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 by VStar650CL ¦  Thu Feb 12, 2009 6:21 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Brushless DC motors - I need some experts ¦  Replies: 19 ¦  Views: 3935

You're quite welcome. It works even better and faster if you port the code up to an 18F, which isn't too difficult. Or you can port down from the '690 to the '616 (that's already in the code) and go really small. Happy if it helps, enjoy. :D

 by VStar650CL ¦  Thu Feb 12, 2009 6:14 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Capacitive Touch Sensor ¦  Replies: 2 ¦  Views: 1638

Leon is right, Microchip has a whole forum section http://forum.microchip.com/tt.aspx?forumid=227 devoted to capacitive touch, plus about a zillion how-to's and app notes and built-in hardware support on some of their micro's.

 by VStar650CL ¦  Thu Feb 12, 2009 5:49 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Brushless DC motors - I need some experts ¦  Replies: 19 ¦  Views: 3935

If anyone wants to try the DIY route, this is a fairly clever PIC16 brushless driver with schem and code... it uses back-EMF for closed-loop control. Not great at low speed (it's sensorless) but a very low part count for what it does. With substituted parts I've driven stuff up to 20A, and you can d...

 by VStar650CL ¦  Wed Feb 11, 2009 11:35 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Need help, A/C matrix ¦  Replies: 17 ¦  Views: 4708

Just a thought, but while the powerline freqency prevents easy charlie-plexing of AC bulbs, there's nothing to prevent you from charlie-plexing the triggers so you won't need 32 outputs. Dimming is often accomplished by "time-slicing" the AC half-wave in between Z-crosses... in other words, a 60Hz h...

 by VStar650CL ¦  Wed Feb 11, 2009 10:50 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Need help, A/C matrix ¦  Replies: 17 ¦  Views: 4708

If you really want to go the AC route, then 25W is pretty much nothing in the triac world. Garden variety BT131's in a TO92 package will more than do the job, DigiKey has them for $0.49US ( http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=568-1770-ND ). The optos will cost you a litt...

 by VStar650CL ¦  Wed Feb 11, 2009 5:56 pm ¦  Forum: New Product Ideas ¦  Topic: Raw Materials for Backlight Kits ¦  Replies: 8 ¦  Views: 2190

New product suggestion... a Tomb of The Unregistered Voter. :wink: :D

 by VStar650CL ¦  Wed Feb 11, 2009 1:13 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Need help, A/C matrix ¦  Replies: 17 ¦  Views: 4708

Bear in mind, that because the cycle length of AC is fixed at 50/60Hz, you can't "charlie-plex" in the traditional sense, especially if you are dimming and not just switching. The power company controls the frequency, not you. Also, triacs are latching devices, just like an SCR... the only differenc...

 by VStar650CL ¦  Wed Feb 11, 2009 12:01 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Need help, A/C matrix ¦  Replies: 17 ¦  Views: 4708

You can control dimming with a triac, just like a wall dimmer. You detect "zero cross" for the AC and then start a dimming timer, then turn the triac on only when the timer expires. In this way, you deprive the bulb of current for part of each AC phase, and voila... dimming.

 by VStar650CL ¦  Wed Feb 11, 2009 11:58 am ¦  Forum: SparkFun Product Questions ¦  Topic: Need help, A/C matrix ¦  Replies: 17 ¦  Views: 4708

He'll still need to use standard triacs triggered by an opto, I don't know of any OT's that will directly handle 25W. He should also use relays (solid state or otherwise) for the short (4-element) leg of the array... hooking up triacs in series is a dangerous business, since N is still present and c...

 by VStar650CL ¦  Wed Feb 11, 2009 9:23 am ¦  Forum: SparkFun Product Questions ¦  Topic: Need help, A/C matrix ¦  Replies: 17 ¦  Views: 4708

What AC voltage, and what wattage on the bulbs? If they're "tree bulbs" and draw less than ~6W, you could control them with 100mA opto-triacs, something like MOC3011's. It would make for a smaller layout than relays and give you the same isolation advantages.

 by VStar650CL ¦  Tue Feb 10, 2009 5:25 pm ¦  Forum: SparkFun Product Questions ¦  Topic: Holder for a stack of button cell batteries? ¦  Replies: 9 ¦  Views: 3704

If you want to go the boost route, try going to the National site and accessing WeBench... you feed it V and A requirements and it will pretty much hand you a design.

 by VStar650CL ¦  Tue Feb 10, 2009 8:34 am ¦  Forum: SparkFun Product Questions ¦  Topic: 16LF88 anyone? ¦  Replies: 6 ¦  Views: 1479

Supply current both awake and asleep is identical for the 'F88 and 'LF88 in the areas where their operating V overlaps (4~5V), so if you're running Vcc>4V there is no advantage at all to using the LF (and the disadvantage that the LF osc only runs to 10MHz).

 by VStar650CL ¦  Mon Feb 09, 2009 2:11 pm ¦  Forum: SparkFun Product Questions ¦  Topic: ADS1256 AINCOM input purpose... ¦  Replies: 8 ¦  Views: 2718

Gotcha, that makes sense. Thanks. :D

 by VStar650CL ¦  Mon Feb 09, 2009 1:03 pm ¦  Forum: SparkFun Product Questions ¦  Topic: ADS1256 AINCOM input purpose... ¦  Replies: 8 ¦  Views: 2718

It can be used as a differential input. Measuring single ended is really a differential measurement referenced to some other voltage. I'll defer to your wisdom, since you're intimate with the part. Page 14 of the datasheet discommends using AINCOM that way, but I'm sure that doesn't mean it can't b...

 by VStar650CL ¦  Mon Feb 09, 2009 11:33 am ¦  Forum: SparkFun Product Questions ¦  Topic: Help with OPAMPS ? ¦  Replies: 5 ¦  Views: 1306

Good advice on all counts. You may not need anything fancy anyhow... an active GSR device is nothing but a specialized ohmmeter, and there are plenty of "build an ohmmeter" app notes out there. It takes no high voltage and a surprisingly small amount of current to pass through human skin. Some years...

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