Hello,
Is there a comprehensive component list available for each of the emon devices? The best I could find was the list of parts on the build guides (for instance, the emonTx one here). While useful, the list does not state the tolerances or power ratings for all of the components.
The reason I ask is that I have access to almost all of the components required to build these devices, but I don't know which ones to use. In particular, the capacitors listed for the emonTx, such as the 0.1uF ceramic ones - what sort of capacitance tolerance, voltage rating and so on would be required?
Also, if the folks who run the shop here use Farnell to order parts, would it be possible to list the part numbers? The place I have access to uses them as a supplier so it would be easy for me to find the required parts.
Cheers.
Re: Comprehensive Component List?
Take a look here:
http://solderpad.com/openenergymon/
Re: Comprehensive Component List?
Thanks, but I had found that already, and it only lists the components and their values, and not their tolerances etc.
Does the fact that the values I am looking for are not listed on the website mean it doesn't really matter? Can I just go for standard components as long as they have the correct resistance/capacitance/etc.? For example, I think the typical resistor tolerance is usually 1%. Is a typical capacitor tolerance more like 10%?
Re: Comprehensive Component List?
Can anyone just tell me if it's ok to use 10% tolerance capacitors in the emon devices?
Re: Comprehensive Component List?
Apart from the timing capacitors around the crystal - C6 & C7 - which need to be fairly precise, all the capacitors are for decoupling so any reasonable tolerance should be OK. You'll probably find that the worst you can get at 22pF will be 5% anyway. For the decoupling capacitors, you are more likely to be constrained by the physical size and fitting the parts into the pcb - hence voltage rating will be more important.
Most of the EmonTx circuit is lifted from the Atmel application note AVR465, and there's a components list there with (old) Farnell order codes. If you have an old Farnell catalogue, that should give you the information.
(The developers are busy with the design of a new EmonTx, so I guess posting a components list for the (obsolescent?) design is not a priority).
[Edit]
You are incredibly lucky. I've found a 1992 Farnell (paper!) catalogue. The capacitors specified by Atmel are Low K, 18 pF 2%, 100 V. Those supplied with the EmonTx kit are 22 pF. See here http://uk.farnell.com/multicomp/2222-680-34229/capacitor-22pf-100v/dp/11... If you have good contacts with Farnell, I'm sure they can recommend a suitable substitute.
Re: Comprehensive Component List?
These are the 10uF capacitors we use: http://uk.farnell.com/rubycon/25ml10mefc4x5/capacitor-10uf-25v/dp/8126380
100nf: http://uk.farnell.com/vishay-bc-components/k104k15x7rf53l2/capacitor-100nf-50v-x7r/dp/1469310?Ntt=1469310
and 22pf: http://uk.farnell.com/vishay/k220j15c0gf53l2/capacitor-22pf-50v-np0-radial/dp/1141760?Ntt=1141760
They are just standard capacitors nothing special you should be able to get some from any component distributor.
Re: Comprehensive Component List?
Thanks a lot Robert and Trystan, you've both been a great help.
Robert, I was unaware that a new emonTx was being developed - is there a page detailing the new features it will have? And a timescale? Should I hold off buying the components until after the new design is released?
Cheers.
Re: Comprehensive Component List?
That depends on your timescale. It will be SMT and is still at the prototype stage. See here: http://openenergymonitor.org/emon/node/736
Re: Comprehensive Component List?
Ah ok, I'll probably stick with the current designs and maybe build another when the new one is released.
Thanks for the help.