Remote doorbells & BX plip ...

[AndersDK]

Anyone messed around with those cheapy RF remote doorbell sets ?

Wife came home with such a set (sender + receiver) from the supermarket. Cost : some £5. Took less than 10min to install.
At that price it's almost too expensive to heat up your old rusty soldering iron for any home project

The sender unit is indeed very small and would easily fit a common handsender casing - using a 3V coin battery.
For use as a RF Plip unit however, it would certainly need some extra means of coding/decoding. But for a remote garage door opener system it would fit the bill, as it's very easy to modify the receiver for a motor relay driver.

Anyone know the type/make of IC's used - even know of a schematic on the web ?
Tom ?

(I'm certainly buying an extra set to play with )

[tom]

Yes, I'm here. I've just finished etching the PCB for the BX cooling system computer which will finally be ready next week. With regard to the RF doorbell plip, this is entirely feasable. I build my own decoders witha PIC chip pair but Maplin Electronics sell an encoder/decoder pair for about 100DKR and a transmitter and receiver pair for 100DKR which, with a bit of stripboard and a couple of relays will interface with the central locking system. www.rfsolutions.com will find what you are after and I will get around to drawing out a circuit diagram before long. I don't know how to post it on the web Anders, so I shall probably have to post it to you when I've done it. I schemed it up to work by cutting two wires into the CLS box so that I could still use both front door locks for central locking and the plip as well. I suppose that I could design a PCB and that would make building it easier so I'll get started on it next week.

[M]

TOM - Send it (if you can scan & email it) to me or Jon & we will post it up on 'tinterweb.

[Mike E (uk)]

Many after market alarms have an output suitable for controlling central locking. Maplin do a range of them, and they are very good value.

The circuit to interface with the BX central locking is very simple, just a couple of transistors.

If you are going to fit a new remote controller, you may as well fit an alarm and immobiliser too while you are there.

These older cars seem to be targeted somewhat by the thieving low life because more modern cars have better security.

Mike

[tom]

To interface the doorbell, use the output to clock a CD 4040 as a divide by 2 and put the 4040 outputs through a dual monostable(f.eks.7556) to get sequential lock and unlock. Monostable outputs through 22K to a pair of BC549 or similar, emitters to earth and collectors to CLS inputs. All the bits can be obtained in Dk for less than 25DKR I guess. Conrad catalogue?

[AndersDK]

Yeah - well

I was thinking of taking the remote doorbell circuit straight away - as it's got some 100m range. Difficulty is that the circuit only has 4 jumpers to select a different code than any nearby neighbours are using.
I was NOT hinking of incorporating the existing IR plip codec circuits.

This means that if I install the remote doorbell circuits in my BX, park the BX in town near someone using the same type doorbell (and the same code selected), there will be nice activity in my BX as well, when someone have visitors at their frontdoor

Connecting the good ole IR plip codec up front the RF doorbell transmitter is of course one solution to this - but not that elegant.

Anyways - I'll report back when I get my new £5 playtoy and desiccated it. It really looks like a cheap universal RF remote set for those standard on/off controls with an antitheft key code needed