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  1. audioguru2

    op-amp low frequency pulse generator

    Whatever teaching-about-capacitors method Walid's teacher used that made him think that capacitors are a DC short is wrong. Maybe the teacher was completely mixed-up and was really talking about inductors. Maybe Walid is completely mixed-up about capacitors and inductors. ???
  2. audioguru2

    Input signal for LM3915. need help.

    Yeah, it fixes a problem I had with an old sound meter project with two LM3915's like yours, but it showed either a very low level or a very high level. This one always indicates between 0 and 10.
  3. audioguru2

    op-amp low frequency pulse generator

    Hi Indulis, Of course the capacitor's voltage is at ground the moment power is applied to the circuit, then the comparator waits an extra amount of time for its voltage to reach the Schmitt-trigger threshold voltage. It is like the famous 555 type of 1st half-cycle time extension. Speaking of...
  4. audioguru2

    op-amp low frequency pulse generator

    You were taught wrong. Even the main filter capacitor following the rectifier in a power supply connects to ground and is continuously charging and discharging. It doesn't short to ground. A capacitor has a low reactance at high frequencies, not a low resistance. Snap action is quick (without a...
  5. audioguru2

    3V LED Chaser project

    Hi Nick, Welcome to our forum. ;D You can use any project on this website for anything you want. I also have a 6V Ultra-bright Chaser project here that has a few extra features: 1) It uses extra-ultra-bright blue, green or white LEDs that need its 6V battery. Their brightness's are absolutely...
  6. audioguru2

    CRITISIZE THESE CIRCUITS

    Oh yeah, Switch contacts bounce maybe 20 times for each push of the button. Your "transmitter" needs a "debounce" circuit for the pushbutton switch so it makes a single pulse to the LED.
  7. audioguru2

    CRITISIZE THESE CIRCUITS

    I guess you didn't read the datasheet. The reset gate needs a pulse-stretcher.
  8. audioguru2

    CRITISIZE THESE CIRCUITS

    Pin 8 is Vcc. ICs don't have a "before" and an "after", the bypass caps connect with short wires as close to pins 8 and 1 as possible. Pin 1 is ground. I didn't look in the datasheets for the pins' functions and timing for the ICs. You can do that and try the circuit to see if it works. The 4518...
  9. audioguru2

    WOW... look?

    Hi Nick, Are you serious about wanting to make a taser, or are you just selling all that stuff? If you look into electronic circuits, they have an awful lot more than just batteries in them. Wouldn't it be nice if anyone could makea taser,  a TV or an Apple ipod from just a couple of batteries? :o
  10. audioguru2

    LED Voltage Formula vs. Voltage Divider

    Hi Mum, Welcome to our forum. ;D An LED doesn't need a voltage divider. It operates with current, not voltage. An LED sets its own voltage drop. If a second resistor was in parallel with an LED to make a voltage divider then that resistor does nothing but waste power, and cause the other...
  11. audioguru2

    Input signal for LM3915. need help.

  12. audioguru2

    Latching comparator help

    Your transmission gate doesn't turn off. Maybe its pin 6 is blown if you tried the opamp without the clamp diode. Maybe it is blown by having an input or output voltage that exceeds its supply voltages. What is the voltage swing of its input signal? What is the DC voltage of its load? How much...
  13. audioguru2

    EL WIRE---if you know anything about it click here!!!URGENT...sorta

    Sure, you blew-up that part and probably more parts in the inverter by giving it too much input voltage.
  14. audioguru2

    LM317 Variable power supply

    I clearly explained about the operation of an LM317 regulator. Your 36.8V is way too high for a 5V fan, 9V meter and an LM317 regulator. The fan uses 110mA at 5V when it is running, but might need 1A to start. It probably won't start running when fed through a 300 ohm resistor. Try it. The...
  15. audioguru2

    LM317 Variable power supply

    Hi Um, A 24VAC transformer might be 28V without a load. The rectifier charges the filter cap to the peak voltage minus two diode drops which calculates to be 38.2V. The datasheet for the LM317 shows examples of extra-cost LM117 regulators but you can easily calculate resistor values for an...
  16. audioguru2

    Push button controlled Potentiometer? How?

    Thanks, Vernon. I saw a video of the Case of Hope gem on the web brightly lighting its pink LEDs then dimming. I would have added a heatbeat to it. ;D
  17. audioguru2

    Push button controlled Potentiometer? How?

    Hi Vernon (Twizted), You promised to send me some blue LEDs as thanks for the free circuit design I did for you? You don't reply to my e-mail about it? ???
  18. audioguru2

    security system project

    Hi Buddie, Which method of detecting motion do the sensors use today that are available in hardware stores? PIR! I haven't seen (heard?) an ultrasonic one since I was a kid and today I am an old geezer. Hi Vish, I don't have a Security System Project.
  19. audioguru2

    Latching comparator help

    You don't have a resistor to ground at pin 6 of the transmission gate, so it never gets a logic low.
  20. audioguru2

    Input signal for LM3915. need help.

    It is the top of the resistor ladder that applies reference voltages to the comparators in the LM3915. Its voltage sets the voltage thresholds at the input that turn on the LEDs. If Rhi is at 5V (and Rlow is at ground) then a 5V input is needed to light the 10th LED. The voltage of Rhi changes...
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