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31  Using Arduino / Programming Questions / Re: Convert voltage to dB on: October 03, 2014, 12:50:12 pm
The formula is fine. Maybe you should print some of the sensor values and work things out by hand.

32  Using Arduino / Programming Questions / Re: Convert voltage to dB on: October 03, 2014, 11:08:56 am
You probably need to cast sensor value to a float so that the division is done in floating point.
33  Using Arduino / Programming Questions / Re: Convert voltage to dB on: October 03, 2014, 09:53:18 am
The *second* hit if you google "ln" tells you it is the natural logarithm. (i.e., base e, not base 10)
34  Using Arduino / Programming Questions / Re: Accessing memory on: October 02, 2014, 05:50:00 pm
Use the EEPROM, not the FLASH.
35  Using Arduino / Microcontrollers / Re: Does touching atmega328 pins dandifies te chip? on: October 02, 2014, 05:34:37 pm
If you aren't taking static electricity precautions it is possible to damage the chip, even though they have ESD diodes.
36  Using Arduino / General Electronics / Re: Measuring a small difference in resistance on: October 02, 2014, 09:53:54 am
If you have to measure them to 1% they are not there for "immunity to transients"!

You need to measure the resistance *without* the resistors in the circuit to see how much parallel resistance is there that might influence the measurement.
37  Using Arduino / General Electronics / Re: 104nF 50v decoupling capacitor that burns on: October 02, 2014, 09:31:35 am
I was thinking more of a power supply oscillation - still unlikely, but more power available! 8^)
38  Using Arduino / General Electronics / Re: Measuring a small difference in resistance on: October 01, 2014, 05:07:52 pm
Is the resistor totally isolated? It does not take much parallel resistance to mess up a 1% measurement.
39  Using Arduino / General Electronics / Re: 104nF 50v decoupling capacitor that burns on: October 01, 2014, 02:17:18 pm
Check it with an ohmmeter to make sure it is really a capacitor.
40  Using Arduino / General Electronics / Re: 104nF 50v decoupling capacitor that burns on: October 01, 2014, 12:34:21 pm
The only time I have seen something like this happen is when something oscillated and sent too much AC current through the capacitor at a frequency where the ESR is high.

Unlikely in this case, though.
41  Using Arduino / General Electronics / Re: Noob Question about Transistors on: September 30, 2014, 10:12:02 am
If he is asking what I think he is asking, then yes the voltages must "match".

If you have 50 V on the collector and 20 V on the emitter, you must have about 20.7 V on the base to turn it on. You cannot apply just 0.7 V to the base.

Relays are different, since they are electro-magnetic-mechanical devices with no electrical connection between the coil and the contacts, there is no real limit to the voltages. The coil can be at 0-5 V, and the contacts at 100-200 V.

Safety, don't try this at home yadda, yadda yadda.
42  Using Arduino / Programming Questions / Re: shiftOut() on: September 29, 2014, 01:27:56 pm
If you don't like this behavior, feel free to write your own function that acts in the way you require. General functions that interface to hardware can not be expected to work in all situations.
43  Using Arduino / Programming Questions / Re: name look up of 'x' changed for new ISO 'for' scoping on: September 25, 2014, 02:18:41 pm
Are you familiar with the Monty Python "Dead Parrot Sketch"? After it goes out of scope a variable is dead, pining for the fjords.
44  Using Arduino / Programming Questions / Re: Sine Waves on: September 25, 2014, 02:09:32 pm
Just make sure you go only 2*PI radians and then stop.
45  Using Arduino / Programming Questions / Re: Declaring multiple Pins to one int? on: September 25, 2014, 10:59:02 am
Unfortunately,
Code:
X = 1,2,3;
is perfectly valid syntax.

But it does not do what you want. google comma operator.
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