OldFart

In the distant past I have used 780x & lm317t voltage regulators as

variable current regulators, but always with less than 1 amp maximums.

But that was LONG ago, so I can no longer remember the theory behind them.

I now need an lm317t (by preference) design to control the CURRENT

from a 12v switch-mode supply at up to 10-15 amps, and it NEEDS

to be variable across as large a range as possible.

(by the way, the switch-mode psu has its own overload protection)

So, to my mind, I need to have a 'booster' transistor like a mj2955 or

mj3055 'TO3' case power transistor.

But I cant find any current regulator designs with a booster transistor.

I only care about the output current regulation, not voltage,

as can be deduced from the below usage...

This is all in order to construct a VERY custom hot-wire cutter.

It will normally be using quite short and stiff wires, but at very high amps.

So, IF you know of simple designs for a variable-ratio PWM circuit that

can handle 12v @ ~15A then I am interested in those too...

Basically, I am looking for SIMILAR designs to give me inspiration,

or get me thinking in the right direction, but of course a finalised design

would certainly be a bonus...

So if someone can please supply links to appropriate websites

or forums, it would be greatly appreciated.

Thanks in advance...

I'm just starting to play with laser modules, and I wish

for further understanding of these three pin laser diodes

I have in my hand. I have no model numbers or maker names.

But I do have limited specs.

Based on the spec sheet, I have been able to light them safely using a

simple constant-current regulator across two of the pins.

BUT, in the specs, the 'other' pin connects to 'another' diode inside the

case. I am after a laymans-terms description of what this 'other' diode

does.

Also any web-links to non-whitepaper articles would be appreciated.

Thanks guys and gals.

I just had an accident in the workshop, and my entire collection of a few hundred LED-type devices ended up scattered across the floor.

I have been able to sort out most of them visually, but Im stuck with my IR-device collection.

Now I am left with 30 or so IR devices that I cannot identify 'visually' because they all look 'basically' the same.

They are a mixture of IRLEDs, IR Photo-Diodes, and 2pin IR Photo-Transistors.

Can anyone point me in the direction of how I can identify which ones are which of these three types, with as close to 100% accuracy as possible.

I can test by multimeter, CRO, of breadboard circuits, or any combination of them.

Thank you in advance...

I have just inherited a dead Samsung Syncmaster 2493HM TV/Monitor.

Manufactured in 2008 so it is VERY out of warranty, and I wish to fix it myself.

It was DEAD on arrival, but Ive finally resurrected it by (eventually)

replacing one faulty (swollen) capacitor in the PSU.

Im out of electronics faultfinding practice, and have no wiring diagram,

so it took longer than it should have to find...

It now appears to work 'fine' but the OSD menu appears to be invisible.

I can 'blindly' access the OSD menu and adjust the screen brightness

so the menu is actually working in the background, it is just invisible.

Additional information:

1> It is saving any changes I make, as I see the blue led flash, and

it remembers the brightness after I power it down and restart it.

2> All the "current source" OSD , the "wide or normal width" OSD

the "Check cable" OSD, and the "Auto Adjust Locked" OSD messages

ARE appearing OK and easily readable.

3> I believe there should be a 'best resolution' splash-screen at

power-on, according to the manual, but its never seen. (Invisible too?)

4> I have checked DVI, HDMI, and VGA inputs on multiple computers

and its behaviour is the same across all of them.

Any suggestions on tracking this fault anyone? Links to further info is acceptable.

I would also like to find a web-page that gives an 'exploded diagram' of

the OSD menu options, so I can blindly do a "Reset to factory setting".

OR, if someone has come across this issue before, I would love to

hear how you fixed it... assuming you actually did.