Product construction and AC power - Page 1
Forum section: electronics / beginners

author: Lowkus
author_rank: Regular Contributor
timestamp: March 19, 2021, 06:31:09 am
content: If a solo inventor is building a commercial product that gets power from a computer-style AC power cable, and the product only needs 5V and a little bit of amperage, does the inventor typically design the circuitry that pulls the correct energy from the power cable or is there a premade component that they would typically purchase?

author: fordem
author_rank: Regular Contributor
timestamp: March 19, 2021, 10:35:52 am
content: You can do it either way - as the "inventor" or product designer, the choice is yours - if by commercial product you mean you're designing a product to be mass produced & sold, the final choice will probably be dictated by the economics.

author: Lowkus
author_rank: Regular Contributor
timestamp: March 20, 2021, 04:45:32 am
content: Is C14 the name of that plug that feeds AC into computers? I've been programming for decades and never knew the name for it.For commercial cost efficiency in a retail destined product, is something like what blueskull posted going to be saving other unforeseen costs related to product safety? Like are there regulations about having certain isolation cages around the hot wires coming into the product? Maybe a better question would be, is there some sort of "Electronics Safety Regulations" guide that have to be followed before a product can be approved for sale in the U.S., E.U., Australia, etc.?

author: Lowkus
author_rank: Regular Contributor
timestamp: March 20, 2021, 05:49:36 am
content: Wow, lots of information there. I just looked up ISO62368-1, it's like $450 or something thereabouts! How do governments get away with hiding the safety standards behind a paywall? That's downright immoral.

author: mvs
author_rank: Frequent Contributor
timestamp: March 20, 2021, 10:26:41 am
content: Quote from: Lowkus on March 20, 2021, 05:49:36 amISO needs money to operate and its fully ok, if they get a bit from the companies, that are selling their comercial products internationaly.Local gouverments can give national versions of this documents for free, if they like. Russia does it for instance.Quote from: Lowkus on March 20, 2021, 04:45:32 amIEC-60320 C14 is a plug and C13 is a socket.Quote from: Lowkus on March 19, 2021, 06:31:09 amRecom solution is cool, but after a short cost calculation most of this solo inventors would buy certified external power supplies with 5.5mm barrel or USB connector. No supply at all is also a valid option (look at raspberry Pi for instance).

author: RayRay
author_rank: Frequent Contributor
timestamp: March 20, 2021, 06:04:57 pm
content: Well, you could use a cheap AC>DC 5v circuit board, but given the plug type, you'd need to handle the grounding part properly. Is the enclosure of the product gonna be made out of metal? Does the product have any external probes/handles (that are made out of metal)? And why not just use a plain AC-DC adapter instead? If manufacturing on a large scale, you could reach out to a Chinese company who manufactures em (and get a good deal for em!) and you could just get DC input jacks with panel mounting, I.E one of these:https://www.aliexpress.com/item/4001050150711.htmlhttps://www.aliexpress.com/item/1005001485034492.htmlBut if you've had the product already manufactured, then I guess you'll have to stick with the 3PIN computer type plug.

author: Lowkus
author_rank: Regular Contributor
timestamp: March 20, 2021, 07:11:33 pm
content: My plan right now is to build a synthesizer, I'm figuring on a metal chassis with wood cap ends, but if the thing weighs too much I might have to go with a plastic housing instead. I've always preferred a C13 power solution on music gear, it gets rid of the problem of losing the AC adapter, and C13 connections feel a bit tougher and more professional.

author: mariush
author_rank: Super Contributor
timestamp: March 20, 2021, 08:28:18 pm
content: If your device only needs one voltage (5v), it may make more sense to put a barrel jack connector or a usb power only connector on the device and use a separate power adapter.You could use a cheap LDO (linear regulator) to regulate a wide input voltage (7.5v..12v for example) down to 5v and that would allow you to bundle your product with whatever DC adapter you have available. DC adapters will be certified for the country you sell the devices in, and they're cheap...For example, 4$ + VAT for 5v 2A adapter with standard 5.5mm/2.1mm barrel jack if you buy at least 25 pcs :https://www.tme.eu/en/details/posb05200a/plug-in-power-supplies/pos/Here's 5/7.5/9v with 5.5mm/2.1mm barrel jack :long tme.eu linkOn Digikey, they're 5-6$ each in quantity :https://www.digikey.com/short/075jd29tThe barrel jack should be cheaper than a C13/C14 connector, can be mounted directly on pcb, so you save some money... You don't need to deal with high voltage inside your device, you don't need to bundle your device with a power cable that will be heavier than a ac-dc adapter / wall wart.There's also adapters that are universal, or on which you can clip different AC pinsQuoteIf you use a standard barrel jack or a type a or type c usb connector, who cares if you lose the adapter, one can buy another anywhere...You could mold / shape the back of the device to have a depression or something in which that person could press fit or slide in the adapter, so it wouldn't be lost.

