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  1. Audioguru

    Different Pass filters for different speakers.

    A very cheap speaker uses only a capacitor feeding the tweeter in its crossover network. The cutoff slope is very gradual so a lot of low frequencies are still poorly produced. Since you have an amplifier for each type of speaker then you need an active crossover circuit that uses many resistors...
  2. Audioguru

    XR2206 DIY signal generator kit.

    An analog oscilloscope shows time per grid line so simple arithmetic will give the frequency. When a multimeter is set to show frequency then its input draws almost no current. The fuses in a multimeter blow out only when it is set to measure a current too high for it. Maybe you tried to measure...
  3. Audioguru

    Understanding a regulator circuit with MOSFET and Zener-Diode

    Maybe Emin does not know which pin is the drain or the source?
  4. Audioguru

    Problems with a simple power supply

    Unregulated 24V is too close to the recommended maximum of 26V. The datasheet shows plenty of power with a 21V supply.
  5. Audioguru

    Problems with a simple power supply

    The peak of the 19VAC is 26.9V but the fullwave rectifier drops the DC output to 24.9V if the capacitance is very high. But since the capacitor is only 820uF then the massive current of 5A is causing high ripple which reduces the average DC voltage. The light bulbs reduce their resistance when...
  6. Audioguru

    DC adapter in place of AC?

    If the "7.2V" battery is Ni-Cad or Ni-MH then all 6 cells are fully charged to 1.5V which is a total of 9.0V. The charging circuit might need an additional 1.7V for a total voltage needed of 10.7V. The original 9VAC charger produced a peak of 9V x 1.414= 12.7V and the fullwave rectifier dropped...
  7. Audioguru

    Voltage divider capacitive dimmers

    A high value variable capacitor was used 60 years ago in an AM crystal radio. Its maximum value was 365pF which is 0.000365uF. It was pretty big and expensive because it was mechanical. You want one that is 630 thousand times larger and you want it non-polarized. For many years a triac fed...
  8. Audioguru

    Electronic kart

    A 12V to 220V 3000W transformer is huge, heavy and expensive. Its 12V input is AC, not the DC from a battery. If the transformer is 90% efficient then its 12V input is 277.5A AC!
  9. Audioguru

    Please Help reusing speakers

    Your photos are too small to see anything and you did not label what they are. Does the TV have connections for external speakers or does it have connections for an external amplifier that drives speakers? 1) What is the first photo that shows 11 RCA jacks? 2) The middle photo shows a "thing"...
  10. Audioguru

    I'm trying to rig a bike horn to an alarm clock

    The 2N3906 PNP transistor turns on when the input goes to ground. Then the Mosfet also turns on which turns on the horn. It is backwards. Instead you need an NPN common-emitter transistor to turn on a P-channel Mosfet that turns on the horn when the input is about +1.5V.
  11. Audioguru

    I'm trying to rig a bike horn to an alarm clock

    You copied the circuit from an "Instructable" that was designed by a kid who knows NOTHING about electronics. So of course the alarm blasts when it should be quiet and it is quiet when it should blast.
  12. Audioguru

    Can i plug a 115v power bar to 110v - 240v extension?

    Most power bars do not convert 250VAC down to 125VAC. Will your laptop survive if it is fed a voltage twice as high as it needs? Most do not.
  13. Audioguru

    Amplifier problems, Hum, preamp and filter

    The datasheet of the obsolete (it is not made anymore and is not available) TDA2005 amplifier shows that its maximum allowed output current is 3.5A which is produced when it is bridged with a 4 ohm speaker and a power supply that is about +16V. When its speaker is 8 ohms then it can use an 18V...
  14. Audioguru

    Piezo Preamp EQ

    The high end is boosted if the value of the capacitor in the gain control circuit is too small. You must calculate the capacitor value for the cutoff frequency you want like this:
  15. Audioguru

    Amplifier problems, Hum, preamp and filter

    The audio transformer will not work and might burn out if you connect it to the output of an amplifier. IF you need isolation then it connects to the amplifier input. Your schematic does not show the extremely important power supply voltage. Its maximum is about 14.4V when its two amplifiers...
  16. Audioguru

    Multimeter reading of LED

    Many new people do not read the datasheet of an LED (maybe because cheeep LEDs on ebay do not have datasheets) so they see the forward voltage is 2.8V then calculate the resistor for a 2.8V LED. But the minimum voltage for some of those LEDs is probably 2.4V so the current will be too high or...
  17. Audioguru

    Human safety system in drainage

    Here in Canada we are civilized and do not have those problems. Garbage is collected weekly or bi-weekly then it is buried. Drinking water comes from pipes in the ground which are fed with sanitized pure water. Human waste goes into the sanitary sewer system and is processed to be safe before...
  18. Audioguru

    Solar Panel Charge Controller

    It won't work. See the other forum you posted it on.
  19. Audioguru

    Combining 2 audio outputs into 1

    I assume that your electricity is Canadian or American where there is live, neutral and ground connections on each AC receptacle. One of the two prongs on an appliance (your TV) might be larger so that its plug can fit only one way so that the chassis of the appliance can be grounded with a...
  20. Audioguru

    Combining 2 audio outputs into 1

    The TV is never completely turned off since its on-off remote control receiver is always powered. Have you tried reversing the TV's 2-prong AC plug? Maybe your mains receptacle has its live and neutral wires connected backwards (since some 2-prong plugs cannot be reversed)?
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