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  1. M

    Impossible Op-Amp Circuit....Maybe

    Where the DC content comes from that requires DC feedback path, for starters? If there is no DC input, why is DC path needed?
  2. M

    Most power efficient display of single digits and color flap

    For LCD you can buy 7 LCD segments and place them in the correct geometry to save cost on the glass area (you pay by the overall area) Have you looked into Vacuum florescent displays?
  3. M

    How to test a Bi-Directional Triode Thyristor

    I'm glad for you, but that's the way it works. Did you read the white paper? I know it's a bit short on hard technical details (to say the least), but that's essentially what it is saying. BTW, the waveform in Jim's post is Voltage. A standard transformer conducts into the filter caps at the...
  4. M

    How to test a Bi-Directional Triode Thyristor

    At any point in time the triac can turn on and the transformer field (current) builds up. When the triac opens, the field collapses causing a voltage surge in the secondary which is captured by the filter capacitors.
  5. M

    Most power efficient display of single digits and color flap

    http://www.flipdots.com/electromagnetic-large-7-segment-display.html#.Vwa41XolloE [Broken]
  6. M

    Number of bits it takes to represent a number

    There are two subjects being discussed, and confused. 1. How many bits to represent a quantity of symbols 2. How to code numbers in binary. Maybe my wording is not precise, but how many symbols one might use, and what people decide the symbols represent are, for the most part, orthogonal...
  7. M

    Impossible Op-Amp Circuit....Maybe

    Can you explain why? ( in the context of a perfect amplifier with infinite input impedance, infinite gain, 0 offset, etc.)
  8. M

    Most power efficient display of single digits and color flap

    I agree Your lowest power all electrical solution will probably be an LCD display with an LED side light. (I have not done the power analysis) For example, http://www.good-display.com/products_detail/&productId=141.html Microcontroller families generally have devices with LCD drivers...
  9. M

    Impossible Op-Amp Circuit....Maybe

    Can you explain why in the context of a perfect amplifier with infinite input impedance, infinite gain, 0 offset, etc.
  10. M

    Impossible Op-Amp Circuit....Maybe

    I misspoke, kinda. They are ideal differential voltage sources, not "real" opamps. No output impedence, no bias current, no offset, infinite gain, etc etc. Actually, using real models would solve his problem since those node would not be floating. Ironically that would change performance by...
  11. M

    Impossible Op-Amp Circuit....Maybe

    They are not opamps. They are ideal circuit elements, so there is no such thing as bias current. Problem is that pspice will not simulate with floating nodes. For pspice, you need to add 100MegOhm resistors to ground on the floating nodes, other wise it can't find a quiescent solution to...
  12. M

    Why Do we ground an electronic circuit?

    Ground as an input is no issue to me. I'm referring specifically to this: "This is because GND is supposed to indicate zero volts, but an op amp never puts out exactly zero volts, making the original label confusing" What is he trying to say? It's also wrong because op-amps put out exactly...
  13. M

    Impossible Op-Amp Circuit....Maybe

    The 5 from the opamp to gnd is useless since OUT is 0 impedance. There needs to be a resistance fron the center node to ground or spice won't converge (possibly PSPICE puts it there automagically. Try 100MegOhms tp ground. No idea what "does not work" means. What was it supposed to do?
  14. M

    Why Do we ground an electronic circuit?

    That doesn't make sense? What opamp ever had an output pin labeled ground?
  15. M

    How do inductors store energy as a magnetic field?

    Let's say you are passing 1 amp through an inductor with a parallel 1 ohm resistor and remove the supply. The inductor has a magnetic field, and wants to maintain the 1 amp flow, so it will then create 1 volt to "send" the 1 amp through the 1 ohm resistor, reducing the magnetic field as it...
  16. M

    Transistor Logic Gate : NOT Gate Explanation?

