Search found 35 matches

by anhingus
Fri Nov 12, 2010 1:04 pm
Forum: SparkFun Product Questions
Topic: Homebrew LED growlight
Replies: 11
Views: 2276

Re: Homebrew LED growlight

anhingus suggests that ohm's law is linear, diodes ain't.

last he heard, the 'd' in led stood for diode, but that was some time ago.

LM7805 - check the national data sheet - can be used as a constant current source

prudent, methinks, to breadboard stuff before commenting.
by anhingus
Wed Nov 10, 2010 7:37 am
Forum: SparkFun Product Questions
Topic: Homebrew LED growlight
Replies: 11
Views: 2276

Re: Homebrew LED growlight

hello, rich - at the moment i have 72 leds in parallel on a board, 5-volt wallwart, one resistor as current limit. works well. looking at specs on your royal blues, try using a 12-volt wallwart, an LM7805 voltage regulator, and a 5-watt multiturn wirewound pot for your resistor. making assumption yo...
by anhingus
Tue Nov 02, 2010 1:15 am
Forum: SparkFun Product Questions
Topic: Punch card reader
Replies: 6
Views: 792

Re: Punch card reader

you might be interested in looking up herman hollerith on the web, the grand-daddy of electric card reading, and see how he did it.
by anhingus
Fri Oct 22, 2010 5:33 pm
Forum: SparkFun Product Questions
Topic: Looking for RGB LED in flat package...
Replies: 3
Views: 402

Re: Looking for RGB LED in flat package...

futurelec has an 8x8 rgb matrix for around $10
by anhingus
Wed Oct 20, 2010 5:37 pm
Forum: SparkFun Product Questions
Topic: Using Photocells to Track Position of a Light Source
Replies: 1
Views: 344

Re: Using Photocells to Track Position of a Light Source

you could do ballpark stuff using photocells but it would take quite a few of them. say 2 sets of 18 arranged every 10 degrees on a semicircle perimeter. very crude pointing at best. a photocell can't tell left from right or top to bottom for positioning purposes which is why mounted servo rotation ...
by anhingus
Fri Oct 15, 2010 6:56 am
Forum: SparkFun Product Questions
Topic: Music Sensor
Replies: 3
Views: 405

Re: Music Sensor

coding?

if you use a pressure mat for each stair tread you have individual switches to turn a chip on and off.

why use a microprocessor?
by anhingus
Mon Oct 04, 2010 5:39 pm
Forum: SparkFun Product Questions
Topic: Help with the Picaxe 8 Pin Motor Driver Board *SOLVED*
Replies: 4
Views: 583

Re: Help with the Picaxe 8 Pin Motor Driver Board

i have the L293D chip but not the board you are using. the enable pin of the chip needs to be hi [5v] for the chip outputs to work. pin 1 hi allows pins 3,6 to output pin 9 hi allows pins 11,14 to output. check the voltage level on whatever enable pin you need to use. if that's good, substitute your...
by anhingus
Sat Oct 02, 2010 7:16 pm
Forum: SparkFun Product Questions
Topic: electronically controlled ball valves
Replies: 2
Views: 579

Re: electronically controlled ball valves

part ii - getting senile, i'm afraid for auto on, you can use a mercury float switch which is normally open when floating, closes when no longer floating. the open-close levels are determined by a plastic rope tied mid-level to the inside of the container or wherever. this is basically what they do ...
by anhingus
Sat Oct 02, 2010 7:07 pm
Forum: SparkFun Product Questions
Topic: electronically controlled ball valves
Replies: 2
Views: 579

Re: electronically controlled ball valves

go to rainbird or other irrigation supply sites for reasonable prices along these lines. you could - if you a more hands-on project - pick up an automotive windshield wiper motor, attach to a brass ball valve handle, use limit switches to kill power at full-open, full-close, and rig a double-pole, d...
by anhingus
Sat Oct 02, 2010 6:26 pm
Forum: SparkFun Product Questions
Topic: Hardware design
Replies: 1
Views: 320

Re: Hardware design

trying to start a flame war, eh? however, if i wanted a good basic book in this ballpark i would only buy forrest mims 'getting started in electronics, a complete electronics course'. if you want usb instrumentation, then sparkfun is a good place to start. you will want a microcontroller with at lea...
by anhingus
Sat Oct 02, 2010 10:56 am
Forum: SparkFun Product Questions
Topic: Sunrise alarm clock
Replies: 13
Views: 1403

Re: Sunrise alarm clock

actually not much of a shortcoming at all. the microcontroller - from one point of view - is pretty much an interface device using software to replicate hardware function at a discrete level. your project is eminently doable with an mcu [cheap, as in picaxe] and there is lotsa stuff on the web for u...
by anhingus
Sat Oct 02, 2010 10:46 am
Forum: SparkFun Product Questions
Topic: Circuit to activate and fade a LED by motion
Replies: 3
Views: 577

Re: Circuit to activate and fade a LED by motion

you could do an invert of this idea.

put a photocell in series with a powered led and use the voltage change on a hand pass as an input.

that is, let the led do its own dimming and pick off the signal.

if you want a last-forever battery, try an LM3909 with this project.
by anhingus
Fri Oct 01, 2010 12:41 pm
Forum: SparkFun Product Questions
Topic: Sunrise alarm clock
Replies: 13
Views: 1403

Re: Sunrise alarm clock

programmer? use a digital pot to control a string of flashlight bulbs with an LM317 voltage regulator with either voltage or current config. bulbs are a dime, regulator a quarter. or, maybe, same idea but with an LM3914 dotbar driver, do a dac to run voltage from 0 - 5 volts. 3914 can fire transisto...
by anhingus
Thu Sep 30, 2010 5:05 pm
Forum: SparkFun Product Questions
Topic: interesting project
Replies: 5
Views: 820

Re: interesting project

this is an intricate question. do you program in c? do you have any electronics experience? are you in a hurry? if you don't program, i would go the coridium armmite board and program it in basic. handling 110v with a relay, no problem. coridium has analog to digital convertors so no problem with st...
by anhingus
Wed Sep 29, 2010 11:34 am
Forum: SparkFun Product Questions
Topic: Wall wart and breadboard power kit
Replies: 6
Views: 930

Re: Wall wart and breadboard power kit

if you want a choice of 5v or 3.3v go with the 9v wallwart. voltage regulators are active voltage dividers and need an input higher than their output. you can use a regulated wallwart to power a breadboard but the LM317 in the kit will give you better voltage regulation and less noise in your circui...