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  1. audioguru2

    0-30V Stabilized Power Supply

    The performance of a low voltage (less than 5.6V) zener diode is poor. It conducts current when it has half its rated voltage and its voltage changes with temperature changes.
  2. audioguru2

    Fm transmitter

    You didn't post a better transmitter. The MAX2606 has a low supply voltage and a low supply current so its output power is low. Its range might be a few hundred metres to a very sensitive home stereo tuner or car radio with nothing in between or across the street to a cheap clock radio.
  3. audioguru2

    0-30V Stabilized Power Supply

    Why will ZD3 reduce the positive supply to U1 and U2 when the transformer is 30VAC? It might cause the max output voltage to be less than 30V when the current is max at 3A. The 30V transformer might have an output of 31.5V without a load then its peak voltage is 44.5V and the rectifier bridge...
  4. audioguru2

    0-30V Stabilized Power Supply

    Yes, the 160VA transforer is able to allow the output current of the project to be as high as 3.77A. Even the designers of this kit did not calculate the amount of voltage losses there are. They said to use a 24V transformer but then the measured max output voltage at 3A was only about 25VDC. In...
  5. audioguru2

    Audioguru's Electronic Stethoscope Help

    It is designed to drive headphones, the kind that completely cover your ears. If you use a loudspeaker then it needs to have more gain which will cause acoustical feedback howling because the microphone will hear the speaker and the sound will go around and around. EDIT: Where will you find a...
  6. audioguru2

    audio amplifiers

    You must say what is your speaker's impedance and how much output power you want. The LM3886 can produce 68W into 4 ohms with a plus and minus 28V supply. It dissipates about 42W so its total power is 110W and the current in the 56V supply is 2A. The LM3886 can produce 50W into 8 ohms with a...
  7. audioguru2

    0-30V Stabilized Power Supply

    Connect the + output to ground then the - output is a regulated variable negative supply.
  8. audioguru2

    Active filters

    I was wrong. A high-order Butterworth lowpass filter is almost perfect but a second-order Butterworth filter attenuates signals above about half its cutoff frequency. Curves are shown in Google but they are difficult to see because they have orders fro 1 to 5 all at the same time.
  9. audioguru2

    circuit distortion

    The transistor has high distortion because it is controlled by current but the input is a low impedance voltage. Then its output is exponential. Also, the transistor is running wide open with no negative feedback. The distortion is about 3% when the transistor has lots of negative feedback but...
  10. audioguru2

    Active filters

    An RC low-pass filter is -3dB at the cutoff frequency and starts reducing the level at 1/5th its cutoff frequency. Two buffered RC filters in series are -6dB at the cutoff frequency and start reducing frequencies that are 1/10th the cutoff frequency. A Butterworth 2nd-order (two poles) active...
  11. audioguru2

    circuit distortion

    Yes, but its distortion is as much as 40%. Yes, but since its open-loop gain at 1kHz is as much as 10,000 times, its distortion is extremely low. Nope. The transistor produces severe distortion and the opamp doesn't. Look at what a single transistor does to a sine-wave:
  12. audioguru2

    Active filters

    Cascaded RL or RC filters have a droopy response. An active filter adds positive feedback to make the response sharp at the cutoff frequency. Then the response is flat up to the cutoff frequency then a sharp drop past the cutoff frequency. The multiple-feedback bandpass filter opamp circuit I...
  13. audioguru2

    Need A Help Circuit Diagram "Power Saver Supply"

    Chinese people advertise a device that is a "Power Saver". It is simply one capacitor that is at a very high price. It is a scam. It cancels the inductive effect of electric motors in a home which improves the power factor. But its value does not match the actual amount of inductance that your...
  14. audioguru2

    7805 and AC-Adapter

    The battery in my car can supply up to 750 Amps to the starter motor when it is very cold. But the 7805 regulator that is my cell phone charger doesn't care. The 750A battery is connected directly to the input of the 7805. The interior light in my car is also connected directly to the 750A...
  15. audioguru2

    0-30V Stabilized Power Supply

    The original circuit had many parts overloaded. The new version fixed the overloads by using parts with a higher power rating. The original circuit did not meet its spec's. The new version does. The new version fixes all the problems with the original version. U1 has a 5.6V zener diode at its...
  16. audioguru2

    Random Q's: Audio Overlay,

    You must not connect the speaker outputs of the radio and the scanner together because they will fight each other and probably produce smoke or blow a fuse. Instead you must add an audio mixer circuit to the radio, probably beween the volume controls and amplifiers. Modern radios have an...
  17. audioguru2

    0-30V Stabilized Power Supply

    Yes. Trimpots have an arrow marked "CW" that points to the pin that the slider goes toward when the shaft is turned clockwize.
  18. audioguru2

    0-30V Stabilized Power Supply

    No. The voltage and current setting pots are voltage dividers, not adjustable resistors. The calibration trimpots are adjustable resistors.
  19. audioguru2

    Help me >>>Circuit Diagram for 12vdc inverted to 220vac generate sinewave

    I think he wants to power his entire city with a little inverter that must not be expensive.
  20. audioguru2

    0-30V Stabilized Power Supply

    Hi Besarmatis, It is easy to see how to connect a pot when you look to see that it is a semi-circular resistance track and a rotating wiper along it. The resistance connects to the end pins and you can see which end is connected to the wiper pin (the middle pin) when the control is turned...
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