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61  Using Arduino / General Electronics / Re: N-power Mosfet pc fan control. on: August 04, 2014, 09:52:32 pm
You sure you're using a n channel mosfet?  The pull down resistor is important to keep the damn thing off.

62  Using Arduino / General Electronics / Re: Simplest single-cell supercap charging circuit? on: August 04, 2014, 09:09:19 pm
Why not an adjustable ldo?  Eliminating the need for a zener..

63  Using Arduino / General Electronics / Re: 220VAC to 12DC on: August 04, 2014, 09:18:21 am
To the people claiming no.... what is safe? Or what makes it safe?  ..

To me safe is having isolation between you and mains supply, which is what the power supply you had, let's suppose something fails  high voltage side, the transformer will at worst short and get hot, a fuse is the obvious answer.. but the human lives even when touching the device being powered...

Gaps, distance between tracks, bad design for sure but not (can't be) all chinese manufactured  produce the same power supplies...  kinda makes me want to design my own.

So what are the rules for a safe power supply from mains? Spend at least $50 with a brand name? Do usb chargers from apple, samsung fail? Explode? I bet they do...
64  Using Arduino / General Electronics / vibration sensors.. on: August 03, 2014, 10:54:47 pm

I won 10 of those on a 90c bid! Free postage too.

The flimsy wire threw me off, I thought that tiny wire simply got knocked around touching the other pin/leg, it seems that it really is juat a flimsy leg and the shake internals do the real job.

It should be ok to mount one in a letter box to detect the postman? He has to lift the top up to put letters in..
65  Using Arduino / LEDs and Multiplexing / Re: Way to cheat 74HC595 maximum continuous operating current? on: August 03, 2014, 10:01:21 pm
Uln2003 in combo with the 595 will result in a lot less wires than using bjts.
66  Using Arduino / Sensors / Re: Protecting the AD pins on: August 03, 2014, 09:56:57 pm
And r3 is there to limit current to the ad pin if all else fails.

Well it's then much too low a value as if and when the ADC internal clamping diodes conduct they are rated at less then a milliamp before damage can result.

There is no such protection that covers 'if all else fails'.  smiley-wink

A 1ma blowable fuse? smiley
67  Using Arduino / Sensors / Re: Protecting the AD pins on: August 03, 2014, 09:03:58 pm
I guess you can use the tvs either end?   Eg 5v on the input to arduino, 16v on the input/resistor divider.

Yes sorry I'm often mixing zener with schottky,  they look similar to me, what's the purpose of the schottkys? I'm curious
68  Using Arduino / Sensors / Re: Protecting the AD pins on: August 03, 2014, 08:26:31 pm
So you have  a resistor divider then a zener to clamp down...

The zener on the vcc line serves what purpose? ... zeners are slow which could be why you keep blowing adc ports ?  Buy a coupke TVS diodes instead to protect the arduino.  clamp it  to say 16v on the input making sure the resist divider does it job
69  Using Arduino / General Electronics / Re: 220VAC to 12DC on: August 03, 2014, 03:47:26 pm

Do NOT buy that module!
It have almost NO INSULATION gap!

From another forum

Rat97, remember my retire

OK AWOL I give up but you forgot Beatles and Richard Branson. Let's stop here, this is rat97's tread.


Interesting, i though that thoose are the modules what are inside adapters....

They are!   And they are the better of the el cheapo ones too which are capacitor fed. My rule for using cheap power supplies is simple don't use them for anything you'll need to touch or handle, treat them as works of art, always disconnect power before touching what the power supply is powering...

The one you posted should be fine because it's isolated with the transformer if anything fails...

70  Using Arduino / General Electronics / Re: Extending battery life on: August 03, 2014, 03:37:35 pm

Aussie dealers are the worst on ebay lol
71  Using Arduino / General Electronics / Re: How screwed am I? (Failed solder attempt) on: August 03, 2014, 03:28:51 pm
Oh wow, that soldering job brought back memories smiley

When you can, dump it and go for a temperature controlled station with esd protection.  Those header pins  smiley-eek-blue  if you wanted to, scrape off the silk screen to get at the pcb tracks and if you really wanted to use jumper wire to repair them, it's time consuming though.

72  Using Arduino / General Electronics / Re: Cheap Soldering Iron Problems on: August 03, 2014, 03:20:40 pm
[quote auwantr=dave-in-nj link=topic=258653.msg1828648#msg1828648 date=1407077857]
If my soldering station fails how do I repair it   smiley-eek

depends on how if fails.  if the dog chewed the cord, just replace the cord.
if the tip is corded and not making contact, clean the contacts
if the fuse blew.... I guess we could do this all day.
many irons are just a transformer, a heat sensor and a triac.   find out what is not working and you will probably figure out how to fix it.

As in I can't repair it because I need a soldering iron!   Obviously what you suggested are the first things I'd check...

take a breath,  facts, we can only deal with facts.  'broken' is not a description.  "i'd check" if a future tense of a verb.

voltage meter.  has no operational requirement that includes a working soldering iron. use it, find where the power stops.

since a soldering iron is a cord, a handle and a heating element, there is little to stop it from working.  also, most are made of steel so rusting occurs.  cleaning is required. 

make, model, photo, findings of testing....   


Huh? You want facts for a non broken soldering station?
73  Using Arduino / General Electronics / Re: 220VAC to 12DC on: August 03, 2014, 09:18:35 am
Then buy a small 500ma usb phone charger! 

Feed the 5v into the 5v (I think vin goes to the regulator) of your arduino.

74  Using Arduino / General Electronics / Re: 220VAC to 12DC on: August 03, 2014, 08:46:30 am
Smaller?  There are compact usb power supllies ... 9v a must?
75  Community / Website and Forum / Re: Too much spam ! on: August 03, 2014, 08:40:31 am
On some forums you can set it up so your first post is shown once approved by mod...
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