Garage Remote

[MrT]

Not strictly a Galaxy question but the remote control sender in my Galaxy that opens my garage door has failed. I have traced the fault to the large component in the sender marked "M.E.C. 26.9.95 12/98". I have attached the picture to this message. If you cannot see the component in the picture it is a small silver metal can about 14mm x 8mm x 3mm with two leads, one of which has snapped off.

 

Can anyone accurately identify this component from the description and picture so I can buy a replacement? If more information is required on the component such as a value, where would I get this from, ie would there be further information on the other side of the can if I removed it from the PCB?

[katman]

Not strictly a Galaxy question but the remote control sender in my Galaxy that opens my garage door has failed. I have traced the fault to the large component in the sender marked "M.E.C. 26.9.95 12/98". I have attached the picture to this message.

 

ie would there be further information on the other side of the can if I removed it from the PCB?

Hi MrT

 

The component in question is a Quartz Crystal.

 

Look here for a replacement

 

http://www.rapidelectronics.co.uk/rkmain.a...72013&XPAGENO=1

 

If you look on the other side of it you should see the frequency marked on it something like 4.000MHz

 

That will tell you whick one you need to buy.

 

Hope that helps

 

Keith

[MrT]

Thanks for the quick response.

 

There is nothing on the other side of the Crystal but on reading the front again it looks like a 26.995Mhz crystal. I suppose the transmitter is a 433Mhz (the part number is (A433) which would mean a 16x multiplier. However, I cannot find a 49U Crystal at 26.995Mhz. Is 27Mhz close enough or do they have to be spot on?

[Masked Marauder]

26.995Mhz crystal are common on the AM 27Mhz Remote Control model scale. Whether one would work or not is not something I know much about.

[katman]

Hi MrT

 

Crystals are normally pretty tight on specification. Looking at the Rapid site, the tollerance is 50ppm so 27*50 = 1350 Hz

 

That means a 27MHz crystal could actually be anywhere from 26998650 to 27001350 which even if it were at its lowest tollerance would still be high.

 

A 26.995 Mhz at its highest tolerance would be 26996350 so probably too great a difference.

 

Googling for 26.995 Mhz produces lots of hits for radio controlled models.

 

http://www.jperkinsdistribution.co.uk/deta...eneral%20spares

 

Sorry I cant find one from my normal suppliers eg Rapid / Farnell / RS etc.

 

If you can bear to search the Maplin website you might find one but I have a pasionate hatred of Maplin since they stopped being a top quality electronics component supplier and insted became a toyshop full of crap!

 

Regards

 

Keith

[bigdaddy]

No disrespect to katman,,,,, :) I like MAPLINS,,,, :)

 

No they do not sell a 26.995 quartz crystal,,,, :)

 

I am only guessing,,,but could you not change the recieving crystal to match the transmitting crystal,,,,ie: change both crystals to 20mhz,,,,, :)

[katman]

No disrespect to katman,,,,, :)    I like MAPLINS,,,, :)

 

I *used* to LOVE Maplin.

 

I spent thousands with them over the years having started buying from them in 1979.

 

One of my two customer numbers is less than 12000 because I was there when they introduced them.

 

I religiously used to sit and read through the catalogue in my lunchhour when a new catalogue was released and also having a trade account I got a free copy of the catalogue.

 

Several years ago I didnt get my free catalogue so rang up to ask why. I was told it was because I hadnt spent enough to warrant being sent one.

 

I informed them that if they looked back through all my previous orders they would see why I hadnt spent enough.

 

THEY STOPPED SELLING THE COMPONENTS I WAS BUYING

 

They werent obscure compenent either, but management at Maplin had changed and whoever was in charge decided that Maplin should be more like Tandy :)

 

Its impossible to spend money with a company if they dont sell what you want!

 

Regards

 

Keith

[sasquartch]

The 50ppm figure quoted for crystals normally relates to the stability, rather than an absolute tolerance. All this means is that the frequency will not drift by more than 50ppm. So a very close crystal will probably be fine especially for an application like this

[bigdaddy]

katman

Yep cant fault your reply,,,if they dont sell it, then you wont shop there,,,,makes sense,,,,,, :)

[Masked Marauder]

I spoke to a friend of mine who used to be a Manager for Tandy before they became a toy shop. He now works as an electronics designer and is currently working on a HUD for cars.

 

He said that a TX radio control crystal should be within tolerance, but without seeing the circuit he can not be 100% sure.

[MrT]

I will try with a 27Mhz Crystal as after all it is just the (433Mhz) carrier frequency of the radio signal , not a synchronous digital transmission, so the difference in frequency should only mean a minor decrease in signal, the cut off filters are not that sharp.

[Guest MATT]

i think a 26.995 Mhz crystal comes under the 27Mhz band, and simply defines a channel. in other words, your neighbour can have a remotely operated garage, and when he opens his, yours wont open, because the frequency or "channel" is slightly different. so i think a 27Mhz crystal should work.

 

MATT

[popeye2755]

Out of interest, how do you know it's the crystal that's failed?

 

cheers

[popeye2755]

Sorry, forget my last post!!!

[Guest MATT]

been a long day?

 

MATT :)

[popeye2755]

Long day? Try long week!

[Guest MATT]

:)

 

MATT :D

[MrT]

The 27Mhz crystal did not work and I considered changing the crystal in the receiver as well to match, but oddly it was a different frequency again, 26.564Mhz. I am not sure why the Tx and Rx should have different frequencies.

 

Then again I may have damaged the dual-layer board when removing the Xtal.