    One design flaw in this weird circuit is that Q5 can turn itself on through collector-base leakage. Needs a resistor from base to ground. Other than that, it looks like it was designed by one of those genetic evolution circuit generator programs...
  17. M

    How to test a Bi-Directional Triode Thyristor

    @Planobilly I really wish you could have made the simple measurements I suggested. That would have helped locate the issue. Who knows how much has been damaged now. BTW, starting with low line voltage is a good way to destroy things. Eventually you will need to make the measurements I...
  18. M

    How to test a Bi-Directional Triode Thyristor

    Just want to share an insight (from the white paper) about why this is a "magnetic" power supply, and can have a significantly smaller transformer and output caps compared to conventional supplies. (also, it is a class G amplifier, which vastly reduces output stage dissipation) When the triac...
  19. M

    How to test a Bi-Directional Triode Thyristor

    There is a link to the triac spec sheet in the OP.
  20. M

    How to test a Bi-Directional Triode Thyristor

    I guess you did not read the Carver white paper I linked to. Too bad.
  21. M

    Questions about modulation

    I wonder how you got the idea that AM and FM "don't care about it". The bandwidth is the frequency range required to enclose the carrier and all sidebands due to the modulation. The frequency variations of an AM modulating signal cause the AM sidebands to move in frequency. In AM the...
  22. M

    How to test a Bi-Directional Triode Thyristor

    That makes sense that it could be momentary. Then, pulling the darlingtons toward neutral fires the triac, which would occur through the 15K on the right side of the bridge. Then I can see how the opto might regulate the supply through the bridge. But, it's all conjecture at this point. I'm...
  23. M

    How to test a Bi-Directional Triode Thyristor

    http://carvermk2.com/Docs/Carver%20Magnetic%20Field%20Whitepaper.pdf talks about the features in the amp, including a high level of the power supply and the use of class G power rail switching. It also a great treatment regarding the real demands of high quality amplifier power supplies and the...
  24. M

    How to test a Bi-Directional Triode Thyristor

    @Jim I wonder about how the triac is drawn. They don't label the pins. R403 (10 ohms) to the power switch essentially breaks the path you drew, shorting the inputs to the darlingtons to neutral through the power switch. I assume the gate current comes through R403, but I don't understand how...
  25. M

    How to test a Bi-Directional Triode Thyristor

    D402 shorted is pretty serious. I assume you have measured all the transistors and the bridge in the power-on circuit and measured the thermal protection devices and internal transformer fuse. Also, the opto device. Do you see any voltage across the power switch when it is open (before...
  26. M

    How to test a Bi-Directional Triode Thyristor

    It IS a SMPS. Google triac waveforms. LOL --- I'm done discussing this with you.
  27. M

    How to test a Bi-Directional Triode Thyristor

    Think of it as a switching regulator. It is quite elegant, very efficient (no high power linear regulators wasting power), and probably VERY responsive to deal with transient voltage demands that the filter caps couldn't handle. As for a triac on the secondary, which winding on the...
  28. M

    Hardware Random Generators: Transistors vs Diodes

    Not my field. Maybe someone with current knowledge will respond.
  29. M

    Hardware Random Generators: Transistors vs Diodes

    This article addresses some of the issues you will face. http://www.ciphersbyritter.com/NOISE/NOISRC.HTM
  30. M

    How to test a Bi-Directional Triode Thyristor

    Nah, they are long gone. It was part of a failed effort at building a Recording Studio. I liked the sound of the 604E's better. I always like the heartbeat in the beginning of Pink Floyd's Dark Side of the Moon Album.
  31. M

    How to test a Bi-Directional Triode Thyristor

    You said Voice of Theatre. We built our own Voice of Theatres (cabinets) back in 70's. I didn't like the horn mids, added a JBL tweeter to brighten it up. Bass was good though. Drove it with a 600 Watt Phase Linear. We built one of the first 24-in 8-out solid state mixing consoles ever...
  32. M

