Micro power transmitter for remote sensor help

glena · Joined: 25 Jul 2007 Posts: 284 Location: PA near Philly

You may want to look at this technology. Its battery can last up to 4 years and transmits when it gets low. There is also tamper detection.

http://www.alarmcontacts.com/product.php?productid=1035

-Glen

laborratte · Joined: 27 Jul 2005 Posts: 305 Location: Berlin

1. I would NOT just heartbeat a carrier signal, your receiver could easily disturbed by any mobile phone. Send a short message (like every remote control).

2. A radio module comsumes typically 10mA@5V. Assuming you send a message for 20ms per second, you can calculate:

20ms * 10mA = 0,2mAs per Second = 0,2mAh per hour

This is 4,8mAh per day or 1752mAh per year. 3 AA cells shoud do that.

If you have other radio modules or time schedules, just recalulate.

3. I personal wouldn't mount any sensors on a saltwater-splashing-and-pressure-hose-cleaned-cup at all. There are plenty of industrial sensors (optical/capacitive) which can "remotly" detect liquids. (for industrial amount of bucks, of course).

beananimal · Posted: Wed Apr 20, 2011 4:16 pm Post subject:

beananimal · Posted: Wed Apr 20, 2011 4:20 pm Post subject:

kimmi · Joined: 24 Feb 2006 Posts: 1922 Location: Denmark

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albertsm · Joined: 09 Apr 2004 Posts: 6198 Location: Holland

I have removed a number of posts from this topic.
Please continue this thread with relevant info and respect.
I do not really like to remove posts.

I also moved this topic to Various since it has not much to do with BASCOM-AVR.

laborratte · Joined: 27 Jul 2005 Posts: 305 Location: Berlin

beananimal · Posted: Thu Apr 21, 2011 1:52 pm Post subject:

Thank you for the response. I think I have a starting point and will post back once I find a few modules that appear suitable.

beananimal · Posted: Fri Apr 22, 2011 5:08 pm Post subject:

So it looks like I have 2 basic choices:

1) use one of the very cheap 433mHz type transmitters that sparkfun and others sell. These thing appear to be not much more than a simple transistor and inductor type transmitter. From what I read, they work but can be rather hard to get talking due to noise. The nice part is the low powr consumption of as little as 4mA during transmit. Power could be cut easily during the sleep mode, but noise is likely at each wakup. I thought maybe a fixed front end (555 timers or other oscillator) could be used to set the hearbeat. Maybe hard to deal with on the reciever end.

2) use a Zigbee (Xbee ZB) type of transmitter. Has a sleep mode that consumes alost nothing, but transmit current is above 40mA. This makes power magement much harder. However, communication is much less prone to drop-out due ot noise, etc. This could be setup with a picoPower AVR that wakes up every 2 seconds and sends an "OK" or similar serail message and then goes back to sleep.

I have no experience with either type of transmitter but am leaning towads the Xbee ZB module connected to a picopower AVR. What I don't know is how quickly I can enable this guy, send the ACK and put it back to sleep. Do any of you have any experience in this area?

kimmi · Joined: 24 Feb 2006 Posts: 1922 Location: Denmark

Hi ,
Just a Idea ,
You say it only have to work a few meters ,
do you think a IR or IRDA led can do the job for you ?

beananimal · Posted: Sat Apr 23, 2011 6:14 pm Post subject:

I guess I should consider IR. The area does have several metal halide and fluorescent fixtures that output UV and are in very close proximity 1 or 2 feet from the devices (sensor and controller) so a little bit of testing would need to be done to ensure that there is no significant interferene.