3 phase High voltage ac to low power 5V dc out

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1. Have 3 phase ac input with neutral, where each phase voltage goes from, 85V-600Vacrms

2. Need output at 5V/500mA

3. I was checking it:  https://www.st.com/resource/en/a...

its page 8 has this, that is to make dc from 3 phase

 

I checked ST/s VIPER267K, which has BVDSS of 1050Vdc .

But at full 600V each phase, the output dc after diode, can go upto 1100V (simulated on mulltim)

 

4. https://training.ti.com/sites/de...

page 22 shows external fet operation, but again limited to 1200V, very close, so cant use

 

5. Anyone have experience in this low power application where size/size constraints? Any reference design?

ST Viper could have used without transformer(its sealed application). but again breakdown voltage too close.

 

 

 

 



 

 

 

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Vindhyachal Takniki wrote:
2. Need output at 5V/500mA

This is what they make transformers for, you only need a single phase to ground if your 3 phase is delta, or to neutral if 3 phase is Y, look for a transformer with an 8v output to feed your rectifier and your regulator.

 

Jim

 

 

 

(Possum Lodge oath) Quando omni flunkus, moritati.

"I thought growing old would take longer"

 

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Vindhyachal Takniki wrote:

1. Have 3 phase ac input with neutral, where each phase voltage goes from, 85V-600Vacrms

2. Need output at 5V/500mA

 

That's a princely 2.5 watts, since you do have neutral, why not simply connect any generic 5V USB charger to a normal single phase mains ? (ie just pick one phase wire)

 

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Who-me wrote:
generic 5V USB charger

Vindhyachal Takniki wrote:
85V-600Vacrms

BANG

 

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1. Have 3 phase ac input with neutral, where each phase voltage goes from, 85V-600Vacrms

2. Need output at 5V/500mA

That's a good entry for the most ridiculous supply of the year...just pick a phase and get your 5V from one.  Are you worried one phase might go out? You don''t mention where it floats realtive to anything else.   Do you really need 500ma?  If you can use less, you  might have more options.

 

If you feel you can't just use a transofrmer & bridge/cap/regulator (easiest), you can use  something like:

 

https://eepower.com/news/85-to-4...     ....they have 900V devices too.  

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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A BIG part of the problem is the range of the mains voltage (85V-600V RMS). What I would suggest is a 600V-48V transformer, from any single line to neutral. The power is so low that inbalance between the phases should be almost undetectable.

 

At low line, this transformer would produce 48V * (85V/600V) = 6.8V. Rectify this and you will get about 68V to 9.5V. The upper end is a bit high but this can certainly be handled by any of several switch mode buck converters, especially at the 2.5W level that was mentioned. The 9.5V is quite sufficient to be bucked down to 5V. This would NOT work well if the transformer nominal output is 600V to 24V. 

 

That is my suggestion.

 

<EDIT> WARNINGs that should have been included above...

 

A. 600V is not just hazardous. It is potentially lethal. Do not do any design, installation, or maintenance on 600V side without the oversight of someone who is  experienced in the art. 

 

B. Anything that you build or use should be isolated. That isolation should be able to withstand twice the PEAK line voltage.

 

</EDIT>

 

Jim

 

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Last Edited: Thu. Sep 24, 2020 - 10:32 PM
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1. Yes if its single phase 85V-600Vac, I can use VIPER267K from ST (1050V BVDSS).

 

2. If I use like this to make dc from all three phase with neutral what would be peak dc at out?  Multisim simulation shows would go to 1100Vdc when each phase at max 600Vac?

I think it would be less, no peak dc should remain no?

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as already said, when you deal with 85-600V 3 phase you are not going to draw just mA's from that .

Take 1 phase to neutral, add a transformer to lower the voltage and then use a SMPS to make your 5V.

5V/500mA is 2,5W  @85V 2,5W gives a current of 29mA  at 600V even just 4mA. With motors doing 100s of mA's it might be just a little imbalance on it.

