433MHz Wireless Units Dead?

Hey Guys,

I have a wireless Tx'r and Rx'r, and they used to work fine. The aerial was always hard to get right, took me a long time.

Is there a way of mismatching the aerials resulting in death of the unit? IE, can I kill a unit with the aerial being wrong?

I think these units are dead, which sucks...


Thanks for the help, this is a great forum!

Bye,

MM
 

manuka

Senior Member
MM: 433 MHz units are such low power (~5mW) that a "no go" due to poor antenna SWR is unlikely. How about -ah- you tell us the TX/RX models & just what you were doing?! Stan
 

eclectic

Moderator
MM
Normally, they're tough little beasts, and AFAIK,
antenna mismatch should not kill them.

1. Can you supply more information on your setup
(models / circuit / layout/ power / program)?

2. Do you have access to a 'scope?

e

Editadd crossed posts.
 

westaust55

Moderator
Maybe also:
- a link to the relevant website datasheets for Tx and Rx modules
- a photo of each "end" clearly showing how you have them connected
 

moxhamj

New Member
Hmm. Receiver voltage is 5V. Transmitter is 3V. Usually transmitters are a range of voltages (I've some that go 3-12V) but this one seems to have 3V as the absolute maximum rating.

So those voltages might need to be exact. Eg a power supply >7V (5 alkalines or 6 nicads), and a 5V reg for the Rx and a 3V reg for the Tx.

It helps when debugging to have spares for both Tx and Rx - at least then you can work out which unit is not working. You might get a clue as Andrew Cowan says by feeding the Rx into an audio amp.
 
I have two RX units, one old version and one new version (new version looks like the picture)

The picasa links for some reason don't link to the picture...

Anyway, I get lots of noise on the old RXr and silence on the new. If I put the txr's aerail through a loop in the old rx'r, then I get crystal clear reception. If I move the TX'r away from the unit (and inch or so) then reception dies. I have tried a billion different aerials with no success.

Working units look like this: http://www.picaxe.orconhosting.net.nz/433txrx.jpg
 

westaust55

Moderator
Jaycar Keymark 433MHz Tx and Rx modules

I am using those Jaycar supplied Keymark Tx and Rx modules.

With the transmitter, at 3V (per the datasheet from Jaycar), I had no signal (luck) even when the Tx and Rx modules were only around 1 metre apart. Stepped up to 5V for the Tx (Rx was always on 5V)and all worked perfectly.

with respect to your program, have a look at the code and comments (in particular the pause between SEROUT commands) in this thread http://www.picaxeforum.co.uk/showthread.php?t=11749&p=96023
 
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The thing is, the TXr was meant to be powered from a solar garden light. The voltage gets up to about four volts...

I shall try stepping up the voltage to see if that fixes the problem, thanks for the tips!
 

Dippy

Moderator
Have you checked the current when the things are operating?

You say when the range is zero the old Rx works OK, what about the new Rx?
Or does it stubbornly stay at zero output?

Have you checked the PCBs for damage? (Track breaks / corrosion etc.)

I have never used those particular modules, but on the modules I have used the Rx o/p is usually noisy.

I am easily confused, but is Westy saying that they are OK at 5V even though the Data Sheet says 3V max?

Are they expensive? Maybe easier to buy some more rather than wrestle for days?
 

westaust55

Moderator
. . . but is Westy saying that they are OK at 5V even though the Data Sheet says 3V max?

Are they expensive? Maybe easier to buy some more rather than wrestle for days?
Yes, I have been operating the keymark Tx modules at 4.5V and 5Vdc without mishap. Believe manuka does likewise.

Cost of each TX and/or Rx module from Jaycar is AUD$13ea or NZ$15.90ea

Another point I found was: having the Tx module extremely close to a circuit that generated a ~6kHz seemed to stop transmission.

The current draw can peak around 10mA during transmission. I used a transistor to switch off the Tx module when no transmission was in progress to save battery power.
 
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manuka

Senior Member
These Jaycar Keymark 433 MHz units have been around for ~5 years, & at one stage their supply voltage instructions indeed were incorrect. After cross checking the Keymark data, I emailed & told them (many times...)

The TX works well around 5V & is not picky with supply level, perhaps running to 12V,but the RX MUST be close to 5V. All my work with them has been with 3 x fresh AA alkalines or 4 x NiCD/NiMH (~ 4.8V)- the RX will cease working at < 4.5 V I recall.

I haven't bought any since ~ 2006, so am unaware of changes. Mmm- it's possible yours may not be 433 MHz - I recall they can be issued at 315 MHz too, & thus an oddball may have slipped in. Check the fine print!

IF YOUR CIRCUITRY & CODE IS 100% CORRECT I suggest you touch Jaycar for a fresh pair to run a simple go/no-go check.
 
You know Andrew H right? From Opunake, he's mentor at a place called brightsparks and he gives out "parts for points". You get points by making posts in the forum etc...

So I bought some off him, and ended up with two TX and two RX.

He is currently travelling around the country, so I'll have to wait til he gets back.

I think it will be much easier to get some fresh ones...

I will also try using 5v on the RX unit, hopefully that helps =)
 
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