Search found 237 matches

by kirash4
Sun May 29, 2016 10:23 pm
Forum: Projects
Topic: Powering multiple high power LEDs
Replies: 1
Views: 413

Powering multiple high power LEDs

Hi folks, what's the best way to power a string of high power LEDs? I have 10 3W LEDs that have a Forward Voltage of 3.2-3.8V and Forward Current of 600-700mA. I'd like to solder them together in a parallel string and power them off of one supply. Can I do that with a Femtobuck? Do I need something ...
by kirash4
Thu Jun 26, 2014 9:47 pm
Forum: Projects
Topic: Power Cut-off suggestion needed ...
Replies: 5
Views: 719

Re: Power Cut-off suggestion needed ...

I'll also speculate that perhaps a switched voltage; a "high" working voltage and a "low" programming voltage to the strips, is worth a thought. I assume you have LED strips and so there's no practical way to separate the LED supply voltage from the LPD8806 IC supply voltage. But perhaps at a low e...
by kirash4
Wed Jun 25, 2014 7:06 pm
Forum: Projects
Topic: Power Cut-off suggestion needed ...
Replies: 5
Views: 719

Re: Power Cut-off suggestion needed ...

Good memory. I actually have not tried that yet because I see the same thing happening when I physically turn the unit off then back on. So I figured it's all tied the same thing, whatever it might be. I'm likely wrong here, but at the moment I can't do any testing either because of item (a) above a...
by kirash4
Mon Jun 23, 2014 7:08 pm
Forum: Projects
Topic: Power Cut-off suggestion needed ...
Replies: 5
Views: 719

Power Cut-off suggestion needed ...

I'm working on a design that for the most part is working ... with a few issues. I'm hoping there are some experts here that may be able to suggest some changes to address them. Let's start with the attached schematic. On the left hand side is the charging circuit which uses a MAX8903 to charge a si...
by kirash4
Tue Jun 10, 2014 11:18 pm
Forum: Projects
Topic: LSM9DS0 Serial output issues
Replies: 10
Views: 1001

Re: LSM9DS0 Serial output issues

FYI, using 4.7K pull-ups made no difference. It would still freeze after some random time. It didn't matter if the pull-ups were between the sensor and the buffer, or between the buffer and the Arduino. It resulted in the same random freezes. Looks like I'm stuck running this in SPI mode.
by kirash4
Sun Jun 08, 2014 12:17 pm
Forum: Projects
Topic: LSM9DS0 Serial output issues
Replies: 10
Views: 1001

Re: LSM9DS0 Serial output issues

No, can't do parallel, there's no place to solder on the board (maybe if I stack one on top of the other and reheat it again.) For now I'm going to keep using it as an SPI device. If it proves to be problematic with the SD card, which I'm also reading as a high rate, then I'll look into going back t...
by kirash4
Sun Jun 08, 2014 10:42 am
Forum: Projects
Topic: LSM9DS0 Serial output issues
Replies: 10
Views: 1001

Re: LSM9DS0 Serial output issues

I'd have to disable the resistors on the board and add my own. Should be able to cut the traces I think.
by kirash4
Sun Jun 08, 2014 8:11 am
Forum: Projects
Topic: LSM9DS0 Serial output issues
Replies: 10
Views: 1001

Re: LSM9DS0 Serial output issues

What's the value of the pull-up resistors ? Do you know the I2C bus speed used ? You might have slowed down the loop requesting data, but I think you kept the bus speed the same. I wonder if the bus speed might be on the edge of what is possible given the pull-ups. According to the schematic, the p...
by kirash4
Sat Jun 07, 2014 1:57 pm
Forum: Projects
Topic: LSM9DS0 Serial output issues
Replies: 10
Views: 1001

Re: LSM9DS0 Serial output issues

For testing purposes, I'm running the exact code that's on the example page: https://learn.sparkfun.com/tutorials/lsm9ds0-hookup-guide/basic-arduino-example Running the sensor in I2C mode with that exact code, will freeze after some random amount of time; sometimes seconds, sometimes minutes, eventu...
by kirash4
Sat Jun 07, 2014 12:12 am
Forum: Projects
Topic: LSM9DS0 Serial output issues
Replies: 10
Views: 1001

LSM9DS0 Serial output issues

UPDATE: After switching the module to use SPI mode instead, I don't experience the freezing anymore. So perhaps it does indeed have something to do with I2C mode. Even at a 500ms refresh rate, it was still quitting. Not so with SPI. It's been running with 5ms refresh for the past half hour, no hicc...
by kirash4
Sun Jun 01, 2014 1:01 am
Forum: SparkFun Product Questions
Topic: LSM9DS0 IMU Breakout problems
Replies: 16
Views: 4284

Re: LSM9DS0 IMU Breakout problems

FYI folks, I've ditched using one of the level shifting boards that SFE offers, and got a TXS0104 instead. The unit came up and worked flawlessly right of the bat. There is something to be said for using the proper hardware. That's not to say that using SFE's level shifter is wrong, it probably work...
by kirash4
Fri May 30, 2014 12:03 pm
Forum: Projects
Topic: Delayed power-off
Replies: 4
Views: 705

Re: Delayed power-off

One other thing I forgot was to add a flyback diode on the main switch. For voltages no higher than 4.2V, what's a recommended (SMD) part?
by kirash4
Thu May 29, 2014 2:05 pm
Forum: Projects
Topic: Delayed power-off
Replies: 4
Views: 705

Re: Delayed power-off

The main power switch cuts off power between the battery and the boost circuitry (which in turn powers the MCU.) Actually, IT'S slightly more than that. The full path is for the MCU is: battery -> MAX8903 -> power switch -> LM2621 -> MCU It's done that way so that I can apply power to the MAX8903 an...
by kirash4
Thu May 29, 2014 1:09 pm
Forum: Projects
Topic: Delayed power-off
Replies: 4
Views: 705

Re: Delayed power-off

Just thought of something, will a 10K pull-down on the IO pin that's responsible for managing the Sziklai pairs be helpful here? When power is switched off from the entire unit (and the MCU doesn't tell the Sziklai pairs to power down,) will the pull-down take care of that?
by kirash4
Thu May 29, 2014 1:04 pm
Forum: Projects
Topic: Delayed power-off
Replies: 4
Views: 705

Delayed power-off

I have a bit of a unique situation here and hoping someone might have a better idea of what I can do, even if it means going through a hardware redesign. I have LED strips with LPD8806 drivers that are powered directly from a single Li-Ion Power Cell so they can take advantage of the amp burst. They...