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  1. audioguru2

    High precision voltage regulator

    Hi Dody, You don't give any details about what you want and why, so you have few replies. 1) What are you measuring and why doesn't it have its own regulation like an audio amplifier? 2) Line regulation? 3) Load regulation? 3) Ripple rejection? Just a short piece of wire will drop more than only...
  2. audioguru2

    amplifier audio/video

    Hi Dragon, Welcome to our forum. My car came equipped with crappy little 20 ohm full-range speakers. When I replaced them with two-way 4 ohm speakers with real big magnets the sound quality improvement was enormous! Most home speakers are 8 ohms and car speakers are 4 ohms. Full-range speakers...
  3. audioguru2

    4W FM Transmitter

    Hi Spleblem, Most answers to your questions are explained in the other recent post anout this 4W FM transmitter project here: http://www.electronics-lab.com/forum/index.php?topic=338.0 You are going to need a refrigerator for T2 or a clip-on heatsink and a big high-velocity fan. The circuit...
  4. audioguru2

    radio transmitter

    Hi Spleblem, There are many simple 1-transistor FM transmitter circuits on the web but they don't work very well as explained in the post with my transmitter design. I made mine work fairly well! I had to add some parts to a simple circuit to fix most of its problems.
  5. audioguru2

    LED driver

    You can see and download the entire article for free if you enter in a Google search, Silicon Chip Online-white LED driver.
  6. audioguru2

    Puggy Potty Alarm

    Hi Alun, The 555 has a fair amout of voltage loss in its output because it uses cascaded emitter-followers to obtain a high output current rating. I forgot to include your complimentary pair of emitter-followers in my previous calculation, so the total output voltage loss is about 4 X 0.7V =...
  7. audioguru2

    Infrared

    Kevin, Infrared is used for wireless headphones and speakers. Since the response of a phototransistor is not very linear with amplitude, usually FM modulation and detection is used. I have seen huge arrays of IR LEDs in conference rooms for language translation. They are beamed to IR detectors...
  8. audioguru2

    Puggy Potty Alarm

    Hi Alun, I have re-calculated a loss of 2.7V from typical curves of the LM555 from its datasheet. Therefore the transformer will receive only 1.8Vp-p when the circuit has a 4.5V supply.
  9. audioguru2

    Puggy Potty Alarm

    Hi Alun, A 9V battery has six AAAA cells inside. Additional AAA cells would just last twice as long as the 9V battery. When the sound level begins to drop too low, only replace the 9V battery and replace the AAA cells the next time. Your idea of using a stepup transformer and only a 4.5V...
  10. audioguru2

    Puggy Potty Alarm

    Hi CRE, So you had a shorted capacitor and now a fried IC. Maybe they were damaged when you powered the circuit with two batteries in series. The circuit by Alun provides automatic reset. The 1st 555 is a few seconds timer. It is triggered when the contacts have a current path from wetness...
  11. audioguru2

    Transducer digital output to analogue

    Hi John, It's a pressure transducer with a positive DC differential analog output that is powered from a positive supply. Digital has nothing to do with it. 1) Its wheatstone bridge schematic is shown in your Image 3-D. 2) Its 4 terminals (2 for power and 2 for differential output) are shown in...
  12. audioguru2

    Transducer digital output to analogue

    What is the transducer and which type of digital output does it have? Its datasheet wil show how to decode it, if you don't understand it please post it here.
  13. audioguru2

    4W FM Transmitter

    Hi Radiopirate, On the 1st page of this thread, I posted the spec sheet for the 2N2219 transistor. It shows that it is not possible for it to dissipate more than only a couple of Watts with any heatsink. If it is not tuned properly in this circuit, it will try to dissipate many Watts. :o Use...
  14. audioguru2

    Help: I want to build my own Intercom.

    Hi Masterleous, 1) What kind of mic, electret or dynamic (coil and magnet)? 2) Is the noise coming from acousical feedback howling, background sound, electronic hiss or mains hum and buzz (from the wiring)? 3) What power supply voltage are you planning for the mic preamp? 4) Does your LM386...
  15. audioguru2

    Puggy Potty Alarm

    Hi CRE, All your opamps are about the same.
  16. audioguru2

    Puggy Potty Alarm

    Hi Alun, Your favouite "rail-to-rail" Cmos opamp has some serious limitations with its output current. Like all Cmos ICs, its output current capability reduces as its supply voltage is less. In this circuit, it is driving the high capacitance (maybe 15nF) of a piezo transducer which is a fairly...
  17. audioguru2

    PWM

    The PWM in my Plants Watering Watcher-2 and chaser projects has a range in the thousands.
  18. audioguru2

    Re: Alun's low voltage alarm

    Hi Alun, That should get the project corrected but your corrected schematic was deleted from the 1st topic, and the quad comparator is actually an LM339.  ;D
  19. audioguru2

    Re: Alun's low voltage alarm

    Hi Alun, Click on "Contact" at the top of each page. Mike (his handle is Mixos) is the site's owner in Greece. His biblio was on the home page but I can't find it anymore.  ;D
  20. audioguru2

    4W FM Transmitter

    He, he. Your refrigerator was too small! ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D  ;D ;D ;D ;D ;D ;D  ;D ;D...
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