![]() The dht11 sensor can work from 3 voltage to 5.5 volts. When the resistance is maximum at the test pin, the circuit shows zero volts across the voltmeter, which means the sensor is either in the dry ground or taken out of the ground i.e. My Macbook Pro battery had run down (it does quite a bit) so I rebooted with the power inserted.Dht11 Temperature And Humidity Sensor Library For Proteus. I get a frozen screen saver which is normal, while the progress bar finds it feet back on power. However this time, I had the frozen screen saver, and a continuous 3 beeps which I've never had before in a loop? I then re-pressed the power switch on the Macbook and it rebooted fine and seems ok. MacBook Pro i7 8GB - iPhone 4, Mac OS X (10.6.7) MacBook Pro :: 3 Beeps On Start Up? I then booted up this morning with a full battery and the boot up took a lot longer than normal - maybe around 3 minutes on the spinning logo, and then finally booted - are these all worrying signs? This i7 is coming up to its first year (which I think is covered by Apple?) and I *think* this maybe a memory issue? If it is, and my Mac is covered, then by a sheer stroke of luck, I decided to get Apple to fit the 8GB memory at the time of purchase (bad I know! and I don't usually do that) BUT that would mean that Apple fitted the memory upgrade and I haven't touched anything myself. ![]() I'm working on a Macbook pro 15 A1278 for a friend. They were given the computer by someone who didn't want it. My friend did not have the password to get into the machine and no original system disc. I thought this was going to be an easy case of erase-and-install. So I attempted to boot from my own Snow Leopard DVD, then I started getting three beep errors. Now I can't get as far as the password screen any more. Computer starts with normal chimes, then when it gets to the grey screen with the Apple, I get the 'three beeps'. Bought new ram, put it in, reseated it a bunch of times, still three beeps every time.Attempting to restart using the system DVD by holding the C key, same problem. ![]() Fired the machine up as a target disk and ran disk utility via remote control from another machine, we'll call that one 'machine B'. Hard drive checks out with no errors and is formatted in Extended Journaled. ![]()
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