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166  Using Arduino / General Electronics / Re: Using a 5v pin to power a 3.3v volt device on: July 30, 2014, 10:06:42 pm
Ahh.. after looking again lol (at the wav player this time)

Forget the pass resistor!

3.3v ldo from 5v.
167  Community / Products and Services / Re: Shameless ad for EveryCircuit. on: July 29, 2014, 12:55:03 pm
@cjdelphi into the community search box, my public circuits will show up  smiley-eek
168  Using Arduino / General Electronics / Re: Using a transistor instead of a relay as a button on: July 28, 2014, 10:11:48 pm
Why am I confused as hell from this post.....

Use a transistor instead of relay, yeah no problem... then I get lost due to a resistor between arduino's pins.... maybe it's the lack of provided circuit throwing me..

So are you sensing the 12v voltage?  Then acting on it?  Do you wish to provide 12v from a transistor (a switch?)

169  Using Arduino / General Electronics / Re: Switching the Dimmer 'on' and 'off' affects my computer on: July 28, 2014, 12:13:14 pm
Even a picture of a hand drawn diagram will be good, in jpg, png or pdf format.

I noticed. When the computer makes that beep sound, I stopped receiving data from the Arduino in my Matlab GUI. Thanks

240v linked to ground?

Normally I'd have said the relay's emf is to blame, but the last circuit you posted suggests mains voltage is shared.
170  Using Arduino / General Electronics / Re: transformer's centretap. on: July 27, 2014, 06:02:44 am
I was close enough, the answer is what i dreaded you'd say...  thanks seeing it is you. 
171  Using Arduino / Project Guidance / Re: Car power supplying Arduino?? on: July 27, 2014, 06:00:41 am
it sounds like something's drawing too much current already that or the battery simply can't provide the cca required to crank over the engine, the start motor could be also on it's way out? whatever the cause...

I think trickle charging a small battery so it's under it's own power when the alternator is off this gives a UPS effect.
172  Using Arduino / General Electronics / transformer's centretap. on: July 26, 2014, 12:25:20 pm

In all of the inverter circuits I've seen they all have a ct pin, on a transformer without one, I presume  I have to energize the entire primary coil at 50hz ?
173  Using Arduino / Project Guidance / Re: Need to make an audio amp, maybe with lm386 on: July 26, 2014, 01:00:45 am
.5watt speaker will sound tinny at best regardless of amp...

Is the lm386 not automatically set to a gain of 10? / .25watt? Sounds ideal, you can change the gain higher and use a pot on the input signal.
174  Using Arduino / Project Guidance / Re: Is 5.5volts from external regulator to Vin pin enough?? on: July 26, 2014, 12:57:45 am
Ideally 7-7.5v
175  Using Arduino / General Electronics / Re: Arduino Due + LED Resistor Requirements on: July 25, 2014, 06:43:38 pm
The due has the least voltage/current vs say an uno eg 3.3v vs 5v

So you're not going to get very brightly lit LED's are you using 5mm uv leds or more powerful ones?
176  Using Arduino / General Electronics / Re: arduino-18650 charger-help. on: July 25, 2014, 06:38:54 pm
You wish to charge the connected batteries to arduino?

Except, you require > 8v  to charge 2 batteries in series, and then it becomes tricky, charging 2 individual batteties via 5v is the easier option.
177  Using Arduino / Project Guidance / Re: Using LDR as a alert at anytime during program on: July 25, 2014, 12:15:09 am
I don't unde and how you mean you can send it once?

Why not call xively before the twitter post? The code I understand but the system ie how to post tweets, what are the steps involved!
178  Using Arduino / Project Guidance / Re: Car power supplying Arduino?? on: July 25, 2014, 12:04:14 am
The car has a average voltage of 14.4vdc, and will not start below 13vdc. 



Average voltage is 14.4v is it?
Car refuses to start under 13v

And who took these measurements?   Average voltage from the alternator is around 14v the car would have issues if the battery read 11.5v (starting it) but 12.5v to 13v is plenty to turn the starter motor...

 your values seem off.
179  Using Arduino / General Electronics / Re: What areas of electronics are useful to learn about for arduino projects? on: July 23, 2014, 12:29:44 pm
I once had a teacher/supervisor who grumbled on about how students now just use an mc to do the work over the use of good old logicchips...

I guess it boils down to what you want to do, no point learning about low pass filters if all you want to do us blink an led and make it go beep
180  Using Arduino / General Electronics / Re: Wind generator for 12v battery - no controller? on: July 23, 2014, 11:17:15 am
The turbine can supply peaks higher than 14.5v but the current is lacking to do any real damage. Since the motors rated for lead acid it will produce aroind 14-18v with a light load, but the battery will suck up the current and not go over, unless it happens to produce stupid amounts for current/voltage..

People use 240vdc rectified and fed into 12v batteries to "regenerate" them... as long as it does not boil and run out of water/acid it's practically happy

But sticking a 14.5v switching regulator on the output is the best way for a lead acid.

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