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  1. K

    A few questions about solid-state relays

    Okay, good. I am essentially hoping to use a variable PWM and a low-pass filter as a variable DC voltage. Although, the board is also capable of digital output at +5V, +0V. Would it be sufficient to drive the relay using just a 178-ohm current-limiting resistor? In the picture, I did not...
  2. K

    A few questions about solid-state relays

    Thanks for the help; however, I don't think I completely understand. Specifically: I'm not sure what you mean by 'supply voltage'. Do you mean the control voltage? The SSR only has four pins, two for the control and two for the load connection. If you do mean the control voltage, I do plan...
  3. K

    A few questions about solid-state relays

    Today I bought a solid state relay, the datasheet for which can be found here. My goal is to use it to switch 120VAC, controlled by an Arduino Uno board (with Atmega 328 microcontroller). I am very rusty since my days in EE classes, and have not worked with solid state relays at all. In the...
  4. K

    Wireless energy transfer/able to power your own house?

    No, they didn't feel anything.
  5. K

    Wireless energy transfer/able to power your own house?

    If it was an active device, it had a battery. I actually used to work at Medtronic, and most of the more power-hungry devices would be charged inductively through the skin. Most of the time the patient would have to wear some sort of belt which plugged into a wall, 2-3 times per week. The...
  6. K

    Household wiring

    I'm not fixing a dang thing myself. I will, however, put pressure on my landlord to get it fixed :).
  7. K

    Household wiring

    I am curious as to how any of this could be changed in the breaker panel...wouldn't it require total rewiring to change which circuit the A/C is on? All of the circuit breakers are 15-amp. Is there any chance it would be safe to just put a 20-amp in place, or might the wiring not be fit for it?
  8. K

    Household wiring

    This is how the wiring is set up in the basement I am renting out: On one circuit, there is a jacuzzi and a pond pump, both which run 24/7. There is a porch light that is controlled by a light switch inside. It is set up such that in order to keep the pump and jacuzzi running, you have to...
  9. K

    Would like some advice becoming more employable for power industry

    Note: This is Physics Forums, not reddit :). I don't work in the power industry but I know many that do. The best advice I can give you is to get involved with your local IEEE PES (power and energy society). They have societies in almost every major city. Go to their meetings, volunteer to...
  10. K

    Suggest Calculator For Electrical Engineering

    Hey - that's good info. Sometime us old guys get stuck in our ways. Thanks for sharing.
  11. K

    Suggest Calculator For Electrical Engineering

    Yes. I haven't used it, but at least one gentleman on the internet recommends the former: http://www.techpoweredmath.com/review-ti-89-vs-ti-nspire-cas/" [Broken].
  12. K

    Suggest Calculator For Electrical Engineering

    TI-89. I can't recommend it enough. I graduated months ago and I still use it every day. The symbolic math (including complex math) is really great - and you can set it to output functions in a very readable format, like you'd write it on paper. You can easily store things in variables (both...
  13. K

    Peltier Cooling Heat Sink

    Yes, it is possible. I am assuming you will have some chamber with these vaccines. You will need to have a way to circulate the air in the cold chamber as well - think of it as a "cold sink". As far as the heatsink for the hot side, you NEED to specify how much heat you are dissipating, in...
  14. K

    How long will a lc tank circuit oscillate after power is removed?

    It will decay exponentially. Usually you specify the time it takes to reach a certain ratio of the maximum (usually 1/e or about 36%), since mathematically the amplitude of oscillations will never reach zero.
  15. K

    Moisture sensors - do they exist

    Sensors as components just sense things, they don't produce audible alerts (generally speaking). You would have to have some other circuitry to read the sensors and produce an alert.
  16. K

    Levels of difficulty in Electrical and Computer Engineering

    I actually have degrees in both electrical and computer engineering. For me (and for most in my school), electrical was the more difficult of the two. The difference was just a few classes: differential equations, electromagnetic theory, and discrete math. BUT, now that I have a job which...
  17. K

    How do i solve the following circuit?

    I am not sure what you are trying to do here. V1 and V2 are in parallel - they will always be the same. Putting voltage sources in parallel is a bad idea! The current through the resistor is simply V/R. Plugging in zeros for everything just makes the current undefined.
  18. K

    What amperage in this wire?

    I would use 6-gauge. If you don't know exactly how it works, better to play it safe. I've (re)wired cars before, and one thing I can tell you is that the material protecting it is just as important as the electrical ratings. It will likely have to endure water, high temperatures, bits of salt...
  19. K

    Need expert opinions

    Why was the link deleted? I am interested to see it.
  20. K

    Need a software for working on electrical machines

    Honestly, I have no idea what you are talking about or what you are asking for.
  21. K

    Switching/circuit breaker circuits

    Yes, 100 Khz should be very doable, but keep in mind there will be some finite switching time. Do you have any requirements regarding the "off" and "on" resistances of the switch? What about the amount of current going through? The simplest type of switch just uses a single MOSFET - when you...
  22. K

    Resistance between two points in an infinite volume of resistive gas

    Right. Except it would be a 3-dimensional network. So, how do I model that mathematically? I really don't know.
  23. K

    Resistance between two points in an infinite volume of resistive gas

    Imagine for a moment that there is a box filled with some resistive gas. You are holding two probes a distance of X units away from each other in the center of the box. There should be some finite resistance between the two probes. Now imagine that the box is infinitely large, so that the gas...
  24. K

    String of LEDs in parallel w/correct resistors and a TIP31 Transistor.

    It sounds like you are using the transistor as a switch. Think about how much current it would need to "turn on", and what the current requirements likely are of the sound cards. They may be intended to drive different things. What do you think the input impedance is of your LED circuit...
  25. K

    Where does lightning want to go?

    Keep in mind that there are charges flowing in that ionized column of air. They will dissipate chaotically throughout the ground as they interact with each other and the earth. It is certainly possible that some are dissipating through the grounding equipment. Its also possible that the...
  26. K

    Question about going into EE/CmpE

    The book carlgrace suggested is awesome. I used it as a supplement to my learning throughout my EE undergrad. My recommendation is, if you can afford it, to buy some hobby kits that provide a fun introduction to CE-type projects. They will help you not only learn new things, but get your head...
  27. K

    Homemade Transformer

    Not quite, you will get severe rippling without a capacitor to smooth it out. Rectifiers have some loss - the simplest type, a full-bridge rectifier, will have a loss equal the forward voltage of two diodes, or about 1.2-1.4V for PN junction diodes. You will need to design around this: the...
  28. K

    Looking for a switch

    Are you talking about a networking switch for ethernet networks? I ask because you said "output of the switch should be 12vdc", but an electrical switch does not have an output. A switch in the context of electronics is a device which makes or breaks electrical connections. What I'm getting...
  29. K

    Heart-shaped badge

    The 4017 doesn't have an option to "count down". You will have to add some components to do it. You could wire each LED in a CW and CCW direction, and use 8 switches to control it. This could be as simple as using a multiplexer-type device to switch between the CW/CCW wiring schemes.
  30. K

    Help: Diode doesn't behave as it should when connected to coil

    I'll second this. This may be your DMM's way of telling you to change the scale.
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