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  1. audioguru2

    0-30 Vdc Stabilized Power Supply

    The original Greek kit and the first Chinese copy wrongly said to use a 24V/3A transformer that does not work and becomes overloaded. Its voltage is too low for the project to produce 30VDC at 3A and its voltage is too high for the opamps with a low maximum supply voltage rating of only 36V. The...
  2. audioguru2

    0-30 Vdc Stabilized Power Supply

    If you use a 24V/4A transformer then its maximum allowed output is 24 x 4= 96VA. Then the project maximum output current must be calculated with the 34V peak voltage (96VA/34VDC= 2.8A). You can simply calculate how much heating (volts times Amps) a 2N3055 will survive by its thermal spec's and...
  3. audioguru2

    0-30 Vdc Stabilized Power Supply

    If you use fine and coarse controls then one will always be in the wrong position. Use larger knobs instead. Higher output current will cause a heat problem in the output and driver transistors. The improved version of this project already uses two output transistors to share the heat produced...
  4. audioguru2

    Power supply

    AC might be Air Conditioner? The power required depends on its efficiency. A high efficiency AC uses much less power than an old low efficiency one.
  5. audioguru2

    Using 1N4148 As A Temperature Sensor

    A zener diode is used with reverse bias voltage. A temperature sensing diode is used with forward voltage that is completely different. Look at the datasheet of a 1N4148 diode. Its forward voltage is shown at -40 degrees C, at +25 degrees C and at +65 degrees C. The forward voltage drops as the...
  6. audioguru2

    DIY a Compact RC Switch

    The circuit will never have a negative voltage in it. P1 will smoothly give 0V to +5V to pin 2 as it is rotated. The input current of pin 2 is so low that a 10k or 20k pot will make no difference. R4 limits the T1 base current to  only 0.3mA then tie relay might not be activated if it needs...
  7. audioguru2

    ELECTRIC BOAT MOTOR PROJECT

    You mentioned relays. Then you do not want speed control? Jerky on-off is called "bang-bang control" in cheap kids toys. What will happen to the motor when it is running forward at full power then you suddenly change it to run in reverse at full power? The fuse will probably blow to save the...
  8. audioguru2

    INA331IDGKT Cannot work in My Project

    You forgot to attach the schematic of your circuit for us to see anything wrong.
  9. audioguru2

    0-30V PSU - prblem with current limiter

    A 24V transformer has a voltage too high for the TL081 opamps. Use a transformer with a lower voltage like 15V. Replace the opamps that were strained. Replace the old fashioned 2N2219 with a modern BD139 transistor on a real heatsink. Replace the single 2N3055 output transistor that might be...
  10. audioguru2

    0-30V PSU - prblem with current limiter

    The original project has many parts that are overloaded and they fail soon. We modified it to make it work better and to be more reliable.
  11. audioguru2

    Sports Training Timer

    We will help you if you build or design a circuit that does not work properly. But it sounds like you want somebody to design a circuit for you. Somebody might do it.
  12. audioguru2

    0-30 Vdc Stabilized Power Supply

    We talked about fixing the cheap Chinese Banggood kit on another website and I do not want to talk about it again.
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    I think the kit from Banggood and copies of it are selling at a clearance price today because it has been replaced with a better kit maybe with its errors corrected. Of course the new kit costs much more and comes with voltage and current displays. 
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    The original circuit has many overloaded parts and cannot produce 30VDC at 3A. It is also missing the calibration trimpots that are used in the improved version that can be set to exact maximums of 30.0V and 3.0A.
  15. audioguru2

    Solar Powered Water Pump

    None of your voltages match. The solar panel produces only 0.5V. The battery produces only 3.7V and is charged from about 5V or 6V. The pump needs 6V. A battery charger does not dump power when the battery is fully charged. It simply turns off the charging.
  16. audioguru2

    Practical High Quality (transistors)

    ebay means "manufacturer's rejects" and "sweepings off the floor". Don't buy anything from ebay, instead buy from a reputable and reliable Western electronics parts distributor. Haven't you see a datasheet of an old 2N2222 transistor? Like all transistors its hFE is a range of 1 to 3 times and...
  17. audioguru2

    0-30 VDC Stabilized Power Supply 0.002-3 A

    I can buy a transformer with any voltage that I want. A 28VAC one or a 30VAC one will work in this modified circuit and the circuit will have a maximum regulated output of 30VDC at 3A. If you use a transformer that is 24VAC then the maximum regulated output from this modified circuit will be...
  18. audioguru2

    The error occurred in using of XC6371A

    The datasheet shows how the output voltage is marked. It could be from 2V to 7V in 0.1V increments. I think yours is 2.3V.
  19. audioguru2

    design a LED driver circuit

    31W a lot of power in the small area so the LED will get extremely hot. How will you cool it? A number of lower power LEDs will be easier to cool. An LED sets its own voltage that you cannot adjust. Its current sets its brightness.
  20. audioguru2

    Blink LED using FM radio

    The circuit is too simple to be an FM radio.
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