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  1. audioguru2

    NiMH Battery Pack Charger

    Go to www.maxim-ic.com and look at their 48 battery charger ICs. http://para.maxim-ic.com/cache/en/results/5099.html You could also see the rechargable battery tutorials at www energizer.com and at other battery manufacturer's websites. Without a load, a discharged battery will probably measure...
  2. audioguru2

    rf oscilaotrs

    One of your many topics was for the datasheet of a Hitachi 555. It is not Cmos and won't work in that detector circuit.
  3. audioguru2

    Bigginers Handbook

    Does anybody know the name of this Beginner's Handbook? Maybe one of us has it and can post it again.
  4. audioguru2

    stereo Transmitter

    My FM transmitter doesn't have a wide enough audio bandwidth for stereo. Its audio response drops at around 15kHz but stereo needs a response up to 53kHz. The circuit you have is basically copying what is inside an inexpensive BH1415 Rohm transmitter IC. But your circuit uses an inaccurate 555...
  5. audioguru2

    rf coil

    A coil and a capacitor makes a bandpass filter. They can be series or in parallel
  6. audioguru2

    rf oscilaotrs

    Did you make the circuit which I attached in your other post? You said you made something that didn't work. Was it that circuit that didn't work? Then list the part numbers of the parts you used and the battery's voltage. Maybe you used an ordinary 555 IC instead of a Cmos 555 IC so it will work...
  7. audioguru2

    Darlington TR

    Hi Shahzad, Look at the datasheet for the 2N3904 to see its typical spec's with 1mA collector current. 1) HFE= 230. 2) Vbe= 0.68V. Yours is much too low. Your 900 and 85k resistors aren't standard values. The current in R1 and R2 should be about 10 times the transistor's base current...
  8. audioguru2

    Variable DC Power Supply

    The book called "The Art of Electronics" is pretty good. It is available in our Resources Forum. I downloaded it and saw it for the 1st time recently.
  9. audioguru2

    Darlington TR

  10. audioguru2

    Ignition coil driver circuits and experiments

    With kilo-volts flying around in arcs, more protection provided by a MOV is good to have.
  11. audioguru2

    Ignition coil driver circuits and experiments

  12. audioguru2

    electronic switch

    Hi Almog, Welcome to our forum. A CD4017 is a 10-steps sequencing IC. It steps to the next step with each pulse from your switch. When it reaches the final desired step then it is reset. All you need in addition is a debounce circuit for the switch and a battery to power the circuit. The...
  13. audioguru2

    amplify the power (infrared)

    Maybe the phototransistor is being saturated by visible light. Is the range better when it is dark?
  14. audioguru2

    Working required

    If you want to learn how the circuit works, look at the datasheet of the old 74174 IC. Why not attach pictures to your posts instead of storing them on that different site?
  15. audioguru2

    Problems lately accessing this site

    Anna's pic is just fine. ;D Today this site loads pretty quick.
  16. audioguru2

    NiMH Battery Pack Charger

    Before charging begins, a voltage measurement should be made that the battery isn't already charged. During charging, a voltage measurement should be made to determine if the battery has a shorted cell. It seems that looking at the datasheet of a battery charger IC from Maxim or another...
  17. audioguru2

    How to detect a 0.4 volt without affecting the source

    The input current of an ordinary opamp is nanoamps. One opamp in the dual opamp LM358 can detect 0.4V above its negative supply voltage. A Jfet input opamp like a TL081 or TL071 has just about no input current but will need positive and negative supplies. A Cmos opamp also has just about no...
  18. audioguru2

    Emulate a 10k thermistor

    A PNP transistor in series with the lowest resistance you need can replace the thermistor. A resistor in series with the base of the transistor limits the base current and a modulating voltage applied to the resistor controls how much it conducts. Your sketch is confusing with the power supply...
  19. audioguru2

    Digital logic circuit design

    I recommend that you cut the project into pieces: 1) Keyboard to display. 2) Above to transmit and receive the data along a wire. 3) Make FM tx and rx circuits.
  20. audioguru2

    500W 12v to 220v Inverter

    100 ohms, 1/4W resistors are very common. Use them. You should never use a resistor at its rated power dissipation, it will be too hot. Its rated power is its absolute max allowed.
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