Peter HELP please...Grey kits

Peter I have a couple of your kits and do not know which way the diode and led go
A little help please???

I'm sure someone will work it out and post here. I ordered some too and have no clue what I'm going to do.

I don't even know where to get the diodes yet.

-YC

cman light

The positive terminal of the LED (the one with the bigger metal tab on the side) goes closest towards the IC and connects to pin 2. The band on the diode should point towards the sense resistor.

yclo,

The diode can be had from several sources. Make sure you get a Schottky rated at 1A. Diodes.com is the part referenced in other posts (i think it is B130LAW. Peter correct me if I am wrong here. I have used the On Semiconductor MBR130 in a SOD-123 in other mods and they work as well.

Anyone please correct me if I'm wrong.

CM

I got all my kits working fine, I used a different diode that was a little larger, but works fine. Thanks for the help...

cman light,

Would you let us know which diode you used?

Thanks

I used cental semi conductors diode
http://www.centralsemi.com/pdf/cmsh1-20m_40m_60m_100m.pdf
It's a little larger than the original, but everthing works great, fits nicely etc.

So what is going to happen when I go in and solder on the first diode I find? Will it work, blow up? If I just buy a diode with a matching voltage drop (how how much?) will it work?

Spud

Tater,

If you put a diode in backwards, you could blow up the switching regulator as it will sense no current across the sense resistor. If you don't use a Shottky with low voltage drop, you'll lose efficiency. If you use an under-rated diode, long term it may not survive and you'll burn out the switcher. Best to use a 1A Schottky rectifier. Look for one in a SOD-123 package for a perfect fit on the ckt board pads.

Schottky's typically have a Vf of 0.3-0.4V while your plain ole 1N4xxx germanium have 0.7-0.8V.

Just got my grey kits, now for the important question, how do I pump up the power? I want to drive it at about 500 ma, can i just switch out the sense resistor to a lower value? And I think somebody had posted this question before, but what if I just short the pads where the diode goes? Assuming I don't put the battery in backwards, wouldn't I gain a little bit of efficiency? I can't seem to find the other post with this question.

So in other words, if I use a normal resistor, and put it in right, it will work but not as efficiently? Oh well, I am sure I'll get over it until SOMEBODY has the right ones! Which is the correct way? And if it is the wrong way is it only when the battery is backwards that it will fry? I'll get a 1 amp part, but it won't be schottky unless the diode group buy goes through. It'll temporarily be something else.

Spud

You mean diode, Tater?

As long as you put it in right, you should be fine.

Essentially, Vf of the diode times the current you pass through it will all be wasted as heat. It won't be a HUGE difference, but it will be a difference.

Don't short out the diode pad. The circuit will NOT work without the diode. If you short the diode AND remove the cap, it *may* work, although the current regulation might not work too well. The diode prevents the cap from being discharged when the switching transistor is on.

You can tell the orientation of the diod by the little green line on the pc board that is next to one of the solder pads and is not conected to anything. That is the cathode and you need to match it up with the side of the diode that has a line or marking on it. The cathode side is the side twards the sense resistor(R15).

I couldn't wait for the correct one to appear, so I scoured the town for anything close.
Ended up with a 1 amp Schottky rectifier, but not a surface mount. Guess what....IT WORKS!


There is plenty of room in there.
Thanks for all the info/tips!

In the photo above:
That unused set of pads next to the sense resistor: are they electrically common with the sense resistor, i.e., can they be used to add another resistor in parallel with the sense resistor?

Just double checked with a DMM. Yes.