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Discussion in 'General Electronics Discussion' started by Electro132, Feb 17, 2013.

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  1. Electro132

    Electro132

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    Feb 12, 2013
    Hi,

    Could resonance be picked up by a receiver? and if so by what?
     
  2. john monks

    john monks

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    Mar 9, 2012
    Receivers pick up a change of an electric field. This is done in automobile receivers. The body picks up one have of the changing electric field and the car ariel picks up the other other half or what is called the opposite polarity or phase.
    Receivers pick up a relativistic affect of the change of a changing electric field what is called a magnetic affect. This has been described by great physicist such as Albert Einstein.
    So a more direct answer to your question is that a receiver picks up the effects of resonance in the form of electrostatic radiation, such as in a car radio or electromagnetic radiation such as in a little battery operated radio.
     
  3. dietermoreno

    dietermoreno

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    Dec 30, 2012
    Resonance better be able to be picked up by a receiver, or else I'm not sure how you are viewing this web page on your computer since your computer modem uses tuned circuits as well as the internet network uses tuned circuits.


    Are you sure that's what you really mean?

    Perhaps are you asking something less literal?

    Like are you trying to ask if your guitar amp can receive modulated carrier waves?

    The answer to that is yes. Yes your guitar amp can receive modulated carrier waves, but that is because there is dirt on the cables that is demodulating the carrier waves and the guitar amp is only amplifying the audio of the demodulated waves. The guitar amp shouldn't be demodulating the carrier waves if there is no dirt on the cables. If the guitar amp had no dirt on the cables then technically it could amplify radio frequency (RF), but you would not be able to hear the demodulated audio frequency (AF) because there is no dirt to demodulate the carrier waves, but technically you could put a crystal detector connected to a guitar amp with no dirt on the cables and then that would amplify RF before the crystal demodulates into AF. The only problem is that nothing is ever perfect so I always have dirt on my cables. To not have dirt on your cables to build a RF amplifier, that probably means sodering instead of using instrument cables.
     
  4. Electro132

    Electro132

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    Feb 12, 2013

    I need some assistance in converting 13 - 60 pulses per second, 7 - 13 pulses per second, 4 - 7 pulses and 1 - 4 pulses per second to Hz.

    I also need to know how does resonant frequency change on a tuned circuit (what components would i need to achieve these pulses/hz) by providing feedback onto it and changing the resistor.

    I'm guessing the end part would be the sine, triangle, sawtooth waves that get emitted by light? :)
     
  5. john monks

    john monks

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    Mar 9, 2012
    Hertz is the SI (international system of units) unit for cycles per second.
    For example 4 cycles per second is 4 hertz (Hz).

    A sine wave contains only one frequency.
    A triangle wave contains odd harmonics.
    A sawtooth wave contains even and odd harmonics.
    It could be that everything is comprised of sine waves but I don't know for sure.
    I can tell you that anything other than a sine wave contains more than one frequency.
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    That's easy, just write the number followed by Hz. E.g: 13 pulses per second = 13 Hz.

    Fun aside:
    Convert to what? Pulses per second is the same as Hertz (Hz). Do you really mean convert?

    That depends entirely on the circuit. There are many types of resonant circuit and each can be tuned in one or more ways.

    This sounds more like you want to build a frequency generator for low frequencies, do you?

    You need to be much more specific if you want to get useable answers. Tell us exactly what you need:
    - your application. This is the most important part helping us understand what you want to do. Sometimes what you want to do and how you want to it is not the best way to achieve the final goal.

    Also:
    - voltage levels,
    - current levels
    - frequency range(s)
    - signal form(s) (sinusoidal, rectangular, triangular...)
    - anything else that comes to mind (e.g. does the generator have to run synchronously to another generator, do you need a trigger siganl etc.)
     
  7. BobK

    BobK

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    Jan 5, 2010
    Resonance is not going to have much to do with pulses at the rates you are talking about. Yes, you could build resonant circuits for those low frequencies but it would take them minutes to settle when a signal was received.

    If you want help, stop asking questions that don't make any sense and tell us what it is you are trying to do.

    Bob
     
  8. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    Sorry for the questions guys, just trying to get my head around it, that's all.

    Ok basically here's what i want to build. I am looking to have an inverter connected to 3V power source which is connected somehow to 3 different oscillators (audio 16hz - 20khz, RF 100 khz - 100 ghz & LFO under 20hz) in resistors and capacitors (or if there are much more better and simple components) using a switch which are then amplified and controlled by a VCO and projected out using one of the waveforms (not sure if it's an antenna or emitter used for best method). :)
     
  9. Harald Kapp

    Harald Kapp Moderator Moderator

    11,453
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    Nov 17, 2011
    For these frequency ranges you'll need a few different oscillators /generators.
    16 Hz - 20 kHz can be done with one circuit.
    100kHz - 100GHz is in my opinion impossible with one generator. You may need probably 2 generators to achieve this range.
    LFO 20Hz is covered by the first oscillator.

