dummy load kit - Page 1
Forum section: electronics / general

author: electronics man
author_rank: Frequent Contributor
timestamp: January 27, 2014, 06:30:32 pm
content: i was thinking about doing a "some assembaly required " dummy load kit. it would be based around the atmega328 so it can be programed in arduino so the user can develop it and change it to there requierments. it would use a presision opamp, darlington transistors and power resistors. this is just one of many ideas i have had. i would like to know what you think plees give feedback.

author: dr.diesel
author_rank: Super Contributor
timestamp: January 27, 2014, 06:44:49 pm
content: You should absolutely do it, nobody does a half decent load kit that I'm aware of.

author: phil
author_rank: Regular Contributor
timestamp: January 27, 2014, 07:53:32 pm
content: Sounds good. I had similar ideas a while back, but there are always legal problems with selling electronics in germany (WEEE regulations are really harsh here for small companies).Be careful: If you plan on selling your kits in europe, make sure to evade WEEE where you can (every country has it's own regulations!). If you don't, you have to register in every country you plan to sell - that will cost you a fortune.I don't know how bad it is in GB or other european countrys, but germany is a though one if you sell anything else than complete DIY kits. Even half assembled boards might be a problem.Phil

author: ciccio
author_rank: Frequent Contributor
timestamp: January 27, 2014, 08:34:03 pm
content: WEE regulations (and CE safety regulations, too) and required bureaucracy work are a nightmare, but I'm not sure that it can be applied to a kit or a device bought outside Europe by an individual for his own, personal, use.All this Chinese stuff we buy on Ebay or on Internet shops has no documentation, or has a fake documentation, and there is no "importer" in the UE to sign a certificate of compliance, but I have no evidence of parcel seized or confiscated at custom or at post offices. They usually run over big deliveries (like a container full of thousand of Christmas tree lighting chains that were dangerous by only looking at them, so low was the insulation and the creepage distances).Edit: I see that the OP is in UK, so what I wrote does not apply (legally), but most of the small companies I know do not care of WEE and CE compliance, at least if there is no evident interference with other devices...Maybe this is sad (admitting diffuse non-compliance with law) but is a reality.Best regards

author: phil
author_rank: Regular Contributor
timestamp: January 27, 2014, 09:00:26 pm
content: It has no effect for a single person, yes. But as soon as you import stuff to sell it (or even give it away!!), you are a manufacturer (at least according to german law). That means, you are bound to the WEEE regulations and have to follow them. The penalties for not doing so are quite severe, I wouldn't recommend trying.If you are outside europe and sell your stuff to persons in the EU -> no problem.If you are within europe and sell your stuff to persons in the EU -> WEEE hits you in the face.As I said, I don't know the rules in other countrys. Allow me to use german laws as an example (all figures for less than 1000kg products sold/year, if more, it will cost you way more):Selling, renting, gifting (!) of any electrical product that falls under WEEE regulations (doesn't matter if imported or your own product) is prohibited if you do not:- register your product with the "Stiftung EAR".- tell them how many kg of electronics you sold/gave away (every month!)- recycle containers full of electrical waste based on a lottery system (of course, you pay for all costs! Usually, thats about 1000-1400€)You have to register every single product type you sell. Depending on product type and other things, a registration costs about 300€ once and then 220€/year.There are companies that offer some kind of insurace against all this. You pay them a yearly fee and they take care of all that stuff for you (recycling included). But even so, this can be as high as 500€/year - for one product. If you sell two different products, well, you have to do all this for EVERY product type you sell.If other countrys have similar laws... you would be better off avoiding this WEEE stuff where you can!The only loophole I know of is to sell components, not products. If everything you sell is just a component, they can't touch you. But as soon as you sell anything that has a function on its own, its over.Of course, CE is another thing entirely - don't get me started on that.However, all this stuff only applies to sellers, not buyers. As long as it is for personal use, you are fine. But importing electronics without CE conformity can cause issues with customs - at least in Germany.Edit: ignoring WEEE and CE may work out, but if you are found out, you better have good lawyers and a LOT of money. Ignoring WEEE can cost you 100 000€ and more in Germany. In any case, that would be the end of any small business. CE does not mean you have to get your device tested, it only means you have to be sure it would pass the tests and state that in an official document. Of course, your competitors could test you product - if it fails... well, same as above. You are in deep shit. Same thing with WEEE, any competitor could sue you. Sadly, thats common practice today.Phil

author: electronics man
author_rank: Frequent Contributor
timestamp: January 27, 2014, 09:19:48 pm
content: mabe i could only sell inside of the ukand a question: if i sell it partly complete but no one bit is working when during shiping is that ok.

