I Don't Understand

[EasyGoing1]

Re: I Don't Understand

BTW, if you remove one of the two R13 (2R20) resistor, the constant current will drop down in half to 90mA.

So I fixed the lamp ... here's how I did it:

I ordered these CV/CC power supplies and I used these LEDs, and I made two serial strings of those LEDs and connected them in parallel... I got an old printer power supply that kicks out 30 volts but as it turns out all the LEDs needed was 16 volts ... and I set the current to 280ma and its working like a champ.

[EasyGoing1]

Re: I Don't Understand

[QUOTE=budm;861331]Where is the meter connected to? In series with the LED string?[quote]

Yes

Unless that spec sheet diagram does not match what you have, or 5602 is no longer regulating the current.
See the calculation and how the 5602 is connected, verify if it matches your board lay out as far as R13 connection is concerned. I see that one end of the resistor is connected to pin 7, 8 for sure, most Chinese manufacturers will just copy the circuit from the IC manufacturer application circuits.

OK, I'll have a look ... but im thinking if I just use two strings of LEDs connected in parallel it should be fine, unless it isn't bright enough but with 8 or 10 total of these LEDs I think it might be alright.

[budm]

Re: I Don't Understand

Where is the meter connected to? In series with the LED string? Unless that spec sheet diagram does not match what you have, or 5602 is no longer regulating the current.
See the calculation and how the 5602 is connected, verify if it matches your board lay out as far as R13 connection is concerned. I see that one end of the resistor is connected to pin 7, 8 for sure, most Chinese manufacturers will just copy the circuit from the IC manufacturer application circuits.

[EasyGoing1]

Re: I Don't Understand

BTW, if you remove one of the two R13 (2R20) resistor, the constant current will drop down in half to 90mA.

NOPE!

[budm]

Re: I Don't Understand

BTW, if you remove one of the two R13 (2R20) resistor, the constant current will drop down in half to 90mA.

[budm]

Re: I Don't Understand

Unless I can somehow modify this circuit so that it puts out 120ma instead of more than double that amount which it does now ... I wont be using it at all ... unless I break that series up into two sets and run them in parallel...

Read post 34, I already show you how that 180mA comes about, so to change the LED current setting you just need to change the value of the resistor. It is all in the spec sheet.

[sam_sam_sam]

Re: I Don't Understand

I'm about as stubborn as they get ... I WILL get this working one way or another ... know that!

I have the same problem

M I prefer using the method that is as stable and long term as possible, and the solution that people agree with - who know more than I do ... but if that avenue fails,

Yes I prefer to do it this way also

I've got wire cutters and a pretty decent soldering iron ... bunch of caps and resistors and diodes laying around ... ill spit and duct tape something together eventually ... but for the time being, I sit among the great weevils on the mountain and digest as much knowledge as I can before they get sick of me ... ill let you know what the final solution is when I get there. :-)

But if all else fails resort to something like this

[EasyGoing1]

Re: I Don't Understand

I have been watching this post to see if you have figured some way to make it work

I'm about as stubborn as they get ... I WILL get this working one way or another ... know that! I prefer using the method that is as stable and long term as possible, and the solution that people agree with - who know more than I do ... but if that avenue fails, I've got wire cutters and a pretty decent soldering iron ... bunch of caps and resistors and diodes laying around ... ill spit and duct tape something together eventually ... but for the time being, I sit among the great weevils on the mountain and digest as much knowledge as I can before they get sick of me ... ill let you know what the final solution is when I get there. :-)

[sam_sam_sam]

Re: I Don't Understand

Unless I can somehow modify this circuit so that it puts out 120ma instead of more than double that amount which it does now ... I wont be using it at all ... unless I break that series up into two sets and run them in parallel...

I have been watching this post to see if you have figured some way to make it work

I have some LED power supply module that are the same exact way that you have to match the current level but when you try to do this the voltage goes up

What I found out is that the LEDs that I was trying to use did not match current draw that the LEDs that were in the LED module light

I have not yet figured out how to overcome this problem yet

Right now now I do not have time to figure this out

Maybe the week of Thanksgiving when I am off from work I will have some time to figure this out and some other project problems at this time

[EasyGoing1]

Re: I Don't Understand

I would run constant current of 120mA (80% of the max spec.).
The VF of the LED will vary withe current flwoing through the LED, temperature all affect Vf, that is why you should use constant current source, 30V may be OK it depends on the Vdrops of the Constant current active control element at the needed current and variation of the total Vf of the LED string, you want it to have head room for the Output Voltage to go up and down as needed to maintain constant current.
See page 12 of the graph which is typical spec provided by the LED manufacturer which I doubt if you have it for your LED. If you have constant current power supply then you do the measurement and see what you get with your LEDs you will be using.

https://cdn.badcaps-static.com/pdfs/...7f6e02e49a.pdf

Good caps: I.E. Panasonic FM/FC/FR series, and many other Japanese manufacturer.