 

now before you start tinkering with lethal voltages ( even the 85V will be lethal depending on the fuse level) go and read on design standards you need to follow to get a safe product.

Even if you just do a one of in this case you need to make sure that you understand the rules and regulations as you still want to make a safe product.

Keep in mind you might be carefull, but someone else might accidentally get involved or you have ahd a bad night sleep and you get into trouble really fast ( faster than a quick blow fuse will react)

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1. Yes easy to use by single phase and neutral.

 

2. But if I use like this? The output dc will go to max 850Vdc?  

Advantage is here, if one phase get missing/broken, system keeps on running.

 

 

 

 

 

3. After that dc out, can i use VIPER26K, used ST-edesign suite, and put these inputs:

a) Vin: 85V to 600Vac

b) Vout: 5Vdc/0.47Amps

 

 

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Wear gloves (not cotton)!

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Beware that schematic.

 

It shows two separate grounds, one on the power side and one on this output side. It does not show any connection of the switcher to  EITHER ground. Also, that system does not appear to be isolated in any way. 

 

Isolation is one of the huge benefits of a transformer. I would not allow any equipment powered by that power supply into my shop!

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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Advantage is here, if one phase get missing/broken, system keeps on running.

And just how often does that happen?

 

And if it does happen, does everything else go to hell, or is the system supposed to keep functioning?

 

Planning for partial system failure can be very reasonable, but make sure the failures you are considering actually happen, and that they won't otherwise shut down the system anyways!

 

JC

 

 

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is the selection of varistor ok?  600Vac is absolute max in system.

https://www.digikey.com/product-...

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Vindhyachal Takniki wrote:

5. Anyone have experience in this low power application where size/size constraints?

 

I'm confused as to why you need a transformerless design and why you are space constrained?

 

You have lots of power available so I fail to see the need for transformerless, and correctly sized input connections and creepage/clearance distances will render any space saving moot.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

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Need to make something like this only.

1. This have Ultra-wide range: 90–600 VAC or 60–870 VDC  . In my case 600Vac is worst case max with all the error margins. 

2. very small form factor.

3. I think i can convert three phase  to dc with max 850Vdc at the output (post#9, image 1), resutls checked in multisim simulation not in reality.  

4. Diff is that its 15V/0.1mA, I need 5V/500mA for that ST Viper267K would work . 

5. Here varistors are not added, I want to add varistor to each phase/neutral also, so checking which can suit best.

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Brian Fairchild wrote:
I'm confused as to why you need a transformerless design

 

Transformers with primary windings rated to 600Vac worst case are a bit specialist perhaps.

 

Several bog-standard transformers in series might do it though.

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The 600Vrms requirement is difficult to meet.

The following module (isolated, 5V, 5W, 100Vrms to 480Vrms nominal, 528Vrms max) may need a voltage limiter :

RAC05-05SK/480 RECOM Power | Mouser

 

"Dare to be naïve." - Buckminster Fuller

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Brian Fairchild wrote:
correctly sized input connections and creepage/clearance distances will render any space saving moot.

+1000

I don't think the OP has considered this requirement for such HV, and it goes double for HVDC!

I see little or no space savings with this circuit!

 

Jim

 

 

 

(Possum Lodge oath) Quando omni flunkus, moritati.

"I thought growing old would take longer"

 

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"Dare to be naïve." - Buckminster Fuller

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I could see this power supply being the fuse for a massive arc flash event.  Fuse as ignition, not as protection.

Letting the smoke out since 1978

 

 

 

 

Last Edited: Sat. Sep 26, 2020 - 11:57 PM
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here you go....it's not just good, it's banggood

 

https://www.banggood.com/SANMIN-...

 

https://www.indiamart.com/prodde...

 

low voltage

https://www.nxp.com/products/pow...

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Sun. Sep 27, 2020 - 07:18 AM
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avrcandies wrote:
here you go....it's not just good, it's banggood

Agreed - That should be good for a bang.

