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 1 Using Arduino / General Electronics / Re: power leds driver on: March 09, 2014, 09:03:03 pm Quote from: Chagrin on March 09, 2014, 08:48:04 pmQuote from: cjdelphi on March 08, 2014, 05:17:05 pmI'm not saying you should, I'm intrigued by fungus' s comment, It's not as wasteful as he might think.(Vin - Vf(LED)) * I = power wasted. You can make up any arrangement of mosfets, bjts, or resistors that you like but the above formula still holds true. I'm refering to the waste of the transistor (heat dissipation) ...
 2 Using Arduino / General Electronics / Re: power leds driver on: March 09, 2014, 04:38:49 pm Everycircuit for android and ios....
 3 Using Arduino / General Electronics / Re: Hot/Cold Fault Finding... on: March 09, 2014, 10:43:13 am Why would it?Stick the electronics in a freezer = never break?
 4 Using Arduino / General Electronics / Hot/Cold Fault Finding... on: March 09, 2014, 09:41:08 am I found this video interesting, now i'm curious as to why the ceramic capacitor seems to spring to life when it's cooled down?...(I can't imagine this technique working on an electrolytic)
 5 Using Arduino / Microcontrollers / Re: Measuring VCC with an Attiny 85 on: March 08, 2014, 10:37:23 pm Quote from: Coding Badly on March 02, 2014, 07:11:09 pmUgh.  More bad pennies.Code:  result = 1125300L / result; // Calculate Vcc (in mV); 1125300 = 1.1*1023*10001023 is not correct.  The correct value is 1024.http://arduino.cc/en/Tutorial/ReadAnalogVoltage0 - 10231 - 1024The tutirial div's by 1023 ...  if a value of 0 is returned then it's div 1023 not 1024?Moderator edit: quote trimmed
 6 Using Arduino / General Electronics / Re: power leds driver on: March 08, 2014, 05:17:05 pm Quote from: db2db on March 08, 2014, 03:49:32 pmQuoteReplace the fet with an npn ...What's changing to an NPN do for us?  For us?....I was talking to fungus, using the n channel fet you need to apply 20 volts or so according to my simulation,  which concurs with  the indestructible's thread...Switching to a bjt means you can significantly drop the voltage and still power the LED.I'm not saying you should, I'm intrigued by fungus' s comment, It's not as wasteful as he might think.
 7 General Category / General Discussion / parasitic ram explot.. on: March 08, 2014, 09:55:07 am http://wp.josh.com/2014/03/03/the-mystery-of-the-zombie-ram/Change the led for a capacitor, avoid eeprom completely?  But is it damaging?
 8 Products / Arduino Due / Re: Operating Voltage for components on: March 08, 2014, 09:25:22 am Gnd/5v (to power the sensor) is fine from the due...What's not fine is the 5v logic signal, you will need to step it down... zener, voltage divider, regulator before it's fed back to the due.
 9 Using Arduino / Project Guidance / Re: calling all experts - need a bit breaduino help... on: March 08, 2014, 09:12:58 am The two caps on each side of the crystal, you only have 1 correctly seated.
 10 Using Arduino / General Electronics / Re: Control 3 LEDs with 2 pins on: March 08, 2014, 06:40:27 am http://electronicsclub.info/cmos.htmA 4028 binary to decimal decoder ic will do the job... the other way might be to use logic gates and build your own.
 11 Using Arduino / General Electronics / Re: power leds driver on: March 08, 2014, 06:28:23 am Quote from: fungus on March 07, 2014, 09:38:20 amQuote from: jimbarstow on March 07, 2014, 09:15:29 amThis series has a great explanation of the different ways of driving a power led. There is also a really simple design for an efficient driver. That driver may be simple, but it's not efficient. It will waste as much power as a resistor.Replace the fet with an npn ...What's your complaint with this type of circuit?... inefficient how (for what it does)
 12 Using Arduino / General Electronics / Re: input voltage = forward voltage = no resistor required? on: March 06, 2014, 09:54:05 am http://flashlightwiki.com/Driver#Direct_DriveQuote Direct Drive17mm linear regulator driver with 4 7135 chips and microprocessorIf you apply the correct voltage, you don't need a driver at all. Lithium-ion batteries conveniently provide a decent voltage without any further modification. This is quite efficient since all of the power from the battery is delivered to the LED. However a fresh li-ion battery starts at 4.2 volts fully charged and will be 3.6 volts when it needs to be recharged. As power is applied to the LED, it will draw a certain amount of current from the battery. This current increases with the voltage. When the voltage is higher, the LED will be very bright and draw a great deal of current. As voltage decreases the light will dim and draw less current. If a constant brightness is desired, a driver that offers some kind of regulation is required. Also, many LEDs are being overdriven by 4.2 volts of a fresh li-ion battery. next you'll be telling me, all flashlights without constant current regulators will kill the LED.... Next you'll be telling me, my flashlight no longer works  because there's no current limiter in place, just a flashlight, LED and the body (ie, the heatsink) and i've used it > 500 hours.The heatsink prevents it from getting hot enough to self destruct, something this LED string lacks... and i agree, current needs to be limited.You probably don't agree with that either....  but there's PLENTY of people in the flashlight world who would tell you, you're talking crap when you say you need a constant current driver for ALL LED'S this is simply un freaking true.
 13 Using Arduino / General Electronics / Re: input voltage = forward voltage = no resistor required? on: March 06, 2014, 09:48:15 am Quote from: retrolefty on March 06, 2014, 09:38:35 amAnd still the rubbish continues!it's only rubbish if it's untrue.And are you now going to claim that i never actually did this test and experimented with temperature ? even though i've had a 5mm LED running for days on end monitoring current and voltage? did it blow up after a week? no..Did i place the LED in an unknown environment where it could get hot and self destruct? no... Am i claiming it's safe to run it at it's max current to do this?.. no...So it's not rubbish, it's fact...   do i need to create an Arduino project to monitor the heat in the room and current draw over a range of temperatures and log the data ?Which part are you failing to agree with?
 14 Using Arduino / General Electronics / Re: Solid State Relay, but normally closed on: March 06, 2014, 09:42:04 am a prebuilt, SSR (ie one you're not making yourself using a TRIAC) should already have an optoisolater for the low voltage DC side to switch the 240/120ac side right?.so as already suggested, use transistors to keep the SSR normally closed.