Need Chinese designer/manufacturer of power supplies - Page 1
Forum section: electronics / general

author: ocset
author_rank: Super Contributor
timestamp: April 06, 2019, 06:11:06 pm
content: We have designed a fog detector for roadways…it’s a power supply which charges up to 300V, then flashes over a bank of IR LEDs…..this pulse is received by the detector…if it isn’t received, then it means there’s too much fog in the way.Thing is, there is no offtheshelf power supply that does this charge up to 300V then flash over (where it discharges down to ~50V every second) , so we need a Chinese designer/manufacturer.Which “go-between” company in UK (or Europe/Aus or USA) can we contact to get through to a reputable Chinese designer/manufacturer of power supplies?

author: CM800
author_rank: Frequent Contributor
timestamp: April 06, 2019, 06:23:49 pm
content: I'd suggest doing it inhouse, just a simple boost converter, it sounds like you won't need to trigger it that often (only once every 10 seconds - few minutes.)So either a boost converter like many have used for coilgun charging, or maybe a copy of a disposable camera flash charger. Will save you a lot of cost putting everything on your same control board.LT have some nice chips too:

author: StillTrying
author_rank: Super Contributor
timestamp: April 06, 2019, 06:49:34 pm
content: I thought fog was transparent to IR.

author: ocset
author_rank: Super Contributor
timestamp: April 06, 2019, 07:08:03 pm
content: Thanks, yes , it may be UV or blue light , i will re-check

author: IanB
author_rank: Super Contributor
timestamp: April 06, 2019, 07:12:42 pm
content: Every disposable film camera with flash has (had) a little power supply inside it that charges up to 300 V. Although they are a bit obsolete now, there were dozens of designs of such power supplies that were produced by the million. Find one of the companies that designed them?

author: dmills
author_rank: Super Contributor
timestamp: April 06, 2019, 07:27:44 pm
content: Self osc flyback to charge the cap, then a diac, or (OLD school) a neon lamp to trip an SCR when the cap reaches a high enough voltage....Probably about two transistors, two diodes, one SCR and a neon lamp, job done?Actually these days I would probably use a little 8 pin micro to both produce the switch gate drive and the trigger pulse for the SCR, less parts and you can do neat things like program sleep times between pulses as well as maybe providing for some BITE via a photodiode and some sort of dumb fault indicator.As to getting a Chinese design, start with a really detailed spec, and find someone who (ideally natively) speaks the language and knows the culture to help with this, I have someone I use, but it is a personal contact. Expect to have to send someone out there a few times to get issues resolved.Regards, Dan.

author: m98
author_rank: Frequent Contributor
timestamp: April 06, 2019, 10:32:20 pm
content: treez, you can't be serious. You roam around this forum complaining about companies outsourcing their electronics design and manufacturing to China and that its your life's dedication to design LED drivers, but now you have no idea how to design relatively simple power electronics and want to outsource a part of a road safety device(?) to China?</rant>

author: Brumby
author_rank: Unknown
timestamp: April 07, 2019, 12:57:40 am
content: Quote from: IanB on April 06, 2019, 07:12:42 pmSome years ago I went through a phase of collecting those disposable cameras from photo processors and pulling out the flash board. They run off a single AA battery. I still have a couple of hundred of them.Interested? .... Make me an offer.(Batteries not included.)

author: ocset
author_rank: Super Contributor
timestamp: April 07, 2019, 10:11:09 am
content: QuoteWe must go to China, as otherwise a competitor will take the power supply and do it with a cheaper Chinese version and blow us out of the market.Chinese power supplies have Chinese IC’s in them, which are some ten times cheaper than Western IC’s. And western engineers cannot design with Chinese IC’s because they only have Chinese datasheets….or datasheets that are only available in China.Not only that, but even if a western engineer learned Chinese and somehow got hold of the Chinese datasheets, it would still be useless , because the western engineer would not know the logistics behind any particular Chinese IC…so could end up designing in a chip that was always in low supply…or was more expensive than an alternative Chinese IC.Only a Chinese Electronics Engineer can use a Chinese IC.That’s why we have to go to China to get this done (or rather , get it designed and manufactured in China)QuoteWell Blueskull i suspect strongly that this is well below your level. We both know that in China there are loads of Engineers that could do a cracking job of this, and leave you to do the more juicy Power elec projects, that pay you the more money that you deserve.

