Hello friends,

I built the circuit on the main page here:
http://www.serasidis.gr/circuits/RF_...te_control.htm

I did the same thing only I used an avr 90S2313, and a 9 Volt battery with a 5 volt regulator. The transmitter module and the avr are working from 5 volts.
Everything works perfectly except In the transmitter, the battery goes dead within one day. Anyone have experience with this circuit?

Could the regulator be draining the battery somehow?

The software puts the microcontroller to sleep so that it does not use much power. I am sure that it is not a software problem.

Anyone with any experience with these modules?

 

You need to disconnect the battery when it's not used - the regulator will flatten the battery as it's always powered. This is why remote controls don't have 9V batteries and regulators!.

__________________
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http://www.winpicprog.co.uk

 

Hi John,

Why use the regulator with the transmitter? It's not on the schematic, and with the voltage input range those chips accept, I wouldn't think it's needed when running from a battery anyway.

Why run the circuit on 5V when 3V will do the job? Or 4.5V, which you could get from 3 AA cells with probably better capacity than the 9V.

http://en.wikipedia.org/wiki/Battery...nd_discharging

The regulator itself takes power to do its job, and unless it's a low-dropout regulator you probably don't want to use it.

Try removing the regulator and running the thing off of 3 AA cells.


Torben

 

A 9V battery has six tiny AAAA cells in series. They don't have any capacity.
AAA cells have twice as much capacity.
AA cells have 4.6 times the capacity of a 9V alkaline battery.

__________________
Uncle $crooge

 

hello guys,
thanks for the input. Firstly I am using the parts I have here without having to order anything. I am trying to make due with what I have.

I was using the regulator because I am running a 90S2313-10 micro with the RF module. The 90S2313 requires a minimum of 4 Volts. So I thought I would run a 9V battery, but in less than 24 hrs, it went dead! I didn't have a battery holder for 3 AA batteries.

I have since re-worked the remote so that it does disconnect the battery when not in use. When the button is pushed, the power is connected briefly in order to send the data packet, then it disconnects the battery and waits for the button to be pushed again.

I think this will do the trick.

Thanks again for the input!

 

There ya go. Of course, now I want to build one--thanks for the link to the project.

Also, if you happen to wander through a Radio Shack or whatever and get a chance to pick up a holder for the AAs (you could probably get away with 4 AAs too, as long as fresh ones don't exceed 6.6V IIRC--the holder might be more common), you can always pull out the regulator and use those instead of the 9V. Together with your power-on-demand switch setup, that should give you capacity for ages.

At any rate, good going and good luck!


Torben

 

I'd like to try 3 AA batteries without modifying the code.(4.5V NO regulator.)
That is, keep the micro running in sleep mode, and wake it with a keypress on low level interrupt.

Just curious on how long the battery will last.

I installed the transmitter approx 170' away from the receiver, and it works like a charm. I am using a 3" copper wire for an antenna for both RX and TX (the center conductor from an RG6 cable)

The transmitter is outside, in my mailbox. When the mailbox is opened, it signals the receiver to turn on an led and beep a buzzer. The led stays lit until reset. We can't see the mailbox from the house, so it's nice to know whether we have mail or not.

I am also curious to know how the circuit will perform in the freezing cold winter.

 

Well in sleep mode the PIC isn't actually running, it's asleep.

Massively better, with a regulator from 9V you were wasting almost 50% of the power before you start, and using an expensive tiny capacity battery.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Hm. Not too sure how to do this calculation Right(TM), but using ideal numbers: you have 3 cells holding ~2500 mAh each, but they're in series so IIRC you don't get to add up the capacities (just the voltage). The circuit supposedly draws around 1uA in sleep mode (well, the AVR does and the rest of the thing shouldn't be adding too much to that), and this fellow says he measured around 14mA when any button is pressed on a very similar circuit, which also seems to jibe with what the TLP434A data sheet says. So if the thing were to transmit full-time on fresh batteries, you might get 2500 / 14 = ~178 hours out of it (ignoring environmental and self-discharge issues, and ignoring the fact that it will probably stop working long before 178 hours have passed since the cells' voltages will likely drop too much to keep going). I'm assuming alkaline batteries here. Also, assuming that the the thing will only transmit at most once per day, on 5 days out of the week, for long enough to turn on your LED/buzzer thing--maybe a second?--that's...um...5 seconds a week at 14mA draw, and 604,795 seconds a week at ~1uA. I'm sure you can see where I'm going with this.

n.b. Somebody who sees problems with my math/assumptions please beat me (gently) with a clue stick if I really screwed that up.

That's a 1/8 wavelength antenna; the original designer recommended a 1/2 wavelength; I don't know how much of a difference it would make to your application. A 1/4 wavelength antenna might be a nice compromise at 6-7".

Neat! It occurs to me that I have no idea where you are (you haven't filled in the location in your profile) but do you need any kind of license to operate on that frequency where you are? If the thing is only sending one pulse a day then it's unlikely that anyone will really notice, though.

Hm. The TLP434A is rated -20C to 80C, and the AVR90S2313-10 can be rated at 0C to 70C for the AVR90S2313-10PC and AVR90S2313-10SC, or -40C to 85C for the AVR90S2313-10PI (http://www.chipdocs.com/datasheets/d...S2313-10.html).

It also depends on the batteries; chemical reactions slow down in cold temperatures. I am not too sure what the best cells for your temp. range would be. I also can't tell you about how the crystal will respond, although I'd guess it will slow a bit. Enough to affect the circuit? I don't know.


Torben

 

Battery still working good after 3 months of winter!