Unless I can somehow modify this circuit so that it puts out 120ma instead of more than double that amount which it does now ... I wont be using it at all ... unless I break that series up into two sets and run them in parallel...

[budm]

Re: I Don't Understand

I would run constant current of 120mA (80% of the max spec.).
The VF of the LED will vary withe current flwoing through the LED, temperature all affect Vf, that is why you should use constant current source, 30V may be OK it depends on the Vdrops of the Constant current active control element at the needed current and variation of the total Vf of the LED string, you want it to have head room for the Output Voltage to go up and down as needed to maintain constant current.
See page 12 of the graph which is typical spec provided by the LED manufacturer which I doubt if you have it for your LED. If you have constant current power supply then you do the measurement and see what you get with your LEDs you will be using.

https://cdn.badcaps-static.com/pdfs/...7f6e02e49a.pdf

Good caps: I.E. Panasonic FM/FC/FR series, and many other Japanese manufacturer.

[EasyGoing1]

Re: I Don't Understand

First question will be what is the load?

I was thinking 9 LEDs in series ... rated at 3v / 150ma so I'm thinking the power supply should be able to supply roughly 30 volts at 150ma?

So what are you going to do with that power supply? It is a good CC power supply that should be re-capped with good caps.

What's your definition of "good caps"? and where would I get them?

[budm]

Re: I Don't Understand

It cannot force 180mA through 400 Ohms resistor if the power supply cannot go up high enough to force 180mA through the resistor, the Voltage across the load is varied to maintain constant current.
"How do I take 120V AC and kick out some decent DC voltage at roughly 100 to 120 milliamps in the small space I have to work in? Remember STJ recommended the capacitive dropper ... what are your thoughts on that option?"
First question will be what is the load? 1 LED? 10 LEDs, 100 LED's? You need to know what the load requirement is first, you already know what the required current but now you need to know the load requirement is so you can make power supply that puts out enough Voltage to force 120mA through the load.
So what are you going to do with that power supply? It is a good CC power supply that should be re-capped with good caps.

[EasyGoing1]

Re: I Don't Understand

So when you put 400 Ohms in series, there is no way the circuit can force 180mA through 400 Ohms resistor + the LED's, the power supply does not have enough Voltage to force 180mA through, 400 Ohms x 0.18A = 72V so no way it will happen.

When I dropped the series resistor down low enough to make it stop blinking, it still drew 170ma ... and when I had the 400 in there, it drew 170ma ... just not constantly (obviously) ... its as if a series resistor didn't do Diddley squat for limiting current ... which kind of makes sense if the power supply is a CC at 180ma .... what respectable CC power supply would give two craps about a pesky series resistor ... just another obstacle to overcome for the power supply is all ... it's gonna deliver 180ma come hell or high water ... or pulse on and off like a whiney two year old if the load is too heavy ... but at least it's putting forth a valiant effort...

So all of this analysis of the circuit was fun and all ... but the question is still on the table: How do I take 120V AC and kick out some decent DC voltage at roughly 100 to 120 milliamps in the small space I have to work in? Remember STJ recommended the capacitive dropper ... what are your thoughts on that option?

OR, are you thinking we could modify the existing power source to put out less current so my LEDs don't go belly up? .... THAT actually sounds like FUN!

[EasyGoing1]

Re: I Don't Understand

https://www.badcaps.net/forum/attach...8&d=1541545003
Looks like line filter, rated at 3A 12VAC.

Ended up being the on off switch ... I'll take a BIG FAT ZERO for that one ...

[EasyGoing1]

Re: I Don't Understand

looks like a connector block ..
p.s there seems to be a stray bare wire melted into the wire nut .

Actually, it ended up being the on off switch...

[budm]

Re: I Don't Understand

U1 BP2326:
https://cdn.badcaps-static.com/pdfs/...aa1495d297.pdf

U2 BP5602: http://bpsemi.com.cn/uploads/file/20...170036_863.ppt


Looking at the board layout, it looks like U1 (BP2326) is set up as the Buck converter to supply the Voltage to run the U2 (BP5602) LED driver.
Resistors (R13/R13 1 (2R20 Ohms in parallel = 1.1 Ohms) connected in parallel) at CS pins 7 & 8 of BP5602 determine the LED current setting.
Formula: Rcs = 0.2V/Iout, that means it is set for about 180mA (Iout = 0.2V/1.1 Ohms) of constant current which is what you have found out in the earlier test. So when you put 400 Ohms in series, there is no way the circuit can force 180mA through 400 Ohms resistor + the LED's, the power supply does not have enough Voltage to force 180mA through, 400 Ohms x 0.18A = 72V so no way it will happen.

[budm]

Re: I Don't Understand

https://www.badcaps.net/forum/attach...8&d=1541545003
Looks like line filter, rated at 3A 12VAC.

[budm]

Re: I Don't Understand

You will plug the device to be tested into the Isolation transformer (L and N are floated).

[petehall347]

Re: I Don't Understand

unless i am thinking wrong the isolation transformer goes before the scope . or is the DUT ?