Search results

  1. audioguru2

    Plants wattering watcher

    Four AA Ni-Cads for a battery is fine.
  2. audioguru2

    geophone kit circuit reqest

    Hi Steven, Are you going to add an LM3914 or LM3915 bar-graph IC and 10 LEDs like in the kit you showed?
  3. audioguru2

    How to add a mute system to an OpAmp

    Like I said, an ordinary transistor would probably rectify the signal when it is turned on which would make low-level distortion. JFETs have been used for muting frequently.
  4. audioguru2

    10 A FET

    I have recently heard about a Gate Turn Off SCR type of semiconductor, but I haven't seen one and haven't seen a list of their part numbers.
  5. audioguru2

    Plants wattering watcher

    Hi Cody, You have had a lot of things mixed-up in your circuit. What kind of battery do you have? Is it strong enough to supply 80mA when all 10 LEDs are lighted in the bar mode and still have 5V or more? On the LM3915, pin 7 and pin 8 should not have the same voltage like you have. Pin 7...
  6. audioguru2

    How to add a mute system to an OpAmp

    Hi Shahriar, The ordinary transistor has very reduced current gain when the signal ihas reversed polarity so the muting will be a little rectified. Use a jFET like I said. It is a voltage-variable resistor and with the low level from the mic it will have low distortion even if you ramp the...
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Multeri, Some resistor values will need be be reduced so that they still supply the same current with a reduced input supply. You would need to re-design nearly every one. Also, the main voltage reference is +11.2V, so its opamp would need a supply of at least 13.2V. For +15V output at 3A...
  8. audioguru2

    CA3094 IC DATA REQEST

    Hi Steven, The datasheet for that very old IC is here: http://www.datasheetarchive.com/datasheet.php?article=1098621
  9. audioguru2

    Plants wattering watcher

    Doesn't the circuit light any LEDs? Please measure the voltages of pins 1 to pin 9 of the LM3915. Please sketch how you connected your 2k pot and 510 ohm resistor. What color and voltage are your LEDs? Disconnect the cathode of an LED from the pin of the LM3915 and connect it to a 1k resistor...
  10. audioguru2

    RAMSEY 10A FM NEED HELP PLZ

    Hi Tinu, Ramsey's project doesn't work very well with its old BA-1404 IC that drifts its RF frequency all over the place and harmonics of its 38kHz stereo interfere with its RF. Rholm discontinued its BA-1404 IC and replaced it with a much better selection of ICs. Silicon Chip magazine has a...
  11. audioguru2

    Plants wattering watcher

    The project does not have a 510 ohm resistor in it. Which resistor on the schematic? R1= 470k, R2= 100k, R8= 47k and two resistor values and a 2.5k trimpot are shown on the modified schematic.
  12. audioguru2

    0-30 Vdc Stabilized Power Supply

    The current regulator U3 might be bad, or a wrong value resistor was used for R7, R21, R17 or P2. C8 might be shorted. If Q1 has its emitter and collector pins reversed, then it would act like a 7V to 8V zener diode as it has reverse breakdown which would limit the output voltage of U2. But it...
  13. audioguru2

    Plants wattering watcher

    I guess you built the circuit that I recommended earlier. The ICs and voltages are good and the LM3915 should be lighting a few LEDs. The number of lighted LEDs should be adjustable by turning the 2.5k trimpot. Did you change any parts values?
  14. audioguru2

    op amp response time

    All opamps have differential inputs, including the LF411. You wanted to know its speed with only a single input used, not as a differential with two inputs used.
  15. audioguru2

    From breadboard to....

    Hi Fatal, I make circuits on Veroboard which is also called stripboard. It is perforated and has strips of copper printed wiring running in one direction and all in parallel. Half of a pcb is already done by the strips and the resistors, capacitors, ICs and transistors bridge the strips where...
  16. audioguru2

    audioguru fm transmitter

    When the antennas are the wrong length and your meter is not the same impedance as an antenna, then you aren't measuring RF power output, you are measuring the voltage swing that a transmitter can put into whatever impedance is the meter. Make each antenna the proper length with a fairly long...
  17. audioguru2

    Electronic Stethoscope 2

  18. audioguru2

    85dB

  19. audioguru2

    How to add a mute system to an OpAmp

    A switch on the output.
  20. audioguru2

    How to add a mute system to an OpAmp

    I muted the background music in a huge intercom system with a series resistor and a jFET to ground. Half of the input signal was fed to the gate of the JFET for very low distortion and the muting was made with a ramp for fading the music down then fading back up to avoid clicks.
Top