I mean, I know the formula.. (U=IR), and I know that you need to add resistance to avoid blowing your sensors. But what I don't know is how can you now upfront by how much? (generally speaking btw)
Lets take the microphone as an example, here are the specs of the mic
It should provide me with all the information I need, but I dont know how to determine from this the amount of resistance I should provide.
Besides.. the given electret microphone says it need 1,5V and a current of 0.5mA. I know my Genuino provides 5V and around 40mA... so can these numbers give me some guidance on how to choose the amount of Ohms I add?
jremington:
The specification sheet says to use an external resistor of 680 Ohms.
You will need an amplifier to make use of that microphone. There are a variety of convenient microphone modules with one built in, like this one.
Thanks for the info, but are you certain that those are the right amount of Ohms? If I look at the sketch correctly.. then I would need 680 Ohms if I have a power supply of 1,5V. Or am I reading it wrong?
And another thing.. why are the people in the tutorial (http://www.instructables.com/id/Simple-illustrated-Clap-Switch/) using a 10kOhm resistor? I mean.. they are probably having more voltage as input.. but then, how does this voltage/resistance scale for this sensor? Not linearly I suppose, right?
(Sorry if I am asking really stupid questions, but this is somewhat new for me.. and I try to get a clear understanding on how to work with sensors in general, such that in the next time I will have enough info using only the specification manual)
The clue is in the name "instructables" most electronic ones are written by idiots who have no clue as to what they are doing. Never use this website unless you know more than the authors.
Omni-Directional Foil Electret Microphone, 9.7 mm diameter and 4.5 mm high, Power Supply 5.0 V max, External Resistance Loading of 680 Ohms, and sensitivity of -44 dB.
But you will need an amplifier.
I agree with Grumpy_Mike that Instructables is almost always an extremely bad source of advice. Most people who post there have no idea what they are doing.
I am at work atm... so do you guys have any pointers on what kind of transistor/amplifier to use? Because then I can read that when I get home.
Or a place where I can get more info about this area is also fine. You don't need to spell out the answer, but if I have some ways on getting more knowledge on it, then that would be great.