author: wizard69
author_rank: Super Contributor
timestamp: March 21, 2021, 12:05:25 am
content: I might suggest that you have higher priorities than the plug type. First off you really need to consider your legal obligations and make sure you have a properly set up corporation. You put an AC plug in a device and you immediately elevate your legal exposure potential. Further if you don't have the engineering background you need to make sure the equipment will be safe in all likely use case which may require engineering assistance to meet regulations.If you where to make one synthesizer for your self you would not have nearly the problems that selling to the public at large creates. This is what makes so many ideas, often good ideas, so hard to get to market. You really need the protection of a corporation, good insurance and frankly access to a good lawyer. Then there is the paper work, quarterly filings and other non sense. Years ago I had some ideas and frankly I couldn't stomach the paper work and the huge out lay of cash that really does nothing for your product. Lawyers are not cheap, neither are accountants, insurance is hideous, and depending upon jurisdiction simple incorporating is a big expense.Here is a quick link to a bit of C14 info:https://www.interpower.com/ic/InfoPower/iec-60320-c13-c14.html.However the focus on the socket at this point may be premature. For a limited production item there are al sorts of options that can be installed behind the inlet connector. You can get inlets that integrate filtering or noise reduction, inlets that have fuses built in, or inlets with voltage selection mechanisms. Or in your case, MAYBE the right choice is an inlet that is part of a DC supply. How to best deliver your device is something you will need to work out and justify in court if somebody gets hurt.About that case, if your desire is a robust machine that can handle the rigors of being on the road, your only real choice is a metal case if you need a custom design. A good sheetmetal shop should be able to deliver affordable housings in reasonable production quantities. A decent "plastic" case would require hard tooling and that is a big expense. In low volume though it would be better to look for an off the shelf case that fits you needs.As for wood caps an weight both are a mixed blessing for the road. Plain wood will crack and split, You may be better off with plywood or another composite construct. As for weight, some people see that as an indication of solid construction. More importantly weight helps keep an instrument anchored during performances. The trick is to find the right balance. So don't sweat a bit of weight and seriously consider construction out of metal. That is as long as it makes sense for the use cases envisioned and is compliant with regulation.Quote from: Lowkus on March 20, 2021, 07:11:33 pmThat is fine until you can't fine the mating cord. Sometimes i makes more sense to supply the instrument with a long cord attached with a cord grip. If you do go with an inlet consider a cord retainer. There is not perfect answer here, I find IEC connectors to be a mixed blessing.

author: Lowkus
author_rank: Regular Contributor
timestamp: March 21, 2021, 12:21:09 am
content: Are there liability worries from the possibility a consumer will open the chassis and then get electrocuted while they're poking about? Or is the concern that bad design will cause the chassis or socket prongs to become charged enough to cause an injury while the consumer is simply using the product as normal? It seems like a judge would not side with a party that was poking around inside of an electronic device, but then again the judicial system doesn't always follow a logical path.

author: mvs
author_rank: Frequent Contributor
timestamp: March 21, 2021, 11:32:12 am
content: Quote from: Lowkus on March 21, 2021, 12:21:09 amYou will need to mark hazard properly and write an user manual with all possible precautions, like "do not put your cat inside".QuoteBad design can be an issue and appart of a direct injure there might be other problems, like an overheating / a fire hazard, etc. Even if you use a certified power supply in your design, there might be some problems and you may need to make a recall.

author: RayRay
author_rank: Frequent Contributor
timestamp: March 21, 2021, 01:17:56 pm
content: Quote from: Lowkus on March 20, 2021, 07:11:33 pmIf you'd use C14, regardless of the chasis material, you're gonna have to take care of the grounding, which would would increase the manufaccturing costs. For this one, I think you'd be best going with a plastic chasis along with a DC jack. 5.5*2.1 or 5.5*2.5 are standard DC jack sizes (and it'd be very easy to find a replacement AC adapter if the original is lost) but how many amps approx would it consume? I may have some additional ideas.

author: Lowkus
author_rank: Regular Contributor
timestamp: March 21, 2021, 09:47:03 pm
content: I'm not sure how many amps yet, I'm just taking the first step on the journey.

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 22, 2021, 01:39:44 am
content: Perhaps it has been stated clearly but I did not see in reading the thread.For a product marketed in the US, if it has 120 Vac or greater brought inside the chassis, the product needs to be tested by a Nationally Recognized Testing Laboratory (NTRL). This is typically UL although there are others. This can be a major pain and expense. Time, money and the frustration of dealing with a non-negotiable entity that sets its own arbitrary rules can be at times worse than dealing with government.Power it with a wall wort that outputs lower than (IIRC) 50 volts, and the need for NRTL approval falls to the builder of the wall wort. Usually. You can find some details on OSHA’s website.https://www.osha.gov/nationally-recognized-testing-laboratory-program/products-requiring-approvalIf the unit has microprocessor of any kind, it will need FCC certification. That could be for WiFi or any number of reasons, the most common reason is called an “unintentional radiator”.https://en.m.wikipedia.org/wiki/Unintentional_radiatorExporting to other parts of the world has area specific requirements which is another, different discussion.As wizard69 points out, there are many reasons why many products never make it to market. One the ways that some try to avoid all the costs is to sell the product as a kit. That can sometimes work, it depends on the target market. Of course lawyers will tell you you can never escape liability.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 22, 2021, 01:46:24 am
content: Quote from: blueskull on March 19, 2021, 06:40:19 amUnderpowered for something like RPI4.

author: jmw
author_rank: Frequent Contributor
timestamp: March 22, 2021, 02:35:31 am
content: Quote from: Lowkus on March 20, 2021, 07:11:33 pm+1 to starting with a barrel connector. They're cheap, lightweight, and will save a ton of space compared to a C13 power entry. Also +1 to not overthinking this. If you end up taking this through prototyping to a go-to-market team, the result will end up looking a lot different than what you started with, just from all the constraints that come from manufacturing.

author: peteru
author_rank: Regular Contributor
timestamp: March 22, 2021, 03:55:12 am
content: Quote from: Lowkus on March 20, 2021, 07:11:33 pmThen use a power delivery system that is standard in the industry and will be expected by nearly all your customers. An external 9V DC power supply with 5.5/2.1mm barrel connector, centre negative. That way you will be able to use the many power supply systems that are used by instruments and pedals. It'll also save headaches with ground loops.