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Re: Hooking up two Li-Po batteries in parallel = bad?

 by Duane Degn ¦  Thu Jul 05, 2012 9:46 am ¦  Forum: SparkFun Product Questions ¦  Topic: Hooking up two Li-Po batteries in parallel = bad? ¦  Replies: 4 ¦  Views: 947

If the batteries have the same chemistry, capacity, state of charge, then yes they can be parallelled. SparkFun sells a pack with three LiPo cells in parallel. The parallel pack SparkFun cells does have a PCB, but IIRC the protection circuitry is between the cells and the connector. The batteries th...

Re: Large number of servos twitching in repeating pattern

 by Duane Degn ¦  Wed Jul 04, 2012 5:27 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Large number of servos twitching in repeating pattern ¦  Replies: 21 ¦  Views: 2899

I don't know if you'd consider switching your microcontroller or not, but if you'd be willing to use a Propeller chip, you could drive up to 32 servos at once. Here's my thread about driving 32 servos (includes a video of it in action). http://forums.parallax.com/showthread.php?137597-QuickStart-Dri...

Re: dead speakjet

 by Duane Degn ¦  Sun Jul 01, 2012 12:34 pm ¦  Forum: SparkFun Site Questions/Comments ¦  Topic: dead speakjet ¦  Replies: 4 ¦  Views: 1515

I think I got a dead speakjet. I tried to use the simple demo circuit and got nothing from the chip. The demo schematic shows a 120 ohm speaker and I think they must mean 12 ohm. I didn't have a 12 ohm but tried a 10 and an 8 and neither gave me anything. Did I screw up or is it possible the chips ...

Re: LiPo Battery Charger Question

 by Duane Degn ¦  Sat Jun 02, 2012 4:04 pm ¦  Forum: SparkFun Product Questions ¦  Topic: LiPo Battery Charger Question ¦  Replies: 2 ¦  Views: 483

Your charger probably needs to communicate with a PC before it will draw much power from the USB port. A device has to request power from a PC over USB before drawing more than minimal current. Since your charger isn't able to communicate with a PC it never starts its charge cycle.

Re: Low Cost Vision Module

 by Duane Degn ¦  Fri Jun 01, 2012 11:24 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Low Cost Vision Module ¦  Replies: 70 ¦  Views: 28870

I've been interested in some sort of machine vision solution for microcontrollers for a while. I've collected a few links to Propeller (the CMUcam4 uses a Propeller) machine vision projects I've seen. I tried Hanno's method of using an 8-bit ADC to capture B&W video from a NTSC camera. I even displa...

Re: AA powered LED controller.

 by Duane Degn ¦  Mon May 28, 2012 9:11 pm ¦  Forum: SparkFun Product Questions ¦  Topic: AA powered LED controller. ¦  Replies: 14 ¦  Views: 1108

Make sure a take a look at SparkFun's tutorial.

http://www.sparkfun.com/tutorials/219

See RobertNija's comment and rsp's reply about individual resistors on LEDs.

Re: AA powered LED controller.

 by Duane Degn ¦  Mon May 28, 2012 5:15 pm ¦  Forum: SparkFun Product Questions ¦  Topic: AA powered LED controller. ¦  Replies: 14 ¦  Views: 1108

basically i have arduino pwm pin > 1k resistor > 2n2222 transistor> 47ohm resisor > 6 leds in parallel(single color) Does each LED have it's own resistor? If not, they should. Otherwise more current will go through some LEDs than others and they wont be uniformly bright. An easy way to do this, whi...

Re: Simple USB I/O product?

 by Duane Degn ¦  Mon May 28, 2012 4:47 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Simple USB I/O product? ¦  Replies: 8 ¦  Views: 1212

I recommend SparkFun stuff on the Parallax forums all the time so I think it's only fair I recommend a Parallax product here, especially when it such a good fit for the task. I'm a big fan of Parallax's Propeller. It's really hard going back to a single core AVR chip after having multiple cogs that ...

Re: Using Barcode Scanner USB with a Microcontroller

 by Duane Degn ¦  Thu Jan 26, 2012 12:13 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Using Barcode Scanner USB with a Microcontroller ¦  Replies: 1 ¦  Views: 2309

It looks like member#261580 figured out his problem because the comment has been edited to: Works nicely on a microcontroller! This comment was a reply to my comment: You can use this with a microcontroller. You do need to make a different cable. A Cat5 cable works fine. You also need to configure t...

Using Barcode Scanner USB with a Microcontroller

 by Duane Degn ¦  Thu Jan 26, 2012 8:43 am ¦  Forum: SparkFun Product Questions ¦  Topic: Using Barcode Scanner USB with a Microcontroller ¦  Replies: 1 ¦  Views: 2309

I have some notes on how to use SparkFun's Barcode Scanner USB (SEN-09166)with a microcontroller in the comments section of the product page. I thought it would be easier to answer questions about using the scanner here in the forum instead of within the commnets. Here's a link to the product page: ...