Re: Controlling A/C remotely (what to use?)
Even without a RPi, you should be able to use your PC to record and playback remote codes. Once you've verified this works with your A/C, you can copy the remote codes into the RPi's software....
Andyy
Member
Last Activity: 10-05-2021, 06:27 AM
Joined: 08-12-2016
Location: Sydney, NSW
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Re: EEPROM function confusion
It's probably the change from cold-to-hot, or hot-to-cold, rather than the absolute temperature, that makes faulty/going-faulty semiconductors exhibit weird behaviours.
As for a TV failing to boot, my guess is that the main microprocessor is reading an out-of-range value from the EEPROM....Leave a comment:
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Re: Arduino current sensing (in car)
Yep, it is exactly the optocoupler equivalent of hFe transistor current gain. CTR = Current Transfer Ratio. For an example of a high gain optocoupler, look at the datasheet CTR for a 6N138.
Incidentally, you can replicate the darlington in the 6n138 by connecting an external transistor to a conventional opto....Leave a comment:
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Re: Arduino current sensing (in car)
Yep all good. Obviously there's no such thing as a "350 ohm" resistor, so use the nearest one higher, 360 ohms. Even 470 ohms should work, it's not that critical.
As for burning one out, I guess you don't accumulate broken e-junk for component salvage like I do
(I've got heaps of optocouplers from modems, power supplies, etc.)....
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Re: Arduino current sensing (in car)
The resistor is probably too high. Calculate a new resistor using the standard LED forward voltage drop 1.2V for a LED current of 15mA, or use the values in the optocoupler's datasheet.
Also on the transistor side, connect emitter to GND, collector to 1k resistor, other end of resistor to 5V. Use your multimeter to monitor the collector voltage as you push the button (the voltage should drop from 5V to 0V)....Leave a comment:
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Re: Buying custom crystals...
Have you tried getting a free sample from silabs?Leave a comment:
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Re: Buying custom crystals...
You need this
[url]http://g4oep.atspace.com/channels/channels.htm[/url]
Re: Buying custom crystals...<br />
...r />
<br />
;)Re: Buying custom crystals...
You need this
[url]http://g4oep.atspace.com/channels/channels.htm[/url]
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Re: LM317 constant current question
On a related note, you can also use 7805, 7812, etc, and their negative voltage counterparts as current regulators in the same fashion. Just need the appropriate resistor.
Boosting the current capability of a regulator with an external high-powered pass transistor is also possible with the current regulator circuit topology, though your series resistor by this stage is going to be dissipating a fair few watts
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Re: FM Jammer project
If it's FM radio and you're broadcasting just a carrier with no modulation, you'll actually mute the radio....not cause static....Leave a comment:
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Re: Detecting A Bullet
I remember an episode of Mythbusters [url]http://www.youtube.com/watch?v=2qY0DA7DG9s[/url] where they used a simple apparatus consisting of two pieces of foil separated by a thin insulator (like kitchen cling wrap film). When the bullet pierced the foil and insulator, the foil would make contact with the other foil, closing a circuit.
I'm not sure if it's adaptable to your scenario though.Re: Detecting A Bullet<br /> <br />...mple apparatusLeave a comment:
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Re: Isolated transformer ?
If you can find a couple dead computer UPS, you can extract the transformers and wire the secondaries to each other. Choose transformers from higher VA rating, and derate when using.Leave a comment:
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Re: UA741 op-amp power supply question
Here's another power supply circuit using an op-amp and pass transistor, with current limiting.
[url]http://www.eevblog.com/forum/projects/90s-vintage-boxed-dick-smith-power-supply-kit-(k-3206)/[/url]Re: UA741 op-amp power supply questi...k-3206)/[/url]Leave a comment:
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Re: Could you do this?
You'll still need UPS with generator automatic change over switch. Because the generator can't start up instantly after mains failure, the UPS provides power for a few minutes while the generator starts and warms up. As soon as the generator voltage has stabilised, the UPS switches to generator power....Leave a comment:
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Re: Could you do this?
The standard components in a UPS (transformer, switching FETs, heatsinking, etc) weren't designed for continuous operation in mind. Even extended operation may stress a borderline cheaply designed Chinese UPS (yes, I'm using that as a generalisation) to the point of failure.
As others have pointed out though, APC UPSes certainly seem to be tolerant of this kind of modification....Leave a comment:
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Re: Samsung UN55C9000 dead
You don't need a schematic. Instead of guessing, you can go through step by step systematically. Start with the the suggestions outlined in the previous posts above.......Leave a comment:
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Re: Can I but any board for my Samsung Tv
MacGyvering stuff works sometimes! [url]http://www.youtube.com/watch?v=gSzfNrbDfIY[/url]Re: Can I but any board for my Samsu...fNrbDfIY[/url]...Leave a comment:
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Re: Samsung PN64E550D1FNZA
Also shopjimmy's kit does NOT contain RS833 and RS819. These are 47Ω 0.125watt (0805 surface mount package) gate drive resistors for QS802 & QS804. I found both my gate drive resistors open circuit when I repaired my board. If you can't get 0805's you can squeeze 1206's onto the pads. DON'T use 0603's as their power rating 0.1watt maybe insufficient....Last edited by Andyy; 08-29-2016, 09:48 PM.Leave a comment:
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Re: Forcing on Power Supply with PS_ON
Borrow a car battery and inverter...
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Re: Forcing on Power Supply with PS_ON
If your scope is battery powered, you won't need an isolation transformer (effectively the scope is a fancy glorified multimeter, whose ground reference is floating).
But an isolation transformer is good anyway for safety's sake.Leave a comment:
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Re: Samsung PN60E7000FF No Power, No Standby- SMPS Component Question
I would've tried downloading the firmware had it been my TV
But I've since returned the repaired TV (shorted QS802 & QS804) to my friend, so I can no longer play around with removing the microcontroller and downloading the firmware....
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