HISTORY:
Sustainability is the name of the game! Anything (that has been tested and still functioning properly) should be repurposed creating saving in wasted Ee and reducing the poisoning our environment when items are buried in the earth at the local tip needlessly.
Never heard of Ee? It is a concept that creates a measurement of ALL things (not just electronics) that humans have made and the energy used in obtaining the raw material, processing the materials right through to a finished product and even should include the shipping of the item to the distributors/retailers.
If you would like to know more about Ee values, please take a look HERE
Being very adverse to "throwing things out" (that may be useful), here is an electronic module from around 40 years ago!
What could you do with it? (I hear you ask, standing on one leg, head cocked to the side and one eye closed)
In the unlikely situation that you had an EDM receiver which can have the matching codes set up AND running on the same frequency, use it for a remote alarm alert system. With the 1 Watt RF output you should be able to easily achieve 1Km distance between this unit and the receiver (subject to the surrounding terrain)
OR
Remove the PCB and connectors and the top metallic ID label (easy) and you have a nice strong Black enclosure for your own custom project (probably, but limited to, RF) inside this nice tough enclosure
EDM (Electronics Design & Manufacturing) was a Prospect, Sydney based electronics manufacturing company that was well known for their alarm system products. Beginning operations around 1985, I am not 100% sure but I suspect they either changed name or were absorbed into Ness, now based in Seven Hills
While sorting through the myriad of equipment I am clearing out, I found this little beauty - actually two of them.
NEW Old Stock!
They were still in their plastic packaging and bought as an accessory for an alarm system that we never installed.
This module is an RF transmitter, pure and simple and it sends PCM codes which are preset by the user. Apply power and away it goes, no data or other inputs, just power it up and it transmits.
EDM - RF Transmitter Module
Model: Radio Alert or the instruction sheet refers to it as Type TX2
Circa late 1980's (based on EDM registering their business name in 1985 and the telephone number on the top metallic label does NOT have the 9, so it was pre 1994 ~ 1995 when the telephone numbering system had a 9 added to landline numbers).
RF Output power: 1 Watt into 50 Ohms
Frequency: 149.300Mhz (not marked on the PCB, enclosure or the paperwork but I have verified this frequency with a spectrum analyser, see my test notes below)
10 position code setting switch
Two piece all metal enclosure, no screws as it uses a "latching" system on the top section - move it slightly and the top can be easily removed.
No feet but two pre-drilled holes for mounting
DIMENSIONS:
111mm L x 68mm W x 30mm H
Folded sheet steel (very strong) 1.2mm thickness
Matt Black finish
Weight (with PCB installed) 250g
COSMETIC CONDITION:
NEW Old Stock
For all these years, this module has been sitting in the original plastic packet
NO scratches
NO dents
Original instruction sheet comes with ONE unit, I will need to photocopy this if you wished to have instruction sheets for both units
NOTE: Instruction sheet is quite detailed, even providing information on how to tune to RF output stage but there are no schematics.
TESTING:
I wanted to look around inside and while doing this, fired it up to ensure it worked and on what frequency. No data or enable/disable communication with the box, simply apply 12V DC (11 ~ 14V is fine) at the rear screw terminals and away she goes.
Using a spectrum analyser I was able to see the TX output is on 149.3000Mhz and that distinctive PWM code stream can be heard.
What's inside?
RF output transistor 2N2219A
Crystal locked
MM53200N (generates a 12 bit width data stream based on the code switches selected)
Single sided board
This module is working fine (as I have two, both have been tested)
I have now placed this module, along with the insructions, back into a nice little sealed clear plastic packet while it awaits a new experimenter to make use of it - finally!
