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  1. audioguru2

    Electronic Eavesdropping Devices Detector

    IR is a form of energy, it doesn't have a frequency that is tuned. Anything with some heat in it transmits IR. The sun transmits a lot of IR as do stoves and fires. Your body transmits some IR. You must say how strong is the IR you want to detect. IR is analog modulated with sound and is used...
  2. audioguru2

    simple question about batt chargers

    You cannot do that! A Ni-Cad or Ni-MH battery is charged with a current. If you connect a fully charged two-cell battery (about 3.0V) to a 5V power supply then the battery will overcharge with a huge current. The huge current will cause the battery to overheat and vent its chemicals or explode...
  3. audioguru2

    TV and VCR Tuner

    Sure they are the same since they both receive TV. There is no reason for them to be different. In order to prove it then you must find the parts list of a TV and a VCR that uses the same tuner.
  4. audioguru2

    Electronic Eavesdropping Devices Detector

    Of course not. This is a high frequency radio circuit. IR is light, not radio and is modulated at low frequencies. For years, IR remote control uses an IR receiver IC. What do you want to do with IR?
  5. audioguru2

    Photodiode to extend LED on settop

    Watches don't use LEDs because they use a high current. The three watch batteries in a keychain flashlight last only about 1 hour. Maybe you could power your photodetector/LED idea with two AAA rechargable batteries and recharge them every few days.
  6. audioguru2

    Can i get some help in a project>><

    A Linkwitz-Riley active crossover network has two Sallen and Key lowpass or highpass filters in series. You can see this project about it http://www.sound.westhost.com/project09.htm and look-up Sallen and Key filters in Google.
  7. audioguru2

    Electronic Eavesdropping Devices Detector

    Hi Webharsh, Welcome to our forum. ;D The circuit amplifies and detects very high frequency radio signals. More amplification won't allow it to detect IR which is light that cannot be seen. To detect IR you need a light detector such as a photodiode, phototransistor or IR receiver IC.
  8. audioguru2

    Digital stereo channel selector

    A CD4052 or 74HC4052 is a stereo select one from four analog switch IC. Its selections are made with a 2-bit binary word. If its output is lightly loaded with a fairly high impedance then its distortion is fairly low.
  9. audioguru2

    FREQUENCY COUNTER

    Actually, your circuit has not received the weak incoming call to your cell phone. Your circuit has receiver the strong transmission from your cell phone when it transmits that it is turned on and is ready to receive a call. I don't know if cell phone transmit and receive frequencies are in...
  10. audioguru2

    plz paste these sheets if u can

    I look at www.datasheetarchive.com to get most datasheets. Most of your part numbers are incomplete which makes them hard to find. I know that the 723 is actually an LM723. The 2N3055 should be easy to find.
  11. audioguru2

    FREQUENCY COUNTER

    To measure and display cell phone frequencies up to 1.8GHz then you would need to be a microwave RF engineer and use parts made for cell phones which you can't purchase.
  12. audioguru2

    rf coil

  13. audioguru2

    TV tx

    A video transmitter block diagram is shown in Google, in Howstuffworks and in many other websites. For TV, a video transmitter is an AM transmitter with a mixer to mix the sync pulses with the wideband analog video. Colour TV is a little more complicated since there are a few completely...
  14. audioguru2

    Darlington TR

    I don't remember because I studied that stuff about 42 years ago. I have designed only two RF circuits in my life. Look in Google or ask your teacher.
  15. audioguru2

    TV tx

    low distortion, low noise, wide bandwidth. Yes. Use an FM transmitter and an FM receiver. The receiver can simply detect any modulation or can detect a certain tone frequency that has modulated the FM carrier frequency.
  16. audioguru2

    Use a speaker as a microphone while useing it as a speaker

    Hi Sarma, Most of the intercom systems, speakerphones and boardroom teleconferencing systems that I worked with used a fixed hybrid 2-wire to 4-wire converter plus half-duplex voice switching to avoid acoustical feedback. The newer more expensive systems used a fixed hybrid 2-wire to 4-wire...
  17. audioguru2

    Use a speaker as a microphone while useing it as a speaker

    Hi Sarma, I have adjusted the balance of telecom hybrid networks many times. It is a big compromise with the capacitance, inductance and resistance of each telephone line often being different and with the conditions changing. You are lucky to obtain a max attenuation of unwanted signals of only...
  18. audioguru2

    TLO74 ic data reqest

    Hi Steven, All quad opamps use a standard pins numbering system with 14 pins. Even the very old LM324 is the same.
  19. audioguru2

    TLO74 ic data reqest

    Hi Steven, The TL074 is a quad opamp made 1st by Texas Instruments and is copied by many others. The 1st link in a Google search is TI's website's introduction page for the TL071 single, TL072 dual and TL074 quad opamps and their datasheet. It can be used in any opamp circuit that uses a supply...
  20. audioguru2

    Digitally selected outputs for LM317

    The LM317 is the summing amplifier. The D to A converter just gives it some resistors for its ADJ terminal to ground.
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