I recently found 2 power supplies possibly sufficient for the Arduino Uno - AKA 5 volts, with 1-1.1 amperage: AKA 1A. Reasonable amperage for the Arduino Uno is 40-50 mili-amps. AKA 40-50mA.
…in short, both supplies are 5v x: #1 is 1A, #2 is 1.1A
So, WAY WAY WAY WAY more amperage than the Arduino is designed for; many many times over. Could it ruin the board? I know amperage kills people, typically not volts.
From what I know, resistors lower the volts, which is basically the pressure of the electricity, but not the actual motion of the electrons; just how many can move @ what density.
500,000 volts of current moving through the body will immobilize a person… @ the mili-amperage, or micro-amperage range, depending on how many zeros you want to use.
50 volts @ 50 amperage to a grounded person and they are toast.
…but I don’t know about the actual current as it applies to circuits. From what I know, current is how fast the volts are moving through the circuit. Is the human body a circuit? I think it logically so to assume. So… I’d probably destroy my Arduino, and I don’t wanna learn this $35 lesson if I can just ask y’all.
mili-amps vs amps are a factor of three I believe. That’s a big change.
Basically, I’m asking 2 questions:
how do I step down the current on these power supplies (…not the volts), so that I can use them for my projects?
Can I hook up the Power Supplies’ |+| & |-| on the bread board, use the breadboard to connect the equipment to step down the amps, and then connect more jumper wires directly into the Arduino? (AKA the 5v and GND pins?)
If needed, I can supply pics if people do not understand what I’m saying, and/or provide schematics.
You don’t need anything. A device won’t draw more current than it needs if the voltage is correct. Think of plugging in a lamp to a wall outlet. The outlet can provide 15 Amps at 120 VAC but the lamp will only draw what it needs (1/2 A for a 60 W bulb for example).
Yes, the body is a complex circuit and has a value called impedance. At DC, your body is a high value resistor (mega ohms) which is why you don’t get burned by touching the terminals of the car battery (OK, unless you’re really wet). At AC, however, your body looks like a much smaller resistor and if the voltage is high enough (less than 100 VAC), it only takes a few mA to kill you (the AC interferes with the electrical system of your heart, whereas with DC your body just becomes a big resistor and you get burns instead).
The current rating on the power supply is what it can deliver, before the voltage starts to sag/sink/collapse. How much current it regulates is dependant on the resistance of the load. Which for microcontroller/digital circuitry is usually very dynamic due to the switching of it’s internals. But also fairly high on average.
Your Arduino, or microcontroler circuit won’t draw that much current unless you have a short circuit in it. Or perhaps big electric motors/stepper motors fed by it.
Dave Mueller:
You don’t need anything. A device won’t draw more current than it needs if the voltage is correct. Think of plugging in a lamp to a wall outlet. The outlet can provide 15 Amps at 120 VAC but the lamp will only draw what it needs (1/2 A for a 60 W bulb for example)
I thought that was due to a system of electrical devices within the lamp that provided for the ideal current and volatge to pass through it.
Dave Mueller:
.
Yes, the body is a complex circuit and has a value called impedance. At DC, your body is a high value resistor (mega ohms) which is why you don’t get burned by touching the terminals of the car battery (OK, unless you’re really wet). At AC, however, your body looks like a much smaller resistor and if the voltage is high enough ([sic]less than 100 VAC), it only takes a few mA to kill you (the AC interferes with the electrical system of your heart, whereas with DC your body just becomes a big resistor and you get burns instead).
That’s very interesting. Why is this?
I know this is a bit off topic, but I am curious as to why this is.
I know that A/C current has to do with the sine wave, and that it cycles like any sine wave. The math for A/C is quite complex, but from a conceptual standpoint, I think I understand A/C better than D/C, but really I don’t understand either very well.
Also, I think it would be good to learn how to step down current… at the same time, if I’m not mistaken I believe that current and volts are inversely related, @ least in A/C, so that if you lower the voltage, you up the current. Is this accurate?
Sisyphus:
I thought that was due to a system of electrical devices within the lamp that provided for the ideal current and volatge to pass through it.
An incandescent bulb is just a resistor. When enough current flows through the filament, it gets hot enough to glow. The simplest practical application of Ohm’s law (look it up).
Dave Mueller:
Yes, the body is a complex circuit and has a value called impedance.
Sisyphus:
That’s very interesting. Why is this?
You need to study linear versus non-linear elements and understand impedance.
Sisyphus:
Also, I think it would be good to learn how to step down current… at the same time, if I’m not mistaken I believe that current and volts are inversely related, @ least in A/C, so that if you lower the voltage, you up the current. Is this accurate?
You can’t really step down current like you are thinking. For DC, voltage, current and resistance are related by Ohm’s law V = I x R.
For AC, Ohm’s law still applies IF the only components are resistors. Once you add capacitors and inductors, then you have to learn about impedance.
Sorry I haven’t been around to post on this topic in a while.
I will read up on the links provided after this post.
First off, thank you for the input. I will learn about impedance.
Also, what I was curious about doing, was hooking up the positive and negative wires of a power supply to a breadboard, and using pieces of jumper wire to plug into the Arduino Uno @ the 5v and ground locations.
…it seemed to me, if I were to do that, the amperage and voltage would need to be spot on.
It depends on what sort of power supply it is. If it is an unregulated supply (like just a transformer, a bridge-rectifier, and a buffer capacitor) then the voltage might actually be higherthan the states 5 volt. It will keep the voltage up at atleast 5 volt upto the stated current drain. Pulling more current makes the voltage drop. Drawing not so much current would letthe voltage rise above the stated level. There should be a symbol on the device to indicate what sort of regulator it is. But I don’t have a link ready at the moment to show examples and clarify.
Sisyphus:
Also, what I was curious about doing, was hooking up the positive and negative wires of a power supply to a breadboard, and using pieces of jumper wire to plug into the Arduino Uno @ the 5v and ground locations.
…it seemed to me, if I were to do that, the amperage and voltage would need to be spot on.
Doing the above would be a bad idea. The Uno has a voltage regulator which takes a range of input voltages and tries to make an output voltage = 5V from the input, despite whatever current is drawn. Connect another voltage regulator to that output voltage and one of the regulators may overheat, as it's very unlikely both voltages will be "spot on".