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    10X Multiplier-Prescaler for Frequencies Above 3GHz

    Does anyone know where I can purchase a 10X multiplier-prescaler for my R&S 3GHz spectrum analyzer? This is not for accurate quantitative readings but rather as a simple detector of the presence of RF signals up to 30GHz. I am hoping to spend less than $500. Maybe that puts it in the "kit"...
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    Circuitry to Randomize Audio Test Signal

    Can you recommend an inexpensive multiplier IC for this application that will operate on single supply? Being very expensive here, I twice I ordered an AD633 from China and they were both fakes. I also looked into a single Gilbert cell. It looked simple, but I suspect getting it to work...
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    Circuitry to Randomize Audio Test Signal

    How about linear mixing with a recorded low frequency sound that is non-repetitive? Maybe something from nature, with low pass filtering to bring it beneath 120Hz. That would modulate the amplitude. Is there any way this same approach can be used to also modulate phase and /or frequency? I am...
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    Circuitry to Randomize Audio Test Signal

    I have line level 120Hz sine wave that I want to randomize (not evenly modulate) in amplitude, frequency and/or phase by a factor of about 5-10%. Stated another way, I want to simulate a signal that is slightly unstable in as many ways as are practical, but still essentially a 100Hz...
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    Oscilloscope Probe at Audio Amplifier Output Causes HF Oscillation

    Asked the wrong question and got the right answer. Made my day. I connected a 104 ceramic across the amp's output pins. Problem solved. I should mention there was a 10K resistor also in parallel, not shown on the previously attached circuit.
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    Oscilloscope Probe at Audio Amplifier Output Causes HF Oscillation

    I built a John Hood 1969 type, single ended audio amplifier. It works fine into a speaker. But when I connect my Atten digital oscilloscope across the output, a 2Vpp 5MHz sine wave appears on the screen. It does not affect the audible sound quality. I tried swapping probes, channels, etc. to no...
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    Amplitude Modulation Using Op Amp Inputs

    Yes, you are correct about the 2N3819 pinout. I misunderstood from an earlier reply that a JFET was the way to go. At the time, I also ordered an AD633 four quad mixer IC. They are not cheap, but I am now thinking that is the least challenging option for the type of output I am seeking. Here...
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    Amplitude Modulation Using Op Amp Inputs

    I refer to the diagrams in my first and second posts above. The FET I ordered finally arrived by post. It is a Fairchild 2N3819. The pinout is given as D G S when viewed from the front. As shown in second post diagram, I fed the ELF sine wave 2Vpp into the gate and connected the drain to pin 3...
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    Amplitude Modulation Using Op Amp Inputs

    Yes. But junction noise is not what I want. Anyway, that part of the circuit is fine. To use the ELF as the carrier, it seems I will need an additional op amp, with a JFET, after the noise stage to function as the modulator. The noise will be low pass filtered (not shown on my original diagram)...
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    Amplitude Modulation Using Op Amp Inputs

    I did not see a resolution or working schematic in that discussion. Is the solution as simple as feeding the ELF through a JFET into pin 3 of the TLC272 with no other added parts? I would try now, but do not have a JFET on hand. But my intent is to modulate the ELF with the capacitive noise...
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    Amplitude Modulation Using Op Amp Inputs

    The circuit below, once completed, is intended to modulate amplified noise from a 470uF cap with a CMOS generated ELF sine wave. As you can see, I am looking for a place to feed the ELF into the TLC272 stage to perform the AM function. Is this possible? If not, what is the simplest way of...
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    Can Batteries Exhibit Resonance at Particular Frequencies?

    By "resonance" I meant that the particular cell or battery might have some detectable non-linear response to the frequency of the pulsed DC. This might then be used to optimize the charging process. I guess it's a bench project then.
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    Can Batteries Exhibit Resonance at Particular Frequencies?

    If there was any experimentally determined advantage of a particular frequency, in terms of electro-chemical response or other phenomena, pulsed DC could be applied.
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    Can Batteries Exhibit Resonance at Particular Frequencies?

    I believe you are referring to eigenfrequency as opposed to electrical resonance. The latter may have implications with regard to battery charging efficiency?
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    Can Batteries Exhibit Resonance at Particular Frequencies?

    For example, if I connect an alkaline D cell across a signal source, could one or more resonant "peaks" be detected upon an oscilloscope? If so, what would be the best test set up to demonstrate this effect on a fully charged cell? If such resonance does exist, what is its cause and how...
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    Experiments with Three-Plate "Capacitors". Center Plate Being a Coil

    Electrical potential between the plates changes in distribution and polarity according to phase. Net amplitude remains constant, but depending upon the circuit, distribution is not necessarily even or balanced given that three charged "surfaces" are involved.
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    Experiments with Three-Plate "Capacitors". Center Plate Being a Coil

    Thank you for your comments. What I am investigating is possible interaction between the coil and plates as you correctly surmise. I do not have any suitable modelling software, but once I get a few opinions to help guide me I will bench test various frequencies and voltages. The general idea...
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    Experiments with Three-Plate "Capacitors". Center Plate Being a Coil

    I would like to understand the electrodynamics of each of the four configurations in my OP. I am retired now and this is just a learning exercise for me. By "polarity" I was referring to the magnetic field surrounding the coil. Thank you for your interest.
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    Experiments with Three-Plate "Capacitors". Center Plate Being a Coil

    Thank you for asking. Yes, it is a pancake coil wired as you describe, or the other way around. I am not sure if the polarity matters in terms of interaction with the two cap plates. According to my thinking, the resistor in diagram B would be on the "low" side so the coil always remains...
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    Experiments with Three-Plate "Capacitors". Center Plate Being a Coil

    I am investigating the interaction between capacitors and coils arranged in a stack. The configurations I intend to try are illustrated in the diagram below. There is an assumption that the input is bipolar, as if from the push-pull amplifier. The signal is any audio sine wave. Dielectric not...
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