WHERE CAN I BUY THESE DIODES FROM? I'M LOOKING FOR THE ONES NEEDED FOR ATTACHING THE TRIGGERS FOR THE DOORS TO THE ALARM. I TRIED LOOKING AT THE LOCAL RADIO SHACK BUT DIDN'T KNOW WHICH TYPE. I SAW IN THE WEB SITE SOMETHING ABOUT A 4000 SERIES. I KNOW WE NEED A 1 AMP DIODE BUT WHAT WATTAGE, I CAN'T SEEM TO FIND A 12V. ANY HELP IS APPRECIATED. THANKS.
ok you should be able to find diodes at radio shack the one that will work will say 1N4004 on the package they also have a pack of assorted diodes that i have bought before at radio shack and that diode as well as others will be in there.I also believe there is a 1N4005 that will work as well.
Oh yeah if you get a pack of the 1N4004 thewre verry good to have as you can use them for a variety of things in a car.They are rated at 1 amp and that is what youll mostly use on low current circiuts
Hey dexinefx,
Just as a reference when selecting diodes. The last digit gives you an idea of its current carrying capabilities. For example an 1N4001 is a one amp, a 1N4004 is a four amp, etc...
Also one amp is sufficient for door trigger isolation. 
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Prepare your future. It wasn't the lack of stones that killed the stone age.
ACTUALLY THAT INFO IS WRONG THE 1N4004 IS A ONE AMP LIKE I SAID EARLIER IN THIS POST AND A 3 AMP DIODE WELL THAT ONE WOULD BE IN5402 SO YOU SEE THAT NUMBER IN THE END REALLY DONT HELP MUCH OR MEAN MUCH.
IT REALLY DONT MATER JUST LETTING YOU KNOW .
mobiletoys2002 is correct. The 1N4001 is a common model number that distributors and manufaacturer's use, but not all of them use it. I know that Select uses this reference number and as Big Dog pointed ouot the last digit goes up according to amperage isolation . Make sure you check the package for the proper amperage and voltage for these and like Big Dog said, 1 amp is more than sufficient for door triggers.
Here's a passage from a article I found on the web about the diode classification :
Device Numbering Systems
Semiconductor devices are classified by the manufacturer using a unique part numbering system. There are many systems in use, but here are some popular schemes in detail; the European based Pro-electron system, the American based JEDEC system and the Japenese based JIS system. Major manufacturers introduce their own schemes as well.
JEDEC Numbering System
The JEDEC system, ( J oint Electron Device Engineering Council. This system has the following format:
digit, letter, serial number, [suffix]
Digit:
The first digit designates the amount of P-N junctions in the device. So a device starting with "2" would contain 2 P-N junctions and would most likely be either a transistor or a FET. Common part numbers are listed below:
1. Diodes
2. Bipolar transistors or Field Effect Transistors
3. Double Gate MOSFETS, SCR's
4. Opto Couplers
Letter:
The letter is always "N", and the remaining figures contain the device serial number.
Serial Number:
The serial number runs from 100 to 9999 and indicates nothing about the transistor.
Suffix:
If a suffix is present then this indicates the gain group as below:
A = low gain
B = medium gain
C = high gain
No suffix = ungrouped (any gain).
So for example, 1N4001 would be a diode and 3N201 would be a double gate MOSFET.
As to your question mobiletoys2002, the voltage you will need is 50 volts. Most are 50 volts and it would not hurt to get larger voltage if you don't find any around your local electronics store.
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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA