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  1. Audioguru

    Connecting Battery to multiple consumers

    Consumer? I am a consumer and nobody has ever connected a battery to me. I think he means a load. I hope the loads are not LEDs where one load is three 2V red LEDs in series (6V) and another load is one 3.2V blue LED. Then the current must be changed for each load, not the voltage.
  2. Audioguru

    Solar Powered Display Cabinet

    A solar panel is made for sunlight and its current is rated when the panel is facing directly to the sun at noon on the equator of earth. Indoor lighting produces 1/100th or 1/1000th the current. Use a battery or a wall wart but since you do not know how much current your project needs then you...
  3. Audioguru

    Solar Powered Display Cabinet

    You do not make sense: 1) Solar powered. 2) Indoors so there is no solar (no sunshine). 3) Grid tied so the circuit is powered from the electricity grid (so no solar panel). A string of LEDs operate from a certain voltage and use a certain amount of current but you did not say the voltage and...
  4. Audioguru

    Need some help on this Project

    The circuit and maybe the website it comes from is full of errors so why is it going to be your "learning how to solder" final project? 1) The entire project is completely useless. The relay can be driven by the wire loop and a battery directly, without the IC, transistor, capacitor, resistors...
  5. Audioguru

    Loud music from over-the-fence is causing offence...

    I didn't play the dogs barking and I couldn't remember which song was Whitney Houston's "I will always love you" so I played it. It gave me goosebumps and made my hair stand up. She sang it very well didn't she? It is a shame she is gone. Like PINK, I also cringed when Aguilara messed up...
  6. Audioguru

    Help with small solar panel setup. Volts but no amps.

    The solar panel is cheap and is Chinese then its "70mA" is a lie. It has a plastic window that gets sunburned which blocks light. A good solar panel has a glass window. If the solar panel was Western-made then it would produce 70mA at 3.0V in summer sunlight at noon, when it is pointing directly...
  7. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    It is too bad that the Chinese companies copied the defective original circuit without testing it, and too bad that they did not number the parts on the pcb.
  8. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    Here is one reason that U3 gets hot:
  9. Audioguru

    understanding discrete circuits

    Q3 does not "get switched on", instead it is always conducting, a little more or a little less with the audio AC. Its base is not modulated by the amplifier output at the speaker, instead its base is modulated by the input signal and is biased by R2 and has negative AC and DC feedback from the...
  10. Audioguru

    Loud music from over-the-fence is causing offence...

    If you amplify their sound and feed it back to them then you will have acoustical feedback howling since a sound goes in your mic and out your speaker then back in your mic again and out your speaker again over and over. Your noisy neighbours might like it but you will not like it.
  11. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    Some voltages are wrong. The 0V black lead of the meter should connect to the negative wire of C1. Are your opamps TLE2141? 1) U1 voltages are correct. 2) Pin 3 of U2 is wrong. It connects to P1 so it should go from 0V to +11.2V as P1 is turned up. Maybe pin 3 is shorted to something or maybe...
  12. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    You have too many threads about this miserable power supply and have a Chinese kit with none of its parts numbered and made from the original defective circuit and some changes made by Paul on his blog. Paul's schematic (with skinny wires that are hard to see) shows the 10V zener diode the same...
  13. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    I cannot see where pin 7 (the positive power supply pin) of U3 connects to. It should connect as shown on my schematic. If pin 7 of U3 is about 30V (is it?) then the added 10V zener diode is not destroyed then since the output of U3 is only 5.2V it is in current regulate mode and lights the...
  14. Audioguru

    CO detector engine shutoff

    You mentioned a CD4013 flip flop IC. Have you seen how low is its output current? Much too low to drive a relay but enough for a transistor between the CD4013 and the relay. Do you have a 555 timer IC? It has lots of output current to drive a relay and can be used as a monostable to lengthen a...
  15. Audioguru

    Encrypt tv

    Years ago, I had fun de-scrambling pay-per-view on cable TV. Later, people were de-scrambling pay satellite TV but I never did. I think the Iran, North Korea and China governments encrypt TV and ban out-of-country internet because they do not want their people to see how nice things are away...
  16. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    The 1N4740 zener diode will work well if it is not connected backwards. Measure that it has 10V across it. The driver and output transistors voltages are messed up. Disconnect and bypass them to see if the U2 opamp works properly like this:
  17. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    Isn't your pcb from Bangood? Then it is for the old original defective Greek kit. My many mods added a 10V zener diode to U3 to reduce its supply voltage and the pcb is made for an Oriental driver transistor (and maybe the little transistors) that have different pin layouts than the Western...
  18. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    Check the datasheet for the output transistors to see its pins. I hope you did not buy cheap fake or defective transistors and opamps from ebay. Edit: You never said what the output voltage is. It should go from 0V to +30V with the voltage setting pot and with the current setting pot turned up...
  19. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    I assume that your voltage measurements were with no load on the project and with the voltage and current setting pots were at minimum. 1) The emitter voltage of the NPN BD139 should be about 0.7V less than its base voltage, not 4.8V higher. 2) The load on the output of U3 is a 10k resistor...
  20. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    You can put a 60W light bulb in series with one 240V transformer wire then test the output voltage up and down from the project.
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