2.3V @ 1.3A Case Positive Driver?

[3zuli]

I saw the datasheet of lm1117 and it says it can supply 800mA, but it needs cooling (heatsink)

 

[HIMNL9]

I saw the datasheet of lm1117 and it says it can supply 800mA, but it needs cooling (heatsink)

Yes, this is the reason for use 3 of them (so each one hold 433mA), and for dip them in thermally conductive silicone (so the glue can transfer the heat from the components to the case)


Edit: hell, it's a damn pain you-know-where, to fit all the components in less than 16mm of diameter ..... you said that you have 15mm of deep in the lower portion of the cylinder, mind if it take 12 or 13mm of thickness and is on 2 discs ? ..... not sure, have to see tomorrow, but in this way, maybe i can fit all in the space that then you can dip in the thermal silicone

BTW, i forgot to ask you if you need that it have a side as contact for the battery, or if is wired.

 

[daguin]

Yes, this is the reason for use 3 of them (so each one hold 433mA), and for dip them in thermally conductive silicone (so the glue can transfer the heat from the components to the case)


Edit: hell, it's a damn pain you-know-where, to fit all the components in less than 16mm of diameter ..... you said that you have 15mm of deep in the lower portion of the cylinder, mind if it take 12 or 13mm of thickness and is on 2 discs ? ..... not sure, have to see tomorrow, but in this way, maybe i can fit all in the space that then you can dip in the thermal silicone

BTW, i forgot to ask you if you need that it have a side as contact for the battery, or if is wired.

All of the space in the stepped cylinder is available. I can even ream out the lower portion some to add diameter if needed.

It will be wire connections.

The lower portion can be filled with silicone if needed.

Peace,
dave

 

[Kenom]

I've used the amc7135 in my most recent 2W Kryton build and it worked very well. Was getting 1.7W from 1400ma. I even built my own board for them as I didn't like the setup on the DX driver boards.

Keep in mind I do not have my own etching compound so had to grind the pcb away with a dremel.

The LM337 negative regulator is also a very good idea. Exactly the same thing as a LM317 but made for case positive.

 

[HIMNL9]

Ok, i think i got it ..... played a bit with coreldraw, and found that, if you can end with 25mm of diameter (or also 24) in the low part, i can fit all on a single board, and there's also too much free space (relatively talking ), and overall keep all the 3 regulators on a single side (the bottom side), so you can thermally couple it in two ways, depend if the space is opened or closed.

If the space is closed, like a tailcap, you can just place some thermal silicone in the cap and push the pcb down, til it reach the bottom, having the regulators thermally coupled with the cap, both for contact and from the glue, and the upper place free for solder the wires ..... if the place is opened, like a tube, you need to find a disc of aluminium or similar with the same diameter of the tube (better if it force a bit), and 2 or 3 mm thickness, then make some holes or cut some spaces on the border (if you need to pass some wires to the other side), and use it for close the tube, then glue the driver on it ..... this way, the disc couple the regulators and the case thermally.

it become something like this (the larger circle is 25mm, the second one is 24mm):

The red triangles is where it can be filed away if some wire need to pass, in these places there's no tracks ..... for use it as positive case, you need to connect it between the positive pole of the battery and the case, so probably the better place where to connect it, may be the tailcap (but in this case, how can be carried there the negative pole, for the filtering ?) ..... another possibility can be to incorporate it in the battery holder (if you use the 3 AAA holder) placing it at the top of the plastic holder, but this way there's no thermal coupling with the case .....

EDIT: i forgot to say, there's a reason for use 2 0.56ohm resistors instead one 1ohm, and is cause, with that current, it need to dissipate at least a watt and half, and i just have 1W SMD resistors

Or, but this require some experiments with a dummy load, for the safety of the diode, first, place it "in reverse" ..... i used one time this system, cause was an emergency repair and had no other way for do it, but it's weird ..... mean, it work only as series current limiter, not ofcourse as voltage regulator, also have to take away all the tantalium caps, and connect it in this way:

..... and this is something that, usually, make electronic professional experts and "electronics purists" start to shout "HERESY, HERESY" and hunt you with forks and ropes .....

There is an alternative, if it cannot be connected to the positive pin of the battery, and is to use LM137, that is a negative regulator ..... i designed the circuit in the way that can be used both with the 1117 and the 137, is enough invert the polarity of the tantalium capacitors (and the polarity of the wires, ofcourse ), but i have to say that, first, the 137 have a dropout of at least 2V, so you need a bit more voltage for the input, and they dissipate a bit more power in heat, and second, opposite than for the 1117, that i already used them in parallel with success, i never tried to use the 137 in parallel, til now, so i don't know how they work in these conditions, especially for the long times.

What do you think that is better ?