A smaller capacitance cap that is charged to a high voltage can kill you. = Melting a dime is impressive but not nearly that amount of energy is requir= ed to stop your heart. Current is like how much a baseball bat weighs. Voltage is like how fast i= t is swung. And of course it matters what the bat hits. Tap your heart di= rectly and it may stop. Give your leg a great whack and your heart may not= care. USB oscopes are not automatically toys. A USB scope can be quite good. Sm= all electronic devices may be quite wonderful and large devices may be heav= y boat-anchors. First glance may not tell the tale. A battery is just another bathtub full of electrons ready to go. There is = no way to tell ( at least in a short moment ) if a mystery box supplying el= ectrons is using a capacitor , a chemically driven battery , a generator , = or a cat on a hot tin roof. Oh I wish someone who knew the ins and outs of electronics could sit with y= ou when you are doing your experiments. It really, really helps to visuali= ze electrons as though they are flowing through wires the same way water pa= rticles flow through a pipe. Increase the voltage/pressure and you increas= e the number of electrons/water particles that flow through the pipe each s= econd. That rate of flow for electrons is amperage. It is very good that you speak what you believe you have heard people expla= in and what you have observed with experimentation. It gives PIClisters a = chance to comment on your grasp of the concepts. There are a lot of people= who like to help when they have a tidbit to offer. gus in denver =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D On Nov 26, 2013, at 12:32 AM, Lindy Mayfield wrote: Thanks to everyone for helping me so far. I've read and tried to understan= d each post, and Google the bits I didn't understand. That graph was great= .. I was trying to make a similar one with excel but failed. I don't completely understand volts and current, but I now have a semi-work= ing knowledge of V/R=3DI. And I think I know enough to work with it. Arme= d with help from this group and google, watching youtube videos with exampl= es, often using an oscilloscope, have helped me enormously. (I am saving m= oney for a proper one, not the cheap USB one.) One thing I've learned is that batteries are "different." I don't remember= the details, but they don't fit into my imaginary images of how electricit= y works. A large, charged capacitor in fact does fit my understanding. (A big one r= eally can kill. I saw a demo of what one can do on youtube. It melted a d= ime.) Another thing I've learned a bit more is why a circuit is built the way it = is. Not only do you work with individual parts, resistors, capacitors, tra= nsistors, etc, but also with blocks of parts. For example, on a youtube vi= deo he showed on the oscilloscope a noisy DC input current. Then he put in= a capacitor and I could see how it got smooth. And resistors and capacito= rs in a certain way do specific things. Diodes in certain configurations, = and so on. In one place I learned that two resistors in the right place wo= uld convert a +5v to +3v for a Raspberry Pi. I assume that in this particu= lar case a voltage regulator was a bit overkill. Motors pose unique problems, which I saw on an oscilloscope, so you guys kn= ow just to put these pieces here and there, and it fixes it. I thought that learning all about each component was all I needed (like in = the beginning electronics books, Forrest Mimms is my favorite.) Wrong. I've observed a lot with the bench power supply. On simple DC motors, incr= easing the voltage increases the speed, while increasing the amps increases= how powerful it is. That makes sense. But on the other hand, on a more complex motor, the bench power supply woul= dn't go over 5 volts, no matter where the dial was. But increasing the am= ps increased speed. That was a bit weird. Now the simple math makes more sense when I understand how the parts work t= ogether. I could calculate how big a resistor to use with an LED, but I th= ink that 220K is about normal. Someone gave me a raspberry pi which is why I'm getting into this again. I= t's quite fun trying to control things using Linux rather than PIC assemble= r. Thanks again. Lindy --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .