433.92 MHz data repeater - thoughts ?

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Dippy

Moderator
I'm going to make an interociterorial antenna this afternoon.


For UK users don't forget about the regulations concerning gain antenna on Tx.....
 
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eclectic

Moderator
srnet said:
You can make a parabolic reflector for poking onto the stubby antennas, at least that way you are directing the power where you want it.

Made out of card and alluminium foil\tape, laminated for durability.

I use them for my WiFi setup at howm, they definetly help, cant see why they would not work at 432Mhz.

Templates can be found on the Internet, simple to make.
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@srnet

Have a look at Stan's work here:

http://www.usbwifi.orconhosting.net.nz/

His whole site is enormous
and worth a browse or two.
e
 
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Dippy

Moderator
If referring to me (and bless you for thinking of me) then no, not 'policing' at all, you do what you like in your neighbourhood. No problem.
I'm just asking people to be a little considerate.
I don't people to end up in trouble with neighbours or the authorities.

Is that so wrong?
If so, tell me. I've got very thick skin to match my head.
 
J

John West

Senior Member
Dippy makes a good point. But with a worldwide audience on this forum, it's of necessity up to the individuals posting and reading these RF threads to know what their own licensing levels are, to know what their local RF regulations are, and to abide by them. And also, if they live in congested areas, to simply be considerate of their neighbors.

But for those in rural areas, and with licenses to communicate on multiple bands at high power with unlimited antennas, there's simply no end to the fun to be had with PICAXE's and RF gear.
 
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papaof2

Senior Member
Dippy said:
If referring to me (and bless you for thinking of me) then no, not 'policing' at all, you do what you like in your neighbourhood. No problem.
I'm just asking people to be a little considerate.
I don't people to end up in trouble with neighbours or the authorities.
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You could wind up causing problems for yourself. I tried one inexpensive transmitter that completely blocked the garage door opener receiver from perhaps 30 feet away horizontally and through two walls. When this transmitter was operating, the handheld transmitter for the opener wasn't recognized even when brought within 5 feet of the opener.

The intended use for the transmitter/receiver pair is in a remote area, so there'll be nothing nearby that it can interfere with - the trees and animals won't notice.

John
 
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John West

Senior Member
Goeytex said:
I need an omnidirectional pattern but I'll keep that in mind for future use. Next I am gonna make a colinear antenna and test.
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Double check the velocity factor of the actual coax you are going to be using. It can vary quite a bit depending on the dielectric used in the cable. A cable name like "RG58U" just isn't enough info these days.
 
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Goeytex

Senior Member
@DIPPY

How many times do we need to warn folks of the need to be considerate and follow the rules as much as is possible and practical ?
Does it need to be incessant on every RF thread ? Anytime someone mentions a high gain antenna ?

Why not post a sticky for all to see rather than derailing ever RF thread with the whining and sarcasm ?

Put your thinking cap on. If a higher gain antenna is used with with a programmable module like the Dorji, then the RF power can be reduced to get adequate range while using less battery. No rules broken. Sheesh ! ..... This is getting kinda lame ....
 
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John West

Senior Member
Goeytex, As the forum lacks a title bar that warns folks about everything from PICAXE automotive uses to RF regulations, it behooves the forum moderators to include that sort of info in threads. Info on filter caps and programming resistors gets regurgitated on a regular basis as well. There are new readers to this forum every day who lack such important info who haven't read any of the previous threads where such info is brought up. Old timers can skip on by it without harm.
 
Buzby

Buzby

Senior Member
Somewhere in yet another dark crevice, I've got a second hand cardiac pacemaker. Quite old, mid 80's I think, so it probably could do with some new parts.
What batteries do you think I should use ?. Those polywolly lion things look good, they should keep it running for years.
The electric bits I was thinking of upgrading with one of those AXPIC chips. Should I use one with 8 legs or 20 ?.

I'd like to get it going again, I might need it some day.

P.S. I want to make it radio controlled. What wireless modules would you suggest ?. I should think a 7Km range should be enough, our local hospital is only about 5Km away.
 
