The SimpleDrive2 - Very easy to set! Now with a feeler!

[rhd]

Re: The SimpleDrive2 - New budget driver.

If I may make yet another suggestion:

Instead of troubling yourself (potentially, if you commercialize) with presetting a million different drivers, why not INCLUDE with each driver, 5 resistors:
0.1, 0.25, 0.5, 1, 2

Then on the PCB, you just need 3 pads for the end user to solder resistors to (either 1, 2 or 3 of them) in series. With combinations of the above, users can hit virtually ANY range they might want. These are just a few of the noteworthy ones (mA):
1666, 1470, 1250, 1136, 1000, 925, 714, 625, 500, 416, 357

Your cost would be 5 resistors, you'd save yourself the hassle of custom orders, complication, etc. Resistors are relatively cheap. Toss 5 in, have the other components on the board already, and they driver is good to go.

 

[Johnyz]

Re: The SimpleDrive2 - New budget driver.

If you're using appropriate wattage resistors, do they really need heatsinking?

I would be more inclined to heatsink the IC. If someone drives a RED or IR from two cells, your LM1117 is potentially dissipating 3-4 volts as heat. That's going to produce 2 to 3 times more heat than the current setting resistor (at least by my math, but I could be wrong)

Probably small optional heatsinks for both. The resistor for 445 is being overdriven a bit now. Let's see if it can be replaced... :thinking:

 

[rhd]

Re: The SimpleDrive2 - New budget driver.

I've got another suggestion -
If you arranged three resistors like so, valued at 1 ohm, 2 ohm, 3 ohm, the layout would allow combinations of parallel and serial solder bridges that could be added by the user to achieve to following currents:

1875
1667
1250
1042
625
568
455
417
341
313
250
208

 

[Johnyz]

Re: The SimpleDrive2 - New budget driver.

rhd: More like 2, 3 and 4 ohm. Not only because 1875 mA is a bit too high for all the IC's I have, but I would have to use PTH resistors so they won't melt. :evil: I would just be making a linear FlexMod...

This indeed calls for more models. The Easy with basic resistor settings, and the Pro with a parallel design, similar to what you said.

I have a version that would even fit in an Aixiz module, but the pads for GND and VCC are only on one side, not thru hole. What do you think, does it matter much?

Also, you may wanna check out the first post, if you hadn't already, I updated it.

 

[Wolfman29]

Re: The SimpleDrive2 - New budget driver.

Hmm... I want to make this as easy as possible for everyone though. I consider myself a pretty good solderer, considering my tools, but not everyone can do SMD chips on through-hole stuffs.

Giving them a supply of resistors would make things more difficult for them because they would have to solder the chips onto it. Now, if I used RHD's design, which I like, by the way, that makes it easier....

But, I am looking for a combination for only the most common diodes for the newbies like I was a month ago.

I am thinking currents of 110mA, 380mA, 500mA, 800mA, and 1.2A.... I will do the math later. But I may use your design, RHD. Thanks!

 

[rhd]

Re: The SimpleDrive2 - New budget driver.

With 2, 3, 4 Ohms - your combinations could produce (I don't think I missed any combinations):

0.92 Ohms 1354 mA
1.20 Ohms 1042 mA
1.71 Ohms 729 mA
2.00 Ohms 625 mA
3.00 Ohms 417 mA
3.71 Ohms 337 mA
4.00 Ohms 313 mA
4.33 Ohms 288 mA
5.00 Ohms 250 mA
5.20 Ohms 240 mA
6.00 Ohms 208 mA
7.00 Ohms 179 mA
9.00 Ohms 139 mA

 

[Johnyz]

Re: The SimpleDrive2 - New budget driver.

Hmm, making a driver specially for 445 that lets me select 1A/1,5A/2A... Food for throught. Also, these buck-boost ICs are pretty expensive... hmm...

 

[rhd]

Re: The SimpleDrive2 - New budget driver.

None of these ICs we've been chatting about are boost - unfortunately.

 

[Wolfman29]

Merged consecutive posts

Surprisingly, boost drivers aren't even necessary... just use two RCR123s.

Secondly... I need an eleven ohm resistance >.>

Brilliant! Just came up with the perfect resistor combination with three resistors.

8Ohm, 2.5Ohm, and 1Ohm

8+2.5+1 = 11.5 Ohm = 108mA <- safe for PHR, very long life
8+2.5 = 10/5 Ohm = 119mA <- near max for PHR but still stable
8+1 = 9 Ohm = 139mA <- not sure yet...
1+2.5 = 3.5 Ohm = 357mA <- safe for LOC
2.5 Ohm = 500mA <-- safe for the new 12x blue rays, yeah?
1 Ohm = 1.25A <-- safe for 445nm

I think that's a good setup, no?

 

[Jufran88]

Re: The SimpleDrive2 - New budget driver.

I'm really interested in seeing the outcome of this project. I was planning something similar with an LMS1585A/87 :beer:

 

[rhd]

Re: The SimpleDrive2 - New budget driver.

How about 2,3,5 ? Considering both parallel and series, you could achieve:

0.97 Ohms 1292 mA (445)
1.20 Ohms 1042 mA (445)
1.88 Ohms 667 mA (12x 405, LPC826 Reds)
2.00 Ohms 625 mA (12x 405, LPC826 Reds)
3.00 Ohms 417 mA (LOC)
3.88 Ohms 323 mA (6x 405?, LOC)
5.00 Ohms 250 mA (Everything below, Reds, 405s, IRs)
4.43 Ohms 282 mA
5.00 Ohms 250 mA
6.20 Ohms 202 mA
7.00 Ohms 179 mA
8.00 Ohms 156 mA
10.00 Ohms 125 mA

 

[Wolfman29]

Re: The SimpleDrive2 - New budget driver.

I don't really want to make it too complex of a soldering job for solderers, so keeping it all in series is easiest (just add the resistor and then bridge the rest of the pads).

 

[Jufran88]

Re: The SimpleDrive2 - New budget driver.

What's the difference in the pot in the flex drive that can go up to 1.5A and using a similar pot for this driver? Is it due to different circuitry used? :thinking:

 

[jib77]

Re: The SimpleDrive2 - New budget driver.

What's the difference in the pot in the flex drive that can go up to 1.5A and using a similar pot for this driver? Is it due to different circuitry used? :thinking:

The Vref for the feedback loop on that particular buck-boost chip is only 0.5V. So at its max of 1.5A the set resistor only needs to dissipate 0.75W. Now in his circuit the pot is not directly on the high current path, it is effecting the output in a different and proprietary way.

 

[HIMNL9]

Re: The SimpleDrive2 - New budget driver.

Brilliant! Just came up with the perfect resistor combination with three resistors.

8Ohm, 2.5Ohm, and 1Ohm

8+2.5+1 = 11.5 Ohm = 108mA <- safe for PHR, very long life
8+2.5 = 10/5 Ohm = 119mA <- near max for PHR but still stable
8+1 = 9 Ohm = 139mA <- not sure yet...
1+2.5 = 3.5 Ohm = 357mA <- safe for LOC
2.5 Ohm = 500mA <-- safe for the new 12x blue rays, yeah?
1 Ohm = 1.25A <-- safe for 445nm

I think that's a good setup, no?

Remember the powers too ..... 1.25A*1.25V=1.56W ..... on an SMD resistor ..... (*POOF*)

 

[rhd]

Re: The SimpleDrive2 - New budget driver.

I've never used an SMD resistor before, but it seems like you should be able to just stack them, and achieve double wattage (half resistance) by using them in parallel. No?