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by komarek
Sun Jul 30, 2017 8:39 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

rpdom wrote:
Sun Jul 30, 2017 8:32 pm
komarek wrote:
Sun Jul 30, 2017 8:13 pm
why in your computing you considered the current as 0.01?
the AC is actually 1 Amp
No it isn't. That might be what the PSU can supply if needed, but it isn't what the LED will use. 10mA is reasonably for an LED.
:D
sorry
noobs questions...
by komarek
Sun Jul 30, 2017 8:13 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

Just put a resistor in series with the LED. The LED is a diode so it will only conduct and light up for one half cycle of the supply. The peak voltage of an AC supply is 1.4 times the quoted RSM value. 1.4 * 12 = 16.8 volts. The LED when it lights up will have a "forward voltage" across it. Say 2 v...
by komarek
Sun Jul 30, 2017 8:11 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

Just put a resistor in series with the LED. The LED is a diode so it will only conduct and light up for one half cycle of the supply. This is bad advice, most LEDs have a maximum reverse voltage rating of around 5V so simply using a series resistor when connected to 13Vac will do the LED no good at...
by komarek
Sun Jul 30, 2017 6:27 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

Just put a resistor in series with the LED. The LED is a diode so it will only conduct and light up for one half cycle of the supply. The peak voltage of an AC supply is 1.4 times the quoted RSM value. 1.4 * 12 = 16.8 volts. The LED when it lights up will have a "forward voltage" across it. Say 2 v...
by komarek
Sun Jul 30, 2017 11:11 am
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

About the led

Is there any simple way to turn a led on with a 13VAC circuit?
by komarek
Sat Jul 29, 2017 4:40 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

LOL

probably you won't like it but i solved my problem of triggering GPIO 4 with a similar solution as opto-isolator. i've connected a led to the rectified-AC circuit (supposed to be the bell ringing) and.. on the other side the gpio 4 is connected to a ldr sensor... so when the led turn on.. the ldr ge...
by komarek
Sat Jul 29, 2017 2:08 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: OK SO

. Probably it's a better solution Why do you think so? Optoisolator is like a relay with no moving parts, much higher reliability. Also you may have problems with a relay on AC -- some will try to buzz at the AC frequency, so you need rectification anyway. i don't have an optoisolator now. i ordere...
by komarek
Fri Jul 28, 2017 10:07 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: OK SO

i need to improve myself to understand what a opto-isolator is :) An optoisolator has an LED and a phototransistor in one package, optically linked. Used correctly (needing a simple diode, a current limiting resistor and probably a capacitor), the LED will light when the 12V is on (NB you didn't pu...
by komarek
Fri Jul 28, 2017 9:46 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: OK SO

How far is it from the PSU to the Pi? How thick is the cable? Have you calculated the voltage loss on that cable, at the current expected while the Pi is operating? It might work if the DC-DC converter is at the Pi end, but it might not. It won't work if the converter is at the PSU end. it's quite ...
by komarek
Fri Jul 28, 2017 9:18 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

the SCHEME
by komarek
Fri Jul 28, 2017 9:05 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

OK SO

the last question. i've found a good DC-DC converter... and i powered the Pi0 through the gpio with it.. and it's working pretty well. Now the last part... cause i need to interface the same PSU on its AC output to control GPIO 4 of the PI. so from the same PSU i have 5V to power the Pi0 with a DC-D...
by komarek
Fri Jul 28, 2017 6:37 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

Remember that absolute voltage ratings for USB are between 4.75 and 5.25V (+ or - 5%) so even six volt is way to much! In fact the PI's that do have over-voltage protection short the 5V line to GND if the 5V line goes to 6.0Volt or higher, and then the (poly) fuse blows. So yes putting 6.0Volt on a...
by komarek
Fri Jul 28, 2017 6:34 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

I think I would forget about the 8v output. Not enough current. Personally I would put the 12v AC through a bridge rectifier, followed by a smoothing capacitor. That will get me a 16.8 volt DC supply. Which will droop badly with load. Never mind. See here for the general idea: http://www.electronic...
by komarek
Fri Jul 28, 2017 6:00 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

