Search results

  1. audioguru2

    help! transistor as diode

    Hi Vishu, When you use a transistor as a "super diode" with its base connected to its collector, when forward-biased it is still a transistor with its rated current gain (check its Vce spec) and therefore produces a low forward voltage drop. Since a transistor's base-emitter junction has such a...
  2. audioguru2

    help! transistor as diode

    Hi Vishu, Simply connect the base of the transistor to its collector. Do not exceed the reverse-biased voltage rating of its base-emitter junction which is only 5V to 7V for silicon transistors. ICs use transistors connected as a diode this way for low-voltage voltage references. They are better...
  3. audioguru2

    voltmeter with more accuracy

    Hi Sharath, Instead of using a fragile wire that might break or burn-out, you could use a dual transistor package. One of the transistors is the heater and the other is the temp sensor. You can get them in a sturdy metal package.
  4. audioguru2

    60W Linear Amplifier

    Hi Ante, Where is the project's author? We are just guessing here. I think that you are correct. I thought that the project is for VHF because its tuning coil has only 2 turns (I was thinking about those FM transmitter toy projects). But now I realise that the tuning coil has a core and its...
  5. audioguru2

    voltmeter with more accuracy

    Hi Sharath, Welcome to our forum. Our projects section has two digital voltmeter projects that use the same ICL7107 IC. Which one are you talking about? The "Digital Voltmeter" project has its reference voltage set to 0.1V, just like the datasheet for the IC shows, but uses an extremely...
  6. audioguru2

    How to get low level from high (audio)

    Hi Stuee, Maybe the line out of your head unit is low-impedance and can drive many amps that have a high input impedance. Their spec's will say. If one amp feeds the other amp, you won't have the advantages of having separate amps: 1) If you feed the 2nd amp from the output (attenuated) of the...
  7. audioguru2

    Electronic Stethoscope 2

    Hi again Doctor Emad, If you want to try my corrected circuit using a dual opamp, the pins on the opamps package can be connected like this:
  8. audioguru2

    Question on the Plants Watering Watcher circuit

    Hi Oli, The "non-soil" is called Pearlite or Vermiculite. I doubt if it is conductive. I have seen potted plants growing in that light-weight white stuff. Don't you think that my circuit will fail if they were watered with "pure" water?
  9. audioguru2

    Question on the Plants Watering Watcher circuit

    Hi Oli, I have been thinking that my circuit probably won't work if the plants are watered with distilled water, and the use of organic instead of chemical fertiliser. I will try it with synthetic soil too. I was amazed at the low resistance of my plain and activated-charcoal-filtered (no...
  10. audioguru2

    60W Linear Amplifier

    Hi Ante, I just assumed that this RF amp was rated at "Peak or Maximum" power, like car audio amps, to make the power number twice what is actually true. So with a 42W input from its power supply its actual output is 30W which is reasonable (a little more than 71% efficiency). Its Mosfet is not...
  11. audioguru2

    60W Linear Amplifier

    Nice new project. http://www.electronics-lab.com/projects/rf/027/index.html Sorry, but I am not a ham radio operator and are just curious. Others will be curious too. What frequency or band does this amplifier operate at? Are its output power and harmonics legal?
  12. audioguru2

    Electronic Stethoscope 2

    Hi Doctor Emad, Why did you change so many parts of the preamp? Now it is nothing but a mid and high audio frequencies noise generator, as you reported. 1) The KIA358 (LM358 sub) opamp has a high noise level and crossover distortion. A low-noise opamp was recommended. 2) Its gain is too high so...
  13. audioguru2

    Keys finder circuit

    Hi Jazcannon, Welcome to our forum. You don't want an actual piezo buzzer, which would have a built-in oscillator, you need a piezo transducer. The circuit already has an oscillator and a buzzer won't work as a microphone. Bad translation, I guess. I don't know where you are but my Canadian...
  14. audioguru2

    DIGITAL FILTERS

    Hi Shiva, You don't understand that all the sounds are added togerther, then sampled. So the single sampling frequency is digitally modulated (digitized) with all the sounds. A processor can separate anything from the digitized information. A similar thing happens with a simple loudspeaker. It...
  15. audioguru2

    Electronic Stethoscope 2

    I am anxious to see your "noise generator circuit". No negative feedback like the original circuit has in a couple of places?
  16. audioguru2

    Electronic Stethoscope

    Hi Doctor Emad, Did you use the KIA358 for both U1 and U2? I checked, and a KIA358 is the same as an LM358, which is a dual opamp. It is noisy like a 741 and has crossover distortion because it uses very low supply current. Can you get an NJM072B which is made by New Japan Radio? It is a dual...
  17. audioguru2

    AA battery power rating

    Yeah, nearly dead ones! (non-rechargeable kind) Ante is correct, they start life at 1.5V (or even 1.6V).
  18. audioguru2

    Question on the Plants Watering Watcher circuit

    Hi Oli, Your measured pulse widths and battery current are a little more than twice what I measured, which is due to your change of the oscillator's frequency from my 2KHz to your 800Hz. Your pulse width keeps increasing with an inter-probes resistance more than 100K, which makes me believe that...
  19. audioguru2

    oscope to tv

    Hi Ante, How's your prize UV LED? Did it give you a nice tan? Mine is still on backorder. I'm glad that I didn't swim to Greece to try and get it. Your author's images are fuzzy because the bandwidth of his TL082s video amp buffer and inverter is only 100KHz. Video needs at least 40 times...
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hurray Marek, You fixed it! I am glad to have helped. ;D Please let us know its performance.
Top