Hi,
http://openenergymonitor.org/emon/emontx/make/assemble/buildguide22
Following the build guide, I'm just after doing the voltage check and got above 3.3V.
Between GND and VCC: 6.3V
Between GND and PWR: 10.4V
This would have been my first time soldering but I think I done a pretty good job and there are no shorts.
Also in step 3 of the build guide, it says to add 2 x 10k resistors that were blue with colour code: Brown, black, black, red brown. I had received a different set though. These were not blue but the same colour as the rest with colour code of gold-orange-black-brown...but I believe these are the same so I wouldn't think this makes a difference.
I don't know if this matters either but one of the resistors may be facing the wrong way around and I had to desolder one of the electrolytic capacitors to change direction.
Where do I go from here? I'm not very electronic savy so I would be grateful if someone could give me some advice on what to check.
I can then proceed to add the RFM module, the antenna and the ATmega328.
Thanks in advance.
Darren
Re: emontx voltage check
You appear to be putting a seriously high voltage on your emonTx. How are you powering it? The usual way is either with a plug-top USB power supply and lead to the USB connector, or via the programmer and your computer's USB. Both should give you nominally 5 V and no more than 5.25 V anywhere on the board.
The other possibility is your meter is faulty. What voltage do you measure across a 1.5 V battery? And your car's 12 V battery?
Don't continue with your build until you have resolved this.
Don't worry which way round the resistors are - it doesn't matter (I just looks more professional if they all face the same way!) It also doesn't matter for the small-value ceramic capacitors. It does matter for most of the other components.
Your 10 K resistors are fine. The ones you have are 5% tolerance (the last colour - gold - is the tolerance, you read it from the wrong end, the one described was 1% tolerance).
http://en.wikipedia.org/wiki/Electronic_color_code
Re: emontx voltage check
Hi Robert,
I'm just powering it through the mini usb port on the emontx which is connected to my laptop.
I checked a 1.5V battery and it showed 2.4V so obviously it must be the digital multimeter I'm using. I failed to mention that the black lead had come out of the probe - surely that must be it. I have like a DIY fix on it at the moment but maybe I need a new set of probes.
Re: emontx voltage check
I think you were measuring pick-up from somewhere. You must keep your test gear in good order, otherwise you're lost. But there's a serious warning here: What would have happened if you had tested a live mains circuit and your meter had shown it was safe? At best you could have had a nasty surprise; at worst, a fatal shock. Always check your equipment before relying on it. You could have proved your probe was faulty by bringing the two probes together and measuring Ohms - anything other than zero and you have a problem.
Re: emontx voltage check
Oh of course, yes I know. I did borrow it off a friend though and considering this was only a small circuit board I thought I would just give it a go to see.
Thanks for advice anyway Robert.
Hopefully it will be okay when I check it again, otherwise I might have to call on your help again;)