I'll regret this, but I can't resist... i do have an official PSU but i can't plug it to 220V the only psu i have in the place i want to put the PI is the one i've posted in the picture If you can supply the pictured PSU with 'mains' electricity, why can't you use that same mains supply for the 'of...
by komarek
Fri Jul 28, 2017 5:43 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: actually

i am thinking about to connect the 5V 0.37A output of the Dc-Dc to the 5v-GND gpio of the Pi... what u think about that? BUY AN OFFICIAL PI PSU. Sorry for shouting, but you don't seem to be getting the message. i do have an official PSU but i can't plug it to 220V the only psu i have in the place i...
by komarek
Fri Jul 28, 2017 5:25 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

In your initial post you stated: i'm having my power source by a 12v DC and 0.3A power supply... then i used a stepdown DC-DC converter to have a 5v DC output. I wonder what would be the behaviour of your DC-DC convertor if it was actually given an AC (alternating current) input? Since the supply w...
by komarek
Fri Jul 28, 2017 5:24 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: actually

i took the measure with the multimeter and the PSU produces 0.37A and not 0.2 as written. and 7.75 DcVolts. not 8 on DC and 13.35 AcVolts. not 12 on AC So why have we been talking about 12V and 0.3A? In any case the DC output is only marginally adequate, even for a Pi0 and using a 100% efficient co...
by komarek
Fri Jul 28, 2017 5:12 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

actually

i took the measure with the multimeter
and the PSU produces 0.37A and not 0.2 as written.
and 7.75 DcVolts. not 8 on DC
and 13.35 AcVolts. not 12 on AC
by komarek
Fri Jul 28, 2017 4:57 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

btw this is my PSU

check the image
Image
by komarek
Fri Jul 28, 2017 4:43 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: OK NOW. i have a new Pi Zero

So your psu supplying 12v at 0.3A should be able to supply it, BUT if the psu is actually a battery charger it is quite possible that it will not supply 0.3A at 12v, to test your set-up with out risking your pi you could connect a resistance of 17 ohms ( rated at 1.5watts) and then try measuring th...
by komarek
Fri Jul 28, 2017 2:32 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: OK NOW. i have a new Pi Zero

I would suggest you replace the DC-DC converter with one that has a variable output so that you can set it at 5.1V and is capable of supplying 1A minimum. if you try to re-use the same DC-DC converter as you did last time you could very well destroy another pi. well this converter is actually varia...
by komarek
Fri Jul 28, 2017 10:37 am
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: OK NOW. i have a new Pi Zero

RaTTuS wrote:
Fri Jul 28, 2017 10:33 am
that's far too low
you need 5V @ 1A [less will work on a Pi0]
it is a pi zero w
and i m worry about to burn it as i did last time
by komarek
Fri Jul 28, 2017 10:13 am
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

OK NOW. i have a new Pi Zero

and this is my situation
the dc-dc voltage regulator produces 4.7V at 0.2A
and i need to power my pi zero
i need to decide how to do that. obviously i don't want to burn it again.

what do you suggest to be safe? some capacitor?
by komarek
Thu Jul 20, 2017 7:43 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

As old carpenters and/tailors used to say "Measure twice, cut once." Never trust that some random cable has red = plus volts, black = 0v. Or that the voltage is what it is supposed to be. It takes seconds to check with a multimeter. I bought some microUSB breakout boards on ebay. They are handy for...
by komarek
Thu Jul 20, 2017 4:39 pm
Forum: General discussion
Topic: Bricked my Pi. don't know why
Replies: 121
Views: 12430

Re: Bricked my Pi. don't know why

i see but excuse me one question... the Raspberry doesn't have a circuit for protection about these voltage fluctuations through the micro usb port? The device started to burn and smoking. sounds too much for 1 or 2 volts difference No the pi zero does not have any input protection unlike the pi2 o...

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