    How to test a Bi-Directional Triode Thyristor

    Carver amps are special. When they say 200, they mean 200. Bridgeable professional quality stuff. There are probably so many subtle circuit tricks going on to deal with transient power surges, etc. Definitely worth fixing.
  33. M

    How to test a Bi-Directional Triode Thyristor

    How can you say that. You are essentially saying that if you remove all voltage regulation you will not damage anything. Do you understand how this regulator works and what part the TRIAC plays in it all? BTW traics are not simply "ON/OFF devices as described, especially in AC circuits...
  34. M

    How to test a Bi-Directional Triode Thyristor

    The triac is being used to regulate the power supply, so forcing it on will likely destroy stuff. There is an opto isolator above the bridge that provides feedback
  35. M

    PTC thermistor selection

    How about this? http://www.ti.com/product/LM57
  36. M

    How to test a Bi-Directional Triode Thyristor

    It is the power control and voltage regulator. It (via the TLP631 opto isolator) regulates the power supply. Not sure where I'd start measuring. If the fuse is not blown, I'd suspect something wrong on the other side of the transformer. The block diagram will be useful in tracking it down.
  37. M

    The Complex Exponential

    I may end up confusing things, but I want to take a stab at complex exponentials as representations of vectors. Take a vector of length 1 at pi/4 radians in the positive quadrant. The endpoint represents the complex number cos(pi/4) + i sin(pi/4). You can represent it simply as e^(i*pi/4)...
  38. M

    To adblock or not to adblock that is the question!

    While I will always use ad blockers because of ad-server sourced malware, an added benefit is the improved page load time and fewer outright hangs when there are no ads.
  39. M

    How can a PC detect the AC adapter brand?

    I'm not advocating hacking the protocol, but here it is described. http://hackaday.com/2014/03/03/hacking-dell-laptop-charger-identification/ Many chargers has some level of communication, for example getting an ipad to charge at full rate requires proper loading by the charger on the USB...
  40. M

    Measuring the EMF

    And that will be exactly equal to 9 volts. They are identical. What is the Voltage of a 9V battery? Answer in long ton furlongs per mole charge.
  41. M

    Measuring the EMF

    Hmmm --- I don't get it even if you are pedantic. EMF and voltage are measures of the same thing so can be used interchangeably. Doesn't matter what you call them, or what the units are, they measure the same thing. Can you agree with that? BTW, to be pedantic, saying the word voltage...
  42. M

    Hobbies of PF members

    Especially Spirited Away, but I like all the Miyazaki films. My Hobby (so I can play while others sleep):
  43. M

    Measuring the EMF

    Nobody is arguing that mechanical forces can't be created by electric fields acting on charges. Mechanical forces are off-topic and confusing the issue. At issue is the following statement: We have yet to hear of a situation where EMF (electromotive force) and Voltage are different. The...
  44. M

    Measuring the EMF

    It doesn't. At least not directly. Not sure yet what Jeff was getting on about with respect to EMF and Voltage not being used interchangeably in some situations. He has talked about electric fields, and mechanical forces, but still has me confused.
  45. M

    Measuring the EMF

    Jeff, I still don't understand your difference between emf and voltage. An electric field is a different animal (not an emf) and is not measured in volts. (rather volts/meter). Where can I not use emf (electromotive force) and voltage interchangeably?
  46. M

    Building a solar phone charger

    The basic architecture seems OK, but you need proper battery chargers and overdischarge protection. Regarding the LiPO A 5V regulator can be used to power a proper LiPO charger, but cannot charge it directly. You will get fire if you don't use a LiPO charger. I previously posted a link to...
  47. M

    News Funny pictures of politics and world affairs

    http://beggarstomb.net/wp-content/uploads/2014/07/01a-political-cartoons-22-07-11.jpg [Broken]
  48. M

    Voltage waveform analysis

    Not enough information. The question doesn't really make sense to me. Can you draw a schematic and show where this waveform was taken? 230V 50Hz is going through something that provides this waveform across a resistor? Are the numbers the actual voltage across the resistor? What is the 15W...
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