    And I still don't get what the inverter has to do with this. Could you supply a schematic clarifying your intentions?
     
  10. dietermoreno

    dietermoreno

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    0
    Dec 30, 2012

    (1)
    13 pulses/second =13 cycles/second =13 Hz

    (2)
    The resonant frequency in a circuit consisting of a capacitor and an inductor (LC circuit) is:

    f = 1 / ( 2 pi *(square root of (L*C)) )

    , where L is the inductance in henries, C is the capacitance in farads, and f is the frequency in cycles per second (or otherwise known as hertz).

    http://en.wikipedia.org/wiki/LC_circuit


    The resonant frequency in a circuit consisting of a capacitor and a resistor (RC circuit) is:

    f = 1 / ( 2 pi*R*C )

    , where R is the resistance in ohms, C is the capacitance in farads, and f is the frequency in cycles per second (or otherwise known as hertz).

    http://en.wikipedia.org/wiki/RC_circuit


    These are idealized equations. There is usually inductance, capacitance, and impedence at the same time. Impedence is the DC equivalent of resistance. Impedence is the sum of inductive reactance, capacitative reactance, and resistive reactance.

    Making a kink in your garden hose slows down the flow of water out of your garden hose.

    Coiling your garden hose also slows down the flow of water out of your garden hose more than if it were straight.

    Coil with water flowing through it creates a force that impedes the flow of water, in electric circuit the coil with electric current flowing through it creates a force that impedes the flow of electric current.


    The LCR circuit is ignoring impedence. The LCR circuit is assuming all impedence is the DC equivalent to the resistive reactance of the resistor in the circuit. The LCR circuit is the same thing as the LC circuit but with a resistor in it. The resistor in the LCR circuit attenuates the signal before the LC circuit, or in between the inductor and the capacitor, or before the inductor, or before the capacitor. The position of the resistor in the LCR circuit makes the bidirectional LC circuit into a directional circuit. Now order of input and output matters. The resistor slows down the change that either the inductor or the capacitor can do on the circuit, or the resistor slows down the change for both inductor and capacitor. This rate of change is the frequency. The capacitor is less similar to the inductor than the inductor is to the resistor. The capacitor creates frequency by discharing electric current when it is full of current. The inductor always has electric current passing through it like the resistor. Inductive reactance of the inductor makes the inductor behave like a resistor, but also a little bit different a resistor does not generate a magnetic field and as electric current passes through an inductor it generates a magnetic field. In an LC circuit, the capacitor rapidly breaks the magnetic field generated by the inductor, generating frequency of an electromagnetic wave.

    The oscillating electric field of the capacitor discharging intersects with the oscillating magnetic field of the inductor. The magnetic field of the inductor is oscillating because it is only generating a magnetic field when current passes through the coil.

    The difference between an alternating electric current and an electromagnetic wave is that an alternating electric current is only the electric field polarity alternating, while an electromagnetic wave has both the electric field polarity alternating AND the magnetic field polarity alternating.

    The electric wave is perpendicular to the magnetic wave, to create the electromagnetic wave.

    http://science.hq.nasa.gov/kids/imagers/ems/waves2.html

    http://missionscience.nasa.gov/ems/02_anatomy.html

    http://en.wikipedia.org/wiki/Electromagnetic_radiation

    http://en.wikipedia.org/wiki/Electromagnetic_spectrum

    The resonant frequency for an LCR circuit is:

    f = square root of ( ( 1/ (L*C)) - (R/L) squared )

    , where L is inductance in henries, C is capacitance in farads, and R is the resistive reactance of the resistor in the circuit in ohms.

    http://en.wikipedia.org/wiki/RLC_circuit

    Remember that where you put your resistor in your RLC circuit does matter.

    The low pass filter puts the resistor before the capacitor. The low pass filter puts the resistor connected to the hot wire (you know why the power lines outside your house have 3 wires in one direction but only one wire in the other direction connected to the ground, don't you...or if not read here...http://en.wikipedia.org/wiki/Ground_(electricity)), and the low pass filter puts the ground across the output of the capacitor and input of the capacitor is put across the output of the circuit.
    http://en.wikipedia.org/wiki/Low_pass_filter

    The high pass filter puts the resistor after the capacitor. The high pass filter puts the resistor connected to a tap from the hot wire to the ground wire. The tap to ground is connected to the output of the capacitor and connected to the output of the circuit.
    http://en.wikipedia.org/wiki/High_pass_filter

    So you see in those links that the low pass filter and the high pass filter are actually realized as RC circuits, not RLC circuits.