author: Ice-Tea
author_rank: Super Contributor
timestamp: April 07, 2019, 10:52:57 am
content: My 0,02$:This does not fall in the "give me a 75W, 12VDC COTS PSU" category. Which means you'll be asking them to do actual engineering for you. This means that you'll have to give them a *lot* of design specifications or they'll make you something that fits the limited design set you give them and fails everything else (think ridiculous inrush currents, 5% efficiency, EMI through the roof, not shock proof,...). You can assume that whatever you don't specify will be done according to the "But it works (Now. Kinda.)" philosophy. Don't specify the color of the PCB? You'll get pink if it's 0,0001$ cheaper. Don't specify component derating? You'll get components used at 100% or more.You're underestimating the time you need to put into this to get a good product. And you're overestimating the price advantage of "Chinese" components.In other words: unless you're planning to move tens of thousands of these, there's probably no point in pursuing this. Unless you don't care about quality.

author: chris_leyson
author_rank: Super Contributor
timestamp: April 07, 2019, 12:29:29 pm
content: ^^^^ What Ice-Tea just said.You haven't even gone through a list of available topologies like flyback, boost, current fed push pull etc.I wouldn't bother with a camera flash blocking oscillator, it's probably one of the worst topologies for all of the reasons Ice-Tea mentioned, inrush current, efficiency and EMI are just three reasons why it's a non starter. How many Watts output power do you need ? Probably not much as the load has a very low duty cycle, say 10W or 20W, you need to work it out. At that sort of power level I would go for a self oscillating BJT current fed resonant Royer. It a very simple and reliable power conversion stage much more reliable than a blocking oscillator. I've got a medium power CCFL driver that came out of a photocopier, it's current fed resonant Royer made by Harison Toshiba Lighting Corp and the transformer is wound on an EFD30 core so I should be able to squeeze 20W out of it. Just my 2 cents.EDIT: It's a Cannon lamp driver part number FH3-2217-000.

author: dmills
author_rank: Super Contributor
timestamp: April 07, 2019, 12:45:38 pm
content: Indeed, if you are making tens of thousands a year China kind of makes sense (But even then it is a pain in the arse in weird ways and you can look at at least a year or two to get the kinks out), but for less volume then that, not worth it!Lets see: We had extruded ally that was not ROHS compliant (Somehow), Earth terminals only done up hand tight, wiring (which it turned out the factory had subcontracted and not inspected) of shocking (literally) standard... Got it all sorted in the end, but man what a fight.Don't forget that the time difference also makes working with a design shop over there a pain in the arse, every query takes two days.Your BOM on something specialist like that should be a SMALL proportion of the selling cost, so why worry about component pricing? If COG is more then about 30% of selling price you are doing it wrong (And COG is generally two or three times the electronics BOM), highway kit is EXPECTED to be expensive.Regards, Dan.

author: ocset
author_rank: Super Contributor
timestamp: April 07, 2019, 02:53:27 pm
content: Thanks, by "COG" i take it you mean "cost of goods"....COG being less than 30% of selling price sounds like a big markup?

author: NorthGuy
author_rank: Super Contributor
timestamp: April 07, 2019, 03:25:15 pm
content: Quote from: treez on April 06, 2019, 06:11:06 pmEarlier you said you were a brilliant power supply designer who cannot find a job in UK. You can hire yourself!

author: StillTrying
author_rank: Super Contributor
timestamp: April 07, 2019, 04:30:46 pm
content: Why is 300V needed for LEDs.