 

The thing is tiny - I can't believe adequate clearances are maintained. Nor can I see any spark gaps.

 

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Nor can I see any spark gaps.

There is certainly a spark gap & you will see it once things are hooked up cheeky  ....bzzzzzz....bzzzz.....bam

 

Actually, it's pretty amazing how small the sizes are for under 1 KV...I hate when PCB guys lay out traces only 75 mil (or whatever) spacing for line voltage, but the visually small separations do meet the ratings. 

Give me 1/2 inch, and I'm a lot happier. 

 

 

 

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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digitalDan wrote:

I could see this power supply being the fuse for a massive arc flash event.  Fuse as ignition, not as protection.


+100

 

(Possum Lodge oath) Quando omni flunkus, moritati.

"I thought growing old would take longer"

 

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It should be obvious, and it certainly will become obvious when one powers it up if it wasn't previously so, but one also has to be aware of any node to node voltage differences and their clearance.

 

This dummy load is designed for up to 4 - 5 KV x several mSec loads, but the intra-nodal voltages are much smaller within the circuit, hence their smaller footprint than that of the input terminals.

 

JC

 

 

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1. I have a schematic here, attached

 

2) I have put these specs in e-design suite from ST

Vin: 85V-600Vac

Vout: 5V/470mA

It generates below diagram: But I have below queries



3) The arrow sign marked in red, how is digital low power ground connected here? How will i et 5V at the output then?

4) Also do high power ground and low power ground need to be shorted (marked by green box) . Data-sheet of VIPER26K says it should.?  (asked ST forum also let see)

 

 

 

 

 

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They are the "same", they are showing that you need to keep the clean grounds connected & somewhat separated from the noisy gnd (especially when using traces vs full planes), yet they also need to join together.

 

Imagine having a nice big bar of copper connecting the 3 earth gnd points shown...that would be extra-nice, bt you will probably use your pcb instead.

 

you may find this link interesting

https://incompliancemag.com/arti...(Figure%201).&text=Here%20are%20the%20precise%20IEC,nor%205019%20is%20explicitly%20stated.

 

Separate signal from power tracks. Generally, traces carrying signal currents should run far from others carrying pulsed currents or with fast swinging voltages. Signal ground traces should be connected to the IC signal ground, GND, using a single “star point”, placed close to the IC. Power ground traces should be connected to the IC power ground, GND. The compensation network should be connected to the COMP, maintaining the trace to GND as short as possible. In the case of two-layer PCB, it is good practice to route signal traces on one PCB side and power traces on the other side

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Mon. Sep 28, 2020 - 02:56 PM
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Vindhyachal Takniki wrote:

3) The arrow sign marked in red, how is digital low power ground connected here? How will i et 5V at the output then?

4) Also do high power ground and low power ground need to be shorted (marked by green box) . Data-sheet of VIPER26K says it should.?  (asked ST forum also let see)

Both of those questions would be best answered by your ST account rep!

 

 

 

(Possum Lodge oath) Quando omni flunkus, moritati.

"I thought growing old would take longer"

 

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ki0bk wrote:
Both of those questions would be best answered by your ST account rep!

 

Indeed they should. And while I encourage learning, your questions on this subject suggest that you don't have - yet - the requisite skill set to be designing anything of this sort.

 

Neil

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"Dare to be naïve." - Buckminster Fuller

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Coincidentally, big Clive has just discussed this one.

 

https://www.youtube.com/watch?v=...

Ross McKenzie ValuSoft Melbourne Australia

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Thanks!

[28:47]

It's a monster.

laugh

plus a chuckle due to 'About' on his channel.

Wasn't aware of the value of such on eBay; in AoE is a recommendation to buy off-line power supplies.