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John West

Senior Member
Buzby, any old battery should work. Those heart things are pretty low power. And you'd likely be OK with an old wall-wart supply to keep it going around the house. The Chinese make some pretty inexpensive ones. But be sure to build an automobile adapter to plug in quickly for the trip to the hospital. Just in case. I've seen some interesting circuits for them on the web that oughta do the trick.

As for the AXEPIC thing, you can probably use one of those 20 pin ones, and if it's too big just cut it down a bit.

Just be sure to use some good glue to connect all the wires with and you'll be fine. ;)
 
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Paix

Senior Member
Buzby said:
Somewhere in yet another dark crevice, I've got a second hand cardiac pacemaker..
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Do tell Buzby, it sounds extremely personal and very painful . . .

= = =

The warnings aren't half as annoying as the extended bleating about them however. :) The bleats and counter bleats do give opportunities for a little light humour, but tend to screw up the train of threads.
 
Buzby

Buzby

Senior Member
Hi Paix,

It was one of things I saw on e**y, and thought 'I want that' . How often do you get the chance to buy a pacemaker ?. ( It cost less than £10, so it wasn't too expensive for a laugh. )

It's a real talking point, if a little odd. !

P.S. It probably did *not* come out of a dead person. Back in those days they were changed every couple of years, they didn't have pollywolly lion batteries then.
 
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manuka

Senior Member
Back on topic (!), I keenly appreciate diverse 433 MHz ISM regs. & again point out that it's quite legal to add receiving antenna. Simple roll your own types have been endlessly discussed on the Forum, especially "Cotanga" Yagi and "Slim JIM". Both are capable of ~6dB gain (= range doubling), with the squashed radiation pattern of the Slim JIM particularly handy for omnidirectional terrestrial use -forget them for satellites!

Aside from elevation & selecting a clear RF "take off", if local regs. ban TX antenna then consider enhancing transmissions with a decent ground plane- even a car rooftop can do. A suitably placed reflector (open wire mesh perhaps) behind the setup can also be effective. It's positioning should relate to the 433 MHz wavelength of ~700mm - experiment with ¼ & ½ wavelength spacings.

N.B. Parabolic reflectors need to be at least a couple of wavelengths across to be effective.At 433 MHz a dish will be golf umbrella sized & inconveniently bulky- see pix below. Hence forget parabolic approaches at low UHF! They're however dead easy to rustle up at 2.4GHz (for WiFi,BT,ZigBee etc) as a wavelength then is only ~125mm, and a "wokfi" dish need only be used for gains of ~12-15dBi.

Stan. (ZL2APS, & antenna wrangler since 1961)
 

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manuka

Senior Member
Very on topic! I've been ZL2APS since the late 1960s,but -thanks to the time shifting & flexibiity of the internet- am seldom on the (voice) ham bands these days.
 
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srnet

Senior Member
One of the benefits of data modules operating on 432Mhz, is that it is close to the amateur 70CM band, so its no surprise there are plenty of DIY antennas and ready built ones too.

For my direction finding exploits I have a 7 Element ZL special, good gain and short. But its not exactly the sort of thing you would carry around in its assembled form.
 
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phillid

Member
manuka said:
Very on topic! I've been ZL2APS since the late 1960s,but -thanks to the time shifting & flexibiity of the internet- am seldom on the (voice) ham bands these days.
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Huh cool, I'm in my mid teens and have been studying to become a radio amateur :)
 
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manuka

Senior Member
Great! In spite of the ease of modern comms., a ham ticket is still a worthwhile career addition as it shows you're REALLY keen on the wireless- & probably also have a valuable "hands on" attitude. I've known NZ tech. jobs to be landed on this basis,with applicants who eat & breath electrons winning positions ahead of mere (but better qualified) "arm chair" technologists.

Where are you in Wellington? Do you have any ham gear - at the least a general coverage digital receiver ? Many ham old timers are often delighted to give such gear away to budding bright sparks!
Shoot me a 1:1 email perhaps - address at bottom of www.picaxe.orcon.net.nz/dorji434.htm Stan.
 
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