Please explain "Connect LED neg to board rim for Single mode

[kosPap]

well I know it works for some boards Z(like the RV7 similar drivers)Z(dx 7880)

but today I did it for some other too
The 3.6V buck-boost board (DX 15880)
and a KD domain PWM buck driver for P7 (

But I need something to be explained...why does it work and beats the drivers modesZ?

Also taking the liberty to use Netkidz diagram, I made my own just to ask are these setup the same thing?

while it does not appear so, in the second version the neg wire to the led is NOT connnected to the neg driver pad, but at the rim...

 

[uk_caver]

But I need something to be explained...why does it work and beats the drivers modesZ?

It seems that in many multilevel drivers, the variable power is achieved by using a FET in series with the negative LED connection, and turning that FET on and off to give variable power by PWM (different ratios of 'on time' to 'off time' giving different average brightness from the LED).
Connecting the LED '-' to the board rim bypasses the FET, and so means that the board ends up single-level.

However, if a board is regulating the maximum power control by using a current-sense resistor in series with the LED '-' connection, (as many boards may be doing), connecting the LED '-' straight to the board rim also bypasses that resistor, and could end up with excessive power going to the LED.
To try and make sure that isn't happening, the current at maximum power before changing the LED connection could be compared with the current afterwards to make sure they're not different.

Also taking the liberty to use Netkidz diagram, I made my own just to ask are these setup the same thing?

No, they're not the same thing.
In the first circuit, without any connection to the board rim, the driver will not be operating normally. Depending on the circuit, it may be that some current would still flow through it to the LED, but possibly in an unpredictable or unstable manner.

 

[kosPap]

thanks for the input...in the meantime I gave it a go and made a MC-E module cinnecting LED - directly to body.
It works Ok (so i got lucky)

Here is a pic...(it is messy but I will be re-doing it soon)

I got one more question though....Can I connect both the driver neg AND the rim neg in order to avoid opening the pill again if I want ot go multimode?

TNX, kostas

 

[kramer5150]

thanks for the input...in the meantime I gave it a go and made a MC-E module cinnecting LED - directly to body.
It works Ok (so i got lucky)

Here is a pic...(it is messy but I will be re-doing it soon)

I got one more question though....Can I connect both the driver neg AND the rim neg in order to avoid opening the pill again if I want ot go multimode?

TNX, kostas

(DIY-noob alert!)
:thinking:... By bypassing the "-" half of the circuit, aren't you just creating a direct drive circuit?

:thinking:😱:thinking:

 

[uk_caver]

(DIY-noob alert!)
:thinking:... By bypassing the "-" half of the circuit, aren't you just creating a direct drive circuit?

:thinking:😱:thinking:

It depends on the circuit, and where any current sensing is.

I think that current sense resistors usually are on the low side, and so would be bypassed by connecting LED- to ground.

There are some drivers where there isn't a current-sense resistor (particularly the KD +/or DX boost driver that has a constant voltage output), where the only thing that is bypassed by connecting LED- to ground is the PWM FET, but that is a fairly unusual driver.

If variable power control is done by a microcontroller chip driving a FET to give PWM, sitting on top of some kind of current-regulated driver, the best way to make the driver single-mode is to bypass just the FET, (or turn it permanently on), since that leaves the current regulation in operation.

 

[koala]

-----

 

[uk_caver]

It really depends if the driver is doing current regulation, and if so, where it's doing any current sensing.

 

[kosPap]

I had to bring up this topic again cos I need some help on a driver I tried to "single-mod"

Anyway, here is how I wired it. Now this kind of pad extends to the other of the board too AND makes contact with the pill....

So the questions are:
- Can this driver be put into single mod by soldering at the neg rim? ( i cannot recognize the parts)
- Am I direct driving the LED this way?
Actually I am running in some complications by the pressure that is exerted on the driver board (somehow there is some jiggling the way it is installed/soldered)... it draws 3.3A (what is expected in high mode) and at 4.4A when it pressed hard (which happens to be the DD draw with my batts)

thanks for all your efforts exlpaining electronics to me...kostas

 

[kosPap]

and while I wait for answers can someone "read" the shining beam P7 driver componets to tell if it can be wired to single mode?

 

[VidPro]

...

😗one of these things is not like the other 😗
in the first picture, you have no power shown going to the driver, so unless the thing is just a resister, it aint gonna work like that. them lectronics things (usually) need power to run, like a mosfet has to have power from the battery to trigger its gate.

note: there ARE drivers that work like that, Nite-Eyes switch for example, but it is dependant on the voltage existing through the "load" either an led or a incan bulb. so when you connected it with only 2 wires, the voltage potential across it was used to do the switching and stuff. a Rare design.

and the second one doesnt look correct either :-( usually the positive is straight through, you now have the negative ALSO connected straight through (if the positive is straight through), so from the way most of these driver things control, the second pic looks like your just conneted direct still :-(

but i donno, already messed up your other thread.

 

[Justin Case]

and while I wait for answers can someone "read" the shining beam P7 driver componets to tell if it can be wired to single mode?

That Shining Beam driver looks like an 8xAMC7135-based driver. Most likely, the 3 modes are achieved using either an ATMEL (often, these Chinese drivers use the Tiny13V) or a PIC12F629 PWM controller. The cheap answer for wiring for single mode is to configure the Shining Beam board just like a 2-parallel-board, single mode 8xAMC7135 sandwich would be wired (e.g., two DX1886 boards in a parallel sandwich).

 

[Justin Case]

I had to bring up this topic again cos I need some help on a driver I tried to "single-mod"

Anyway, here is how I wired it. Now this kind of pad extends to the other of the board too AND makes contact with the pill....

So the questions are:
- Can this driver be put into single mod by soldering at the neg rim? ( i cannot recognize the parts)
- Am I direct driving the LED this way?
Actually I am running in some complications by the pressure that is exerted on the driver board (somehow there is some jiggling the way it is installed/soldered)... it draws 3.3A (what is expected in high mode) and at 4.4A when it pressed hard (which happens to be the DD draw with my batts)

thanks for all your efforts exlpaining electronics to me...kostas

CPFer old4570 has used many of these boards. Try sending him a PM to see if he can read off the markings for you.

The KD description calls this board a "direct drive" already, without any fancy wiring changes.

The IC with the white dot on it looks like it says ATMEL and might be a 24LC512.

 

[kosPap]

guys thanks again....I am taking some of your time to cover my lack of electronics knowledge...

regarding rewirng the SB driver i guess I will have to see ibto it....(have already saved some threads on the sandwiches the basic ones from Netkidz and the norwegian memmer one included)

Best luck with your projects kostas