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1  Using Arduino / General Electronics / Producing negative voltage. on: Today at 10:02:32 am

I'm a little puzzled as to why the cap is thrown below 0v  .. why does it not stay 0v?  Maybe it's because I've barely slept and it's going straight over my head...

2  Using Arduino / General Electronics / Re: Charging 2.7v supercap with 5v but monitor with analogRead() on: Today at 07:46:37 am
I have several 150+ farad caps, I've not put them to use because of the large current drain..

2.7v is not really enough to power an Arduino 2 caps in series to get 5v then regulate it, with arduino you charge via pwm and a power transistor, stop charging, wait a second then read the voltage,  check  if voltage  is correct, if not repeat...

3  Using Arduino / General Electronics / Re: relay board for arduino on: Today at 03:55:41 am
Those boards come with drivers for the relay, so little current per pin is required...

The link you posted is opto controlled, requiring a low/gnd signal to trigger it off, the relay breakouts vary..
4  Using Arduino / General Electronics / Re: Breadboard Alternatives or Next Steps? on: July 30, 2014, 10:24:36 pm
I guess after proto/strip board..

It is possible to simply draw onto copperclad, you draw the tracks, pads, etc and then it's a case of etching the board and soldering the components...
5  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.
6  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
7  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?)

8  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.
9  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. 
10  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.
11  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 ?
12  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.
13  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
14  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?
15  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.
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