Search results

  1. audioguru2

    Deja-vu, reply to replies

    Hi Rhonn, It's spring time now where the new server is located. The bugs are hatching. ;D
  2. audioguru2

    RJ45 network card to IR

    Hi Ali, Welcome to our forum. ;D This is a confusing project, isn't it? ???
  3. audioguru2

    Another INVERTER we can talk about..

    Hey Sasi, The 1kW inverter will look like your little one when it uses a pair of those modern 330W Mosfets.  ;D
  4. audioguru2

    Electronic Stethoscope

    Hi Dazza, Are you going to make an ultrasound scanner?  ;D
  5. audioguru2

    Deja-vu, reply to replies

    I just received another e-mail reply to replies for a topic I started exactly 1 year ago today! It finished a few days later.
  6. audioguru2

    Deja-vu, reply to replies

    Hi Guys, Today I received about 8 e-mails from this site for links to topics that I was the last person to make a reply. A couple of topics that I replied to hours ago and a few that I was the last person to make a reply nearly a year ago! Is anyone else getting these phantom e-mails from the past?
  7. audioguru2

    Another INVERTER we can talk about..

    Hi CheeseE, [move]Perfect!
  8. audioguru2

    My girlfriend is getting into electronics

    f = 0.16 divided by RC. xR = 0.16 divided by fC. xC = 0.16 divided by fR. Forget about pi. E = I times R. I = E divided by R. R = E divided by I. P = E times I. P = I squared times R. P = E squared divided by R. hFE = Ic divided by Ib. Is this math?  ??? ??? It's just simple arithmatic...
  9. audioguru2

    differentiator

    No Kevin, The voltage of a capacitor that is charged by a constant current is an absolutely straight linear line. Its voltage rise has a constant rate of change with time increments, not following the curve when charging with a simple resistor. When a capacitor is charged by a resistor, the...
  10. audioguru2

    Low-pass Filter?

    Kevin, You can't use only two RC stages in a phase-shift oscillator, it needs at least three stages. Since the output load and the input impedance of the input to the inverting amplifier are low impedance, a buffer is needed and you might as well use RC stages having the same value.
  11. audioguru2

    Electronic Stethoscope

    Hi Dazza, You don't need to isolate many specific sound frequencies. As the doctor says in his article and are shown in 'scope pics in this thread, heartbeats are a pressure wave at a very low frequency, straining the lower limit of your hearing, microphones and he didn't mention the speakers or...
  12. audioguru2

    differentiator

    Kevin, An opamp has an extremely high gain. When it is used with negative feedback in a differentiator or integrator circuit, the capacitor is charged linearly with a constant current, not just an RC time-constant curve. Therefore the rate-of-change doesn't depend on the input voltage.
  13. audioguru2

    Another INVERTER we can talk about..

    Instead of using a half-dozen older Mosfets, why not use a modern one like the IRF2805 which is rated at 330W, and get 1KW from an inverter using only a single pair of them? ??? They are probably used in the $40.00 500W inverters that I can buy at my local tire store.  ;D
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Costa, I am sorry you can't get parts in your country. To be safe with ordinary opamps that have an absolute maximum total of their supply voltages of 36V, use a 21V or less transformer which will restrict the project's maximum fully-loaded output voltage to about 21V or less.
  15. audioguru2

    3V LED Chaser project

    Hi Dick, Sorry there isn't a pcb for this project. I have made many with Veroboard. Besides, I've advanced to the 6V Ultra-bright Chaser project, and have converted nearly all 3V ones to its pausing circuit, but still running on 3V: http://www.electronics-lab.com/projects/games/004/index.html I...
  16. audioguru2

    Electronic Stethoscope

    Hi Dazza, That's cool!  ;D Your little rascal's heart is racing like mine does after running around the block. It sounds like a frequency upshift circuit is used to convert the approx. 20Hz heartbeat sound up to a few hundred Hz. About 15 years ago I designed a voice encryption circuit for...
  17. audioguru2

    Electronic Eavesdropping Devices Detector

    Hi Duke, Your LM324 should work fine in this circuit. I see what you mean that the schematic and the PCB in this project don't correspond. I think both the schematic and pcb are wrong and the circuit will work well if you re-build it to agree with the VCO on the LM324 datasheet:
  18. audioguru2

    Another INVERTER we can talk about..

    Hi Alun, Source resistors might not even be required since Mosfets are PTC. If the stongest one heats, its current decreases. Besides, the SG3525 has an adjustable deadtime contol so the outputs won't conduct simultaneously.  :o The current in an inductor builds slowly, so would cause a strange...
  19. audioguru2

    Another INVERTER we can talk about..

    Hi CheezE, If you use 0.1 ohm resistors instead of the required 0.01 ohms ones, they will each waste 28W of heat and cause the output voltage to be about 24V less at full load. The same applies to the resistance of your battery connectors and wiring if they are only 0.03 ohms. You're going to...
  20. audioguru2

    Additional Information

    Hi Naveed and team, Good, it works. I am glad to have helped you.  ;D Q1 and Q2 keep the current constant at 10mA with only 1 LED or two or three. They also keep the current constant when the battery runs down. Q3 saturates well so that most of the supply voltage is available for the LEDs.
Top