 

https://artofelectronics.net/wp-content/uploads/2016/02/AoE3_chapter9.pdf

[page 85]

9.6.11 The flyback converter

 

"Dare to be naïve." - Buckminster Fuller

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Clive seems to rabbit on about the 'quality' of the power supply. Sure the design and assembly looks sound but the main issue with switched mode psus is the capacitors. Many times I've seen shitty electro causing failure in a year or two of operation. Whereas I've had some power supplies still ticking after 10+ years of 24/7 in harsh environments. If the power supply doesn't have Japanese branded electros, I'm suspicious. You can also gauge by the physical size - A 'good' quality electro might be twice the physical size of a similar rating, but lesser 'quality' cap. 

 

I've also had cases where crappy components have also caused the premature demise of a perfectly good design. Diodes going short, high voltage ceramics in the snubber going open etc.

 

 

 

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1. I have attached schematic and BOM.
2. Each phase have range of 85V-600Vacrms , Neutral is present. 600Vacrms is max considering all the worst case scenarios
3. Freq: 50/60Hz , both
4. Output required: 5V/500mA

 

 

1. Selection of MOV is 750V ax max.  What should be ideal max voltage should be selected? On some places I read 10-25% higher than maximum operating is ok. So 660V or higher should or work.
But all I saw that MOV degrade over time, so better to have atleast 20% higher?

 

2. I opened some another brand supply for this. They also placed a combination of C1& C3(two 1uF in series), across U1 also? Is it necessary?

 

3. I want to select two series across U1 : https://www.digikey.com/en/produ...
Unidirectional will select.  U1 has minimum breakdown voltage of 1050V, so have to protect it in any case.
Issue is it this TVS combination have breakdown start from 666V (two in series). Clamping will be 964V. 

The maximum dc voltage when 600Vacrms is reached, will be 850Vdc across U1.  But TVS will start conducting at 666V.
But if higher conducting voltage TVS is selected then its clamping is very high, which deafeats the purpose to protect the 1050V switcher.

 

4. Any other protection which can be added so that switcher canbe protected?

 

5. Any other suggestions?
 

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Surely you could've put more effort into drawing the schematic? 

Where are your calculations?

 

 

 

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Do you need three 33uf (maybe 10 or 22uf will do?) at 500V---that will be pretty large parts.

Add a spot for a small cap across R22  10 pF or so can improve things if you have any issue (or maybe even if you don't)

 

QUIT using 4-way connections, you invite a disaster...draw two 3-way connections!!!

Scoot the resistor over --why draw zig-zag  Do you hope to make us dizzy?

 

 

 

It never ends....

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Sun. Oct 18, 2020 - 08:24 AM
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Big Clive explained the charge balancing resistors for the reservoir capacitors. At 1M + 1M,  I don't think you've taken that on board.

 

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Vindhyachal Takniki wrote:
But all I saw that MOV degrade over time, so better to have atleast 20% higher?
and degrade due to EFT and nearby lightning; might consider GMOV and/or SOV.

An SOV would also suppress for the loads on the AC phases and are typically mounted on the breaker box.

Vindhyachal Takniki wrote:
5. Any other suggestions?
Leaky MOV will cause the 5V to brownout then MOV sizzle then MOV pop; consider fusible resistors to prevent smoke then fire.

 

R21? L2 = 1mH?

Reason : I'm a STM VIPER newbie.

 

MLCC - consider electrolytic for some especially if (when?) we work ourselves back into a MLCC shortage.

 

VIPER's compensator - that may need tuning given load(s) characteristics.

Operating a low frequency network analyzer would aid that though a step load and an oscilloscope may be enough.

 

5. Please be really careful when working with this application and put it into a safety box before connecting it to the mains!.

No as instrumentation will be connected and will be measuring temperatures with an infrared thermometer (what parts to be replacedwink

Do wear eye protection and hearing protection; chance of some flash-over so be careful around breakers and switches (skin thermal protection)

Do follow procedure (power sequence given where one's hands are, both hands!)

Two man rule with a dry run of the WTF procedure.

 

P.S.

Please consider a flyback (safety of customers and operators)

Can acquire bobbins and wind coupled inductors with magnet wire plus Kapton; an off-the-shelf transformer might be a fit given the 5V current is relatively low.