    The circuit could also be RL (which is actually RLC from parasitic capacitance using the Earth as the terminal of a capacitor). When I turn the volume knob on my guitar, the volume knob is a potentiometer (pot) that increases resistance or decreases resistance. Increasing the resistance modifies the capacitance, thus creating a condition of a resonant circuit. When I turn the volume knob of my poorly grounded shitty guitar on my poorly grounded shitty guitar amp, parisitic capacitance from the Earth and the inductance of the pickups create an LC circuit and since resistance modifies the capcitance that enters the circuit from the Earth, when I turn the volume knob on my guitar I can tune to AM radio stations. Note that log pots are used for volume since human hearing is logarithmic. Note that linear pots are used for tone control. Note that the transistors in the guitar amp can act as an envelope detector to demodulate the radio waves. Semi conductors only allow current to flow in one way. A transistor is composed of two different types of semi conductors. With low frequency signals, diodes and transistors will convert from AC to DC. At radio frequency signals, diodes and transistors will convert from an alternating radio wave to an envelope of the alternating radio wave (I'm not sure if I got that right, someone please correct me if I'm wrong). Diodes and transistors are frequency dependent devices. Of course you want to make your circuit active and add in amplification. The crystal radio reciever uses no amplification. So you want to add in amplification. The super heterodyne receiver is more efficient than the crystal reciever amplified since it steps down the frequency to a frequency that the RF amplifier can handle to accurately amplify to a high gain at low noise.

    http://en.wikipedia.org/wiki/RLC_circuit

    http://en.wikipedia.org/wiki/Potentiometer

    http://en.wikipedia.org/wiki/Guitar_wiring

    http://en.wikipedia.org/wiki/Potentiometer#Logarithmic_potentiometer

    http://en.wikipedia.org/wiki/Potentiometer#Linear_taper_potentiometer


    http://en.wikipedia.org/wiki/Transistor

    http://en.wikipedia.org/wiki/Diode

    http://en.wikipedia.org/wiki/Semiconductor

    http://en.wikipedia.org/wiki/Frequency_response

    http://en.wikipedia.org/wiki/Cat's_whisker

    http://en.wikipedia.org/wiki/Detector_(radio)

    http://en.wikipedia.org/wiki/Envelope_detector

    http://en.wikipedia.org/wiki/Crystal_radio

    http://en.wikipedia.org/wiki/Super_Heterodyne_receiver





    Now I think you might be ready to start experimenting.

    Now what is it that you wanted to build, after I just explained to you what you can do with a resistor in a circuit to created a tuned circuit?

    You want to do something with an inverter providing power for the tuned circuit?

    NO. No you don't. An inverter converts DC to 60Hz AC. If you use an inverter the frequency of your circuit is 60Hz.


    P.S.:

    (3) Radio frequency used to broadcast radio waves is not in the visible spectrum, but the visible spectrum is part of the electromagnetic spectrum. Go to the Wiki link I posted for electromagnetic spectrum.
     
  11. BobK

    BobK

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    Jan 5, 2010
    Once again you have not told us what you want to do. You have told us what you think you need (and your statements here are confusing at best). Tell us what you are trying to achieve, not that you need an oscillator in the range of 100KHz to 100GHz (which you surely will not be able to build). What are you going to do with this oscillator?

    Bob
     
    Last edited: Feb 21, 2013
  12. Electro132

    Electro132

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    3
    Feb 12, 2013
    So which resistors and capacitors are best to go with these frequencies?

    16 Hz - 20 kHz can be done with one circuit.
    100kHz - 100GHz is in my opinion impossible with one generator. You may need probably 2 generators to achieve this range.
    LFO 20Hz is covered by the first oscillator.

    I've tried to get my head around it but for some reason i get something like 0.345698...etc. as the answer. For an example, I chose the resistor 110 ohms and Capacitance of about 0.22 farads but got the answer above. Would like to also know if i did the equations you mentioned, is the answer in Hz?
     
  13. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    I want to build a Resonator which can be used for my experiment in examining the power of vibrating waves.

    It should have an Audio, RF and LFO altogether and have the ability to be powered by an inverter which can provide power to a supercapacitor and thus the supercap will then send power to the rest of the circuit.

    Finally the tone will be used by a linear pot for the audio, RF and LFO to be connected to it whilst having Log Pots to control volume. This should all come out on either a sine wave or non sine wave which ever is more effective.

    Was thinking a Phase shift Oscillator was better for this but having difficulty building the schematics for it. Any help is appreciated.

