could be constructed for much less than this. The only problems are, 1) I am only a beginner with electronics. I have built a few things, using diagrams found on the net and from other forum posts, but I'm not 100% confident making my own things up yet 2) I don't know how radio communication works. 3) I don't have a good looking remote So if you have a diagram or any help relating to a simple remote, I guess it would have to be able to control 3 buttons, "LOCK", "UNLOCK" , and "BOOT".. Apparently I can combine the Lock and Unlock wires to make it alternate, so a 2 channel would suit it ok I guess. If anyone could provide any help on this, it would be much appreciated. Thanks in advance, #### Nigel Goodwin ##### Super Moderator Most Helpful Member To be honest$60 Aus sounds like a bargain! - building it yourself is likely to cost more. You need a transmitter and receiver (you can buy these ready built and licence free - you couldn't build one yourself, it wouldn't meet the licence free regulations). You then need an encoder on the transmitter end (you could use a micro-controller, or a ready built dedicated chip), and a corresponding decoder on the receiver end (again, either micro-controller or dedicated chip).

The 'better' car remote systems also change codes automatically, so people can't simply record your transmitter signal and copy it - so everytime you press the key it sends a new code from a psuedo random sequence, the receiver has to have the same sequence of course.

#### Chilli

Tim, What did you pay for the central locking kit? Really $60 AUS does sound like a bargain. Why re-invent the wheel if you can get a tx/rx at your local hobby shop? #### tim_l_012 ##### New Member Well actually the C/L kit was about$34 AUS!

There is a add-on remote bit but I thought I might be able to build one cheaper.. but obviously not.. the other problem would be the case.. my girlfriend will be using it so it has to be nice.. the ones you buy are not too bad so I'll see what I can do.

I have another question, but its about lights and a beep thing so I'll post another thread.

How much do you think it would have been to build the RF thing anyways?

Tim.

#### Nigel Goodwin

##### Super Moderator
I don't know how much they would be in Australia, but for UK prices have a look at http://www.maplin.co.uk, look under 'A to Z Listing' for 'RF Modules'. Keyfob transmitters there are £9.99 (UK Pounds).

#### tim_l_012

##### New Member
Hmm well I guess the hardest thing would be getting the RF bit working.. I would get around to worrying about a keyfob once its all up and running...

Can you check out my other thread, "Fake a car alarm"

If I can get that going alright then I'll just buy the remote bit.