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PIR motion detector wireless UHF 433MHz alarm

Foreword:
I wanted some sort of audio alarm in my bed room, to give a sound in case someone snoop arround in my front yard
i kind of figured just in case i ever hear a sound i show up and kick them back to the future.
anyways here is how i hammered this project together in a few hrs. so prepare for fast and ugly hot glue maximum.

what comes first, the transmitter or the receiver ?
Here an ultra fast mock up of the receiver, I just used a random scrap pcb with an AVR MEGA168 so I could test and check the transmitter design
how much lead in until AGC is working good and stable, how fast and how slow data rates for best range
when all the simple radio parameters was found, I made the transmitter as perfect as possible, and the receiver code adjusted after that
4mS leadin, 1mS = 0, 2mS = 1, that is hos i send my bytes, each byte start with a lead in.. each data transmission starts with 4 bytes of zero,
this way AGC is stable.

I used the stamp sized TX and RX modules from ebay, TX is called SYN115 the one with the little 6 pin IC
the RX is called SYN480R the one with the larger 8 pin IC.

Bottom side, keywords : LC Technology 433MHz ASK Transmitter Module Wireless SYN115
on ebay you get both the RX and the TX for 1.65$
This type of AM 433MHz actually works, and really well, amazingly good range and repeatability

the PIR sensor is also a very cheap module from ebay, the case is from a real pir wireless unit, brand new in case,
just too bad it did not work any way possible near what i needed, and no way to reconfigure it or modify it, so scrap the electronics, and in with your own

where this one is installed I got a 12V supply anyways, the weak green led is good for debug it is live
when I walk pass this sensor, it say beep-beep in a special two tone way, short and nice, this way an intruder know he is detected
i put in a dead-time of 45 mins, so it need no movement for 45 mins, before it arm it self again,
this way i dont hear the beeps, in case i need to work in the garden

looks almost original from the outside, power supply connector, power led, and sounder at the bottom, reveal my little upgrade.

Transmitter ready to be mounted

The receiver : I was running out of patience, so I just cut the scrap test pcb to fit into a case from the first useless scrap system i got stocked

I use an old phone charger 5V wall plug powersupply, so I dont even need a local regulator in the receiver, lets reuse all old stocked parts we can.

with "battery" compartment lit on, it now looks almost original again

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2018 Thomas Scherrer OZ2CPU
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