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Topic: power for rf module (Read 786 times) previous topic - next topic

thedovid

i'm using this:
http://cal-eng.com/?wpsc-product=atmega8_8mhz

So, really, that's the whole circuit (minus the led i use to indicate that a message is received)

When I upload sketches, I connect this:
http://cal-eng.com/?wpsc-product=ftdibridge-usb-serial-transceiver

But after that, I take it out and am left with a very simple circuit.

Like I said, it works with the coin cell batteries.  I had it sitting on one side of the room, by itself, blinking every time it received a message from the transmitter on the other side of the room.  I just don't want to rely on those small (and expensive) batteries for this project, and I'd like to understand what's happening so I can apply the knowledge to future endeavors for ever and ever.


majenko

My guess is that the coin cells have a lower internal resistance than the AA batteries, and thus can react to transients much faster, compensating for your lack of decoupling capacitors.
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perhof

In addition to decoupling caps you should add a pull-up resistor on the reset pin.

thedovid

Majenko: can you explain decoupling caps?  What capacitors should i use?  Where do I put them?

Perhof: I use a pull-up resistor on the reset pin when I'm connected tot he usb module for uploading code.  Why would I need it during regular, stand-alone use, and how would it help me problem?

perhof

Leaving the reset pin unconnected leaves it floating.
The result could be random or continuous resets.

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