author: ocset
author_rank: Super Contributor
timestamp: April 07, 2019, 06:23:43 pm
content: i must admit i havent revealed the full details..but there is one solution involving many in series

author: tggzzz
author_rank: Super Contributor
timestamp: April 07, 2019, 07:04:17 pm
content: Quote from: CM800 on April 06, 2019, 06:23:49 pmSplutter.I suggest you look at most of the other topics started by treez!

author: Kjelt
author_rank: Super Contributor
timestamp: April 07, 2019, 07:11:27 pm
content: Quote from: treez on April 07, 2019, 06:23:43 pmNor should you, not many companies like it when their employees leak sensitive new product info onto a public forum.My advice do not share application knowledge on front till you have the patent in your pocket and are allowed to share it.

author: dmills
author_rank: Super Contributor
timestamp: April 08, 2019, 11:22:10 am
content: Cost of Goods of 30% of factory gate price is fairly standard for electronics, a bit lower in small market professional kit (You have NRE costs to amortise over a smaller volume), quite a bit higher in mass market consumer where you are basically competing on price, and are doing big volumes. I generally warn my management if I see COG exceeding about 25% of factory gate, then they can take a view.Remember that all the engineering (including software) is an NRE cost, which has to be recouped, and you have things like buildings, and management, QA, sales, marketing (Different functions!), admin and janitorial staff to pay for that are not generally accounted in the COG.Also remember that the metalwork, and assembly costs factor into the COG, so your BOM should be significantly lower then the COG, I usually try to keep the electronics BOM < 50% of target COG.Seriously this stuff is business 101, it follows on from the "Sell things for more then they cost you" lesson.Regards, Dan.

author: chris_leyson
author_rank: Super Contributor
timestamp: April 13, 2019, 07:30:19 pm
content: As I need a small 15W to 20W adjustable power supply, 100VDC to 450VDC, to replace a $10 Chinese step up flyback that really isn't performing that well I thought I would try out a resonant Royer converter for a change. I re-wound the transformer on a CCFL driver that came out of an old Cannon copier and fired it up.200V pk-pk output for 7VDC input and 900V pk-pk for 30VDC input. Not bad for best guessing the number of secondary turns whilst holding the bobbin and wire in your hand. The resistive load is a 15W 230V light bulb and the transformer runs a little warm because the RMS primary current in the LC tank is about 3A. Reverse Vbe is about 9V which is a bit higher than the rated 6V for the 2SC5291 transistors so I need to tweek up the secondary turns and run at a lower input voltage.If you want 600V pk-pk output for 12V input then 100 turn secondary will get you pretty close with a 6+6 turn primary. Another improvement might be winding the high current tank inductor on a powdered metal toroid then you wouldn't need a gapped core for the transformer and you can use a higher number of turns.LTSpice model of converter attached below and it is pretty damn close to the real thing. It's maybe 75% efficient for 15W load but that can be improved by moving the primary tank and then you could perhaps use a cheaper EE25 core for the step-up transformer. EMC will not be a problem because it's a squeaky clean sine wave.For a power supply designer it doesn't look as if you've made much effort in terms of R&D and that is what you're paid to do FFS. EDIT: Sorry forgot to add Jim Williams AN118 go look it up. You can move the constant current feed choke to the emitters and regulate the emitter voltage to control the outpit voltage. The push push Royer design has been around for well over 50 years. Classic Royer and Jensen converters are squarewave flux controlled converters that rely on saturation. A prelude to resonant ZVS converters although the control method is different. You can always improve the efficiency by treating the converter a class E or EF amplifier by tuning the secondary and that comes from an RF engineering perspective. Resonant push pull oscillators have been around for a long time. A two transistor resonant converter you can't make it any simpler than that.

author: Jwalling
author_rank: Unknown
timestamp: April 14, 2019, 09:37:56 am
content: Quote from: tggzzz on April 07, 2019, 07:04:17 pmWhy does he thank every post? Yo Treez! Give me a high-five!