author: dexters_lab
author_rank: Unknown
timestamp: January 27, 2014, 09:30:02 pm
content: Quote from: electronics man on January 27, 2014, 09:19:48 pmin all honesty, i really would not worry much about this

author: phil
author_rank: Regular Contributor
timestamp: January 27, 2014, 09:46:33 pm
content: Quote from: dexters_lab on January 27, 2014, 09:30:02 pmIgnoring this now won't help you. Read the laws in your country, get some information and decide if you have to worry or not. But do NOT ignore it without getting some information first. Also, get some info regarding the packaging rules in the EU, might cost you money, too.Just prepare yourself before you start a business or you might regret it later. Taking risks without knowing what can happen is just stupid.Phil

author: electronics man
author_rank: Frequent Contributor
timestamp: January 27, 2014, 10:04:20 pm
content: it seems a bit much for me and i dont realy have the time or the money

author: phil
author_rank: Regular Contributor
timestamp: January 27, 2014, 10:28:54 pm
content: It's more about time, not money (if you are clever).First thing would be to find out if your product falls under WEEE rules. If not, forget WEEE. If it does, change your product until it does not.Next thing, find out about taxes and stuff for crowdfunding. That way, no nasty surprises aferwards.After that, think about shipping. Depending on local laws, crowdfunding is either a commercial thing (packaging recycling laws apply!) or a donation followed by a gift.I am not sure about CE, but I think it won't concern you, because CE conformity depends a lot on build quality. If it is a kit, you don't build it up - no CE for you. Double check that to be sure.Please, go ahead with your project, I really like the idea. I may do something similar soon together with a few other arduino based products. Just make sure to know your laws or some douche could ruin it for you.Take a lookhereto find out which rules might concern you. They offer solutions for these problems (way too expensive for a small business) and can answer some of your questions. Just remember when you ask them: They will try to sell their services.Phil

author: sleemanj
author_rank: Super Contributor
timestamp: January 28, 2014, 12:41:18 am
content: Putting aside the boring legal mumbo for the moment.I think there would be a good market for a dummy load kit, a good one. Just look at uCurrent for a fairly niche product that sells well.It's something I'd personally be interested in, but I'd want:LCD showing all pertinent measurements (a 2 line character LCD would be all that's needed)Must have constant power modeMust be able to sink about 35 Watts comfortably (with forced air is OK if necessary)Must handle about up to 30 VoltsMust handle at least 5 amps (within it's power capacity)Must be protected in the various sensible ways (over temp, over current, over voltage, under voltage (these should all be settable via the UI), reverse polarity...)Must have data output (serial, SD card... some means of logging data into a csv file anyway)Ease of assembly, if SMD no 0402 parts etc, in fact I'd stick with 1206 for maximum ease (I'd go through hole only where necessary or if there is a cost saving)Should not use "exotic" parts, keep as much "jellybean" as possible.

author: phil
author_rank: Regular Contributor
timestamp: January 28, 2014, 08:26:16 am
content: Sounds good. In addition to that I would want a SCPI compatible PC interface.For dynamic tests:- Switch between 2 current settings with at least 120Hz, better more, i.e. 400Hz.- Trigger output for that current change to view response on a scope and an external trigger input for automated testing.- A good voltage and current readback is important, too. Multiple voltage/current ranges to make good use of your ADC/DAC resolution (at least 12bit).Modes of operation should be: constant U/I, constant R, constant P.A good dummy load is a fair bit of work and will have it's price.Phil

author: psycho0815
author_rank: Regular Contributor
timestamp: January 28, 2014, 02:19:59 pm
content: I'm actually working on something similiar at the moment so i might actually steal some of the ideas here.I was gonna base it on the arduino as well, but reading about alle the ideas here i'm thinking maybe something more highlevel would be better.Like maybe the Arduino YÚN. You could have the Atmega handle all the low-level stuff like interfacing with the DAC and ADC and the ARM handles high-level input. That would make it very easy to do stuff like datalogging directly to an usbdrive, webinterface, scpi and pretty graphics.As to the OPs original question, i think it's a cool idea, but it would propably be too much hassle to be worth it, legally. especially in the eu, where there are loads of regulations with loads of exceptions and exceptions to the exceptions and so on.Might be easier to just sell the bare pcbs on ebay or talk to some of the maker-oriented distributers if they might be interested in cooperating with you.