    Just a reminder i will use it in an experiment where i examine the power of vibration through several walls of glass, concrete and other materials.

    Cheers
     
  14. davenn

    davenn Moderator

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    Sep 5, 2009
    All your responses are still quite confusing
    mainly because of the terms you are using that are either totally incorrect or at least not quite right.....


    Do you really mean oscillator ?

    As BobK has already told you the LF oscillator and audio oscillator are covered in the once oscillator.
    The 100kHz to 100GHz is pointless for looking at resonance response in glass and walls etc .... you are not likely to measure anything anyway you would need multiple oscillators to cover that range and from 10 GHz to 100 GHz the difficulty is high and expensive and the lack of knowledge you have so far shown ... indicates its very far beyond your abilities

    Buy a function generator that goes from 10Hz or so up to ~ 20kHz
    That freq range is going to give you the most info for the materials you are looking at and feed its output to a decent quality amplifier

    Now all that is just the sender side .... then you need to look at the receiver side
    vibration detectors that can mount on the materials of interest, preamplifier circuits and output to a computer via an A to D system

    All in All it really sound a long way above your skill level :(

    Dave
     
    Last edited: Feb 27, 2013
  15. Electro132

    Electro132

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    3
    Feb 12, 2013
    Hey i'm trying to find out about how to make a Linear Pot move between 3 different Frequencies. So far i found out that 6.5 henries with 0.47 microf's are equal to about 0.57hz and 6.5 H with 0.001 = 12.40hz. If i apply this would it mean that the linear pot starts off from 0.57hz in a LC circuit? OR which circuit is best for this type of thing?
     
  16. davenn

    davenn Moderator

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    linear pot = a variable resistor ... it isnt going to move between any set of frequencies

    what do you really mean ?

    we are all trying desparately to help you, but your descriptions are making it really difficult :(

    Dave
     
    Last edited: Feb 27, 2013
  17. dietermoreno

    dietermoreno

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    Dec 30, 2012
    I beg to differ that a pot in a circuit with a capacitor can indeed create a tuned circuit, at least that appears to be what happens with my guitar that has RF interference problems when I turn the tone control knobs (linear pot) it doesn't do anything but when I turn the volume knob (log pot) I can tune to different AM stations. At one volume level there is a news station at 780KHZ and at the opposite volume level there is a gospel music station at I think around 1200KHZ (that is what I found on the internet for gospel music stations nearby me). The news station transmitter is 15 miles away from my house and the gospel music station transmitter is 10 miles away from my house. Also I was using the pickup selector switch at the same time to create taps to the total number of coils in the circuit.

    So a linear pot can not create a tuned circuit but a log pot can create a tuned circuit? Or at least if appears that a log pot with guitar pickups can create a crude tuned circuit for AM stations transmitting at thousands of watts only a few miles away. I think the frequency equation is logarithmic/exponential behavior, so that is why a log pot will work but a linear pot will synthesize such low frequencies that it doesn't do anything?

    Or is it likely that the log pot doing anything was just dumb luck and it only worked because I was using the pickup selector switch at the same time?
     
    Last edited: Feb 28, 2013
  18. duke37

    duke37

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    Jan 9, 2011
    An audio amplifier will only respond to RF signals if it is not working properly. It is anybody's guess how any particular amplifier does this.

    Some audio signal generators use a Wien bridge oscillator which can be tuned with a pair of ganged resistors or capacitors. A frequency range of about 3:1 is common.

    If you wish to use a voltage source and get a wider range then I would suggest two oscillators, one of which is tuned with a voltage controlled varactor. The two signals are then mixed and passed through a low pass filter to give the output. An output of 0 to 100kHz may be possible. This principle is used in a theramin (Doctor Who)

    I believe there are voltage controlled filters which could be used to make an oscillator.
     
    Last edited: Feb 28, 2013
  19. davenn

    davenn Moderator

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    you have a lot of misunderstandings in there ... just as in your original posts on your guitar and amplifier problems picking up RF

    so I stand by what I said earlier

    Dave
     
    Last edited: Mar 1, 2013
  20. Electro132

    Electro132

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    3
    Feb 12, 2013

    Ok, well this is what i have in mind:

    - the power source comes in
    - A knob is connected which can be turned clockwise and anti clockwise to choose from a set of Frequencies. E.g. Starts from 0.57hz and ends at 500 mhz (or more)
    - the chosen Frequencies then come out of the output and into an amplifier which boosts it. This also has a knob (most likely a Log Pot for volume)
    - It then gets amplified some more by a Darlington pair (or is this more suited before the amplifier?)
    - It finally goes out of an Antenna

    Still trying to do the first part (pondering whether its a linear pot or log pot, how the oscillator circuit goes, and so on...etc
     
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