AoE has an inexpensive flyback design though its standby power is likely significantly greater than the STM VIPER and would have to tune it given the much greater off-line voltage.

15V is an advantage as a significant quantity of circuit designs require some voltage.

 


Redesign Overvoltage Protection to Bolster Reliability and Safety | Electronic Design (GMOV)

Bourns - GMOV- Components

Why | Delta Lightning Arrestors (SOV)

https://artofelectronics.net/wp-content/uploads/2016/02/AoE3_chapter9.pdf

[page 86, middle of right column]

...

Alternatively, you will see inexpensive designs in which the transformer itself becomes part of a blocking oscillator, thereby saving a few components.

...

 

"Dare to be naïve." - Buckminster Fuller

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avrcandies wrote:

Do you need three 33uf (maybe 10 or 22uf will do?) at 500V---that will be pretty large parts.

Yes for initial testing I have considered this. Will try to connect 10uF, is it works then will go with this.

 

 

avrcandies wrote:

Add a spot for a small cap across R22  10 pF or so can improve things if you have any issue (or maybe even if you don't)

Thanks understand will do this.

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"

R21? L2 = 1mH?

Reason : I'm a STM VIPER newbie.

"

 

Dont know but reference design had this, so added. I asked earlier ST person why this 20ohm, waiting for his reply.

 

 

 

Anything can be done so that viper can be protected for more than 1050V?  two serie TVS diode will have issue like mentioned in #34?

 

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Vindhyachal Takniki wrote:
Anything can be done so that viper can be protected for more than 1050V?
See your concern as MOV's clamping voltage is at the max; varistors are usually enough.

TMOV25S Series - Thermally Protected from Varistors - Littelfuse

 

"Dare to be naïve." - Buckminster Fuller

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1. @gchapman Have selected TMOV25SP750M for this application.

 

2. Took reference from :  https://www.st.com/resource/en/d...

 

 

3. Have to change L1 & L2 of 1mH values to 1A saturation current around.

But I didnt find L1 with such high voltage standing of operation of circuit with 850Vdc around.

 

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The drawing should not be drawn this way...now I'm gonna contact ST!!

 

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Mon. Oct 19, 2020 - 04:16 PM
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I haven't followed this thread, but Bigclive tested a 3phase PSU recently. You can find him on Youtube.

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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As in ckt in #34,

1. The output required is 5V/500mA i.e 2.5Watt

2. Consider switch losses, buck convert efficiency, what should be the value of R1,R4,R7,R15  in terms of valueand wattage, I should select to be on safe side?

Currently I have selected 33ohms, 4Watt, 5%

 

 

 

 

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Vindhyachal Takniki wrote:
2. Consider switch losses, buck convert efficiency, ...
What is the maximum ambient temperature?

Is this power supply encapsulated, enclosed, or open frame?

Is there airflow beyond convective? (fan or fan-less)

Vindhyachal Takniki wrote:
what should be the value of R1,R4,R7,R15  in terms of valueand wattage, 
I can't quickly answer that because of the wide input voltage range (efficiency is non-linear)

Vindhyachal Takniki wrote:
I should select to be on safe side?
Is there a reliability requirement?

Reason : multiple of the maximum power (two?  four? ...)

 

"Dare to be naïve." - Buckminster Fuller

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1. This is enclosed plastic enclosure, with mostly room temperature only.

2. Fanless

3. There could be all 3 phase avaialble, so output 2.5W load maybe divided into all three phases, or may be cases where only one phase is available, so entire load on single phase, and all current flows from single 33ohms,4W resistor.

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Fix up your schematic first. Put the quality in.

 

You know what your requirements are - you do the calculations. Let the numbers guide your decision.

 

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Currently I have selected 33ohms, 4Watt, 5%

Those should be good up to 2W or maybe 2.5W or even 3 if you can tolerate HOT. ...remember they may be rated to burn up at 4W (zero reserve capacity) 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Wed. Oct 21, 2020 - 10:15 PM