Oshpark Projects

Are you planning on using a regular nanjg protection diode on this? If not then yes just jumper R3 but you could use a regular diode over R3 for polarity protection if you wanted.

Oh yeah, thanks Cereal_killer. I forgot about reverse polarity protection.

Is it okay to run them without the protection diode in a regular 4.2v single cell setup if we dont mind not having polarity protection?

I got the Diodes (BLF17DD part D1) from DigiKey, as in the shipping cart list. I don't see any white or line mark on these at all. The Nanjg ones are labeled S4 with the white mark on the 'S' side, and the DigiKey ones are labeled 41. Any idea how to place these?

Tom the correct values for the voltage ladder are R1-19100 ohm and R2-4700 ohm. The other values are for the gate on the FET and only the 130 is usually needed.

You might have I check the data sheet from the part documentation. It should orient the diode according to the printing somehow.

Ok - I'm asking about the Diode? The 10V 0.57A Diode? The ones I got from DigiKey are unmarked - cant' tell which end is the cathode. I'll try swapping it around I guess. Looks like I'm getting no power thru it to the MCU. Voltage read near nothing.

I don’t see why not. 4.2-4.35v is perfectly safe for the ATtiny13A, so you don’t need the 0.25v voltage drop from the diode. It seems that the only thing it’s protecting is the MCU. If you have physical reverse voltage protection then you don’t even have to think about it.

Check them with the diode test (beep) mode on your DMM. They only work one way, so it’s easy to figure out by comparing the two diodes. I’d also assume that the the text is rightside up on both diodes when they are facing the same direction, but I could be wrong about that! As I said, easy to find out using the DMM.

I thought you said that they were marked 41? Yeah, good call RBD: the datasheet lays the facts out.

Edited, figured out how to do it without piggy backing, this is the bottom of a BLF15DD V3 I’ve modded to work in a piston drive Nitecore D10, the ground ring has the traces to it cut so it can be the contact for the piston, a wire runs threw the drill hole from that ring to MCU pin 3, the top ground ring is still ground as is the 3 sections with via’s on the bottom.

Ohh, missed the datasheet link on DigiKey. Been looking around at generic sources. No idea how to do a "diode test" on a DMM. Looks like my best guess on the cathode following the lettering was wrong - I have to flip it around. This is my last effort to get this board working - resistors I measured on the board were dead on - the diode was the only thing left I could try.

Anode left and cathode right of the lettering. I had to look it up myself just yesterday. But my memory, you know…the 1 went towards the ground ring, the 4 towards the battery positive. That’s what I remember. Anode, cathode, geode, whatever.

Cathode is the “line side” so print right side up, cathode(line) is on the right. The only + trace for the tiny 10 goes from the through via to D1 to Vcc. The via is a direct path from B+ To led+.

Those diodes are marked silly. The only way I can remember it is that the "1" in "41" is on the side where the line usually goes ;)

Ok - the replanted diode from a Nanjg was the culprit. Replaced it (properly) and low voltage monitoring is working. I must have had the "41" in backwards... Ooops! I think it is consistent with the text (cathode to the right).

Wondering - used a Samsung 15M cell to test low voltage. It first triggered at about 3.0v, but if you measure the cell when not under load, it's about 3.2v. So under load, the voltage is lower... Is it fair to use the under load voltage then, or should the voltage level with the LED off be used? Of course it's impossible to test with the LED off, but maybe a fudge factor should be subtracted to account for the loaded drop?

Always measure cell voltage under load. I would elaborate on this but I can't quite think of a good example.

Actually I think Tom E is on the right track, at least in terms of cell damage. My understanding is that resting voltage is where you determine whether the cell is at risk of damage or not. That said, at 3.2v you may as well call it 2.5v. The cell is empty. So in terms of monitoring, the point is somewhat academic.

OK…Mattaus was kind enough to give me his brd and sch of the 7135, I have tweaked them to now be compatible with the IRLML2052, pads and all (so no need to cut the 7135 traces

Here is the Tiny10DD
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Files
https://www.dropbox.com/sh/3zvo72x35ee0f7m/AADnLg-l5TtBHOsIz1y8jnlga

OSHPark permalink
https://oshpark.com/shared_projects/0JRNMWAV

Tiny12DD
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Files
https://www.dropbox.com/sh/wiv2o4g7x0lclsr/AABKsKd58k6Dszc6gZOP4obfa

OSHPark Permalink
https://oshpark.com/shared_projects/SCu1AzNb

These are Alpha release, untested, I have had Mattaus go over it to make sure I didn’t mess somthing up…I have gone over it about 10 times making sure I got the G/S/D pins right

Only change from 10DD to 12DD was a larger ground ring, and I moved the resistors ever so slightly on 12 to loosen things up a bit (since there was more room to play with

No idea how often it’s necessary because when I tested the irlm 2502 on a DD board the gate resistor was needed for consistent operation yet when Dbcstm used it in his neck Ti Texas Poker it was not. Any chance you could move the FET up and over a bit to allow enough room to cut the gate trace from the via and jumper it with a 100-130 ohm R if needed?

Your talking about what is R3 on a 17DD here? What were the reasons you say you needed it when using this baby FET? I’m running a Tiny10 with one of those FET’s and it’s got some quirks, it works but I’m wondering of this could be the answer.