Search results

  1. audioguru2

    best voltage and current regulator

    A 3V transmitter won't draw much more than only 20mA, an FM stereo one about 30mA. Use an LM317 linear regulator.
  2. audioguru2

    Input signal for LM3915. need help.

    Correct. I used the transistors to provide very high charging currents to the capacitors in the peak detectors so they charge very quickly.
  3. audioguru2

    Input signal for LM3915. need help.

    You don't need the transistors I used with a slow average detector. just connect the R8 negative feedback resistor directly to pin 7.
  4. audioguru2

    Lowpass filter for subwoofer

    This site has a few very good subwoofer projects and articles: http://www.sound.westhost.com/projects.htm
  5. audioguru2

    Input signal for LM3915. need help.

    They assume that you know so they don't show power supplies for the opamps. Each opamp is an inverter with the non-inverting input connected to ground. Therefore the outputs must swing equally negative as well as positive. Ordinary opamps are shown that don't work if their input voltage is...
  6. audioguru2

    Lamp contol with logic circuit

    A darlington pair has a voltage drop which is a high percentage of this 5V system.
  7. audioguru2

    Input signal for LM3915. need help.

    Good. Normal. My peak detector responds very quickly, holds the level for a moment then slowly drops away. It drops away quick enough to show the loudness of each spoken word and bounces with music. The 10th LED should light only if the level is higher than the amount to cause all other LEDs to...
  8. audioguru2

    about mixer

    You didn't attach a circuit with a bass control.
  9. audioguru2

    Greetings from Ottawa

    This site's new server blocked my IP address, but I found a way to beat the list! As happened many times in the past, it seemed that the server wan't working.
  10. audioguru2

    Lamp contol with logic circuit

    I repeat: "The resistors at the outputs of the gates are not required since they don't do anything." A BC107 has the same chip as a BC547 but is in a metal case. They don't have enough current gain and aren't powerful enough to drive your high-power light bulbs. A BC547 could use a 6.8k resistor...
  11. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Neo, Using the recommended 30VAC transformer for this project, the unregulated positive voltage is about 40.4V which is much too high for a 12V fan. If a 5.4W resistor was added in series with the fan to reduce its supply voltage then there might not be enough extra current in the resistor to...
  12. audioguru2

    defective project

    There are many projects that don't work. It would be impossible for the staff of E-Lab to test each one before it is posted. We are trying to fix them as they are worked-on by somebody who complains about a defective project.
  13. audioguru2

    infrared transmittion

    IR can be directly modulated with AM or FM audio. Frequently high frequency subcarriers like 100kHz and 200kHz are used then FM modulated for stereo.
  14. audioguru2

    Lamp contol with logic circuit

    No. The resistors at the outputs of the gates are not required since they don't do anything. Yes, but the BC547 won't have enough base current to drive a lightbulb or a relay.
  15. audioguru2

    Lowpass filter for subwoofer

    Hi Frt, Welcome to our forum. ;D What are you asking about the project? It has a few mistakes that are discussed in the other thread about it. A link to the other thread is at the bottom of the project.
  16. audioguru2

    Greetings from Ottawa

    Hi Serge, I am also a Canadian. I retired early a few years ago and am enjoying collecting a small pension from the government and fooling around with electronic things that I have always wanted to make. My career was in audio systems engineering and I still enjoy it. You are a MIS? What is that?
  17. audioguru2

    Lamp contol with logic circuit

    Hi Circuity, Logic gates don't need pull-down resistors at their outputs. The output of a 74LSxx TTL gate is guaranteed to drive an 8mA load from a positive source down to 0.4V. Your circuit still has very high current lightbulbs. A 74LSxx TTL output can drive the base of a transistor through a...
  18. audioguru2

    infrared transmittion

    Hi Ryan, Your signal looks like AM modulation but I think it would have just the two frequencies mixed together instead of modulation and would look like this. AM modulators I have seen change the supply voltage of the carrier oscillator like this one.
  19. audioguru2

    infrared transmittion

    Hi Ryan, Do you want to amplitude-modulate the carrier? Your circuit doesn't modulate, it just mixes the signals together. Also, your 4kHz modulation frequency is reduced by the attenuator of R2, C3 and the very low impedance of the transistor's emitter.
  20. audioguru2

    Input signal for LM3915. need help.

    My circuit uses a peak detector with a single supply. An average detector is in the datasheet and needs a dual supply.
Top