author: phil
author_rank: Regular Contributor
timestamp: January 28, 2014, 05:24:27 pm
content: The idea itself isnt't new, so it's hardly stealing anyway. There is actually a great dummy load kit available, but it is quite expensive and part of a complete DIY lab system. Finished products involve too much legal stuff inside the EU, yes.If you aren't sure that you will sell >10 000 of them, don't bother with it at all. Kits are the way to go here. But there are many legal issues even if you sell only kits. Thats the EU for you: If you can't bribe enough officials yourself, you will have a hard time againtst those who can.That being said, I plan to release a similar dummy load as well. Seems to be a popular ideaPhil

author: dr.diesel
author_rank: Super Contributor
timestamp: January 28, 2014, 05:31:45 pm
content: Quote from: phil on January 28, 2014, 05:24:27 pmComplete DIY lab? Link please.

author: psycho0815
author_rank: Regular Contributor
timestamp: January 28, 2014, 05:36:57 pm
content: that stealing thing was a joke.Do you mean the ct-lab kit?http://www.heise.de/ct/projekte/machmit/ctlab/wiki? i've thought about it, but it is rather expensive, might still be worth a second look.As for the popularity i think there are multiple reasons.- dave did a video on it- the basic principle is really simple and it's also easily expandable to include all the features you need/ can be bothered to implement- professional ones are expensive enough to justify a diy solution.- it is in fact a useful piece of kitthat's just my 2 ct anyway

author: phil
author_rank: Regular Contributor
timestamp: January 28, 2014, 05:45:01 pm
content: Exactly, the CT labs one. There is an unofficial wiki that lists all available moduleshere.They use very expensive and hard to get components, but the performance is really good. A DIY kit based on these modules might be possible. They offer some serious stuff that a hobbyist wouldn't really need so you can cut the price a bit.Of course, all kits developed with CT labs as base have to be open source - but you can't keep kits closed source anyway, so thats a given.I think there is even a market for two or possibly more seperate designs as the price can easily range from 30€ up to 130€, depending on features and accuracy.Phil

author: electronics man
author_rank: Frequent Contributor
timestamp: January 28, 2014, 05:50:25 pm
content: My plan is to make it fairly accurate (using high precision rail to rail opamps) so that would put the price up a bit and also my costs would be high so it would probably cost around £50 (don't hold me to that)

author: electronics man
author_rank: Frequent Contributor
timestamp: January 28, 2014, 06:10:33 pm
content: Quote from: psycho0815 on January 28, 2014, 02:19:59 pmDo you know of any companies

author: psycho0815
author_rank: Regular Contributor
timestamp: January 28, 2014, 06:17:03 pm
content: Quote from: electronics man on January 28, 2014, 06:10:33 pmthe one that comes to mind in the eu would be watterott.com.apart from that no, sorry

author: Icchan
author_rank: Regular Contributor
timestamp: February 05, 2014, 12:43:54 am
content: You should do it. My current project requires something that could sink around 5-10 watts of power for testing and characterizing my DC/DC converter and battery charging and wireless power thingies and to find out the total power usage of my final device since it's battery powered. For that I have purchased some very large and heavy duty gear and I think I shouldn't need to do that for something so small.There used to be a dummy load on iTead (if I recall right) that would have been perfect, but they don't sell that anymore. Ebay was no go (didn't find any small ones) and so I'm either going to have to do myself or buy a high end ones from Agilent or Hp... and since I don't want to start a meta project to get this one onwards, Agilent/HP it is... but I really shouldn't need to do that.Please do this project and I'll be one of your customers when it's out