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  1. MP1

    Variable Power Supply

    Click the Articles" button at the top of the page and in the "General" group, you will find a LM317 tutorial with a calculator that will help you calculate the voltage output. As Zeppelin has mentioned, you are limited on current unless you add additional hardware. and/or heatsink. MP
  2. MP1

    IC 555 instead of IC 50240

    I haven't been following this thread, but yes, a microcontroller could be programmed to give you the sounds you need. Each output pin could give you a different voice. You should understand, however, that a 555 and micro will both give you a pulse or square wave without additional hardware to...
  3. MP1

    Auto dimming problem

    The link to this project is here: http://www.electronics-lab.com/projects/automotive/006/index.html Handcannon, What is the rating on the pots you have used? In a car circuit, you must use high watt rated pots or you will have the problem you are discussing. These pots are limiting voltage to a...
  4. MP1

    Begginer Project?

    You could get a lot of good tutorial information by searching the web for Vellum kits. This is a brand name. They always put a very nice soldering tutorial in the beginning of their projects. B1 is Battery #1, R1 is resistor #1, C1 is Capacitor #1, U1 is IC#1 (or Integrated Circuit #1), the...
  5. MP1

    lesr sade from iraq the inverter 500w

    Hi Lesr, Congratulations on your project! As you have found, there is a lot of latitude when making a square wave inverter. You can use various op-amps or most any digital gate to provide the signal to the transistors. Thanks for posting the pictures of your project. MP
  6. MP1

    MOVED: Heating elements

    This topic was posted in the wrong forum. It has been moved to Circuit/General Requests. http://www.electronics-lab.com/forum/index.php?topic=9921.0
  7. MP1

    Begginer Project?

    It all depends upon your level in electronics. It would be a good project to learn. It will certainly give you soldering practice and experience with schematics. What problems are you having with the parts lists in the schematics? MP
  8. MP1

    circuits

    Ben, You probably have oxidation on the copper strips on the board. This is easy to overcome. Go to your local electronics store and get a small bottle of liquid solder flux or a solder flux pen. Put a liberal amount of flux on all surfaces that you want the solder to adhere to before applying...
  9. MP1

    Temperature display with ICL7107CPL

    Gayan, These values should work fine. You can also use combinations of capacitors to equal a different value if you wanted. A lot will depend upon how smooth the DC is from your power supply. If you have problems, go to a larger value on the input of the 7805 to smooth out the signal better and...
  10. MP1

    circuits

    I assume you are discussing this project: http://www.electronics-lab.com/projects/rf/003/index.html In the instructions, it tells you that soldering the components together is critical. Also, note that since you are dealing with RF frequencies, you must shield your board so that stray signals do...
  11. MP1

    Temperature display with ICL7107CPL

    Hi Gayan, It looks fine. That is exactly what I was describing. Actually, it looks like you saved a step by connecting the sensor to the floating "In Lo" so that inverting the signal was not required. Good work! In regards to the battery draw, there isn't much you can do about it. But I think...
  12. MP1

    circuits

    You might want to first try soldering all connections and shielding the circuit in a metal box. I don't know if this is the cure, but I am sure it will help improve the signal. MP
  13. MP1

    Temperature display with ICL7107CPL

    Gayan, I think you will have a problem with the decimal point since a display of 60.0 would normally be done on the 200V scale. If you float the input and make the reference voltage adjustable, you should be able to come up with a scale that allows you to go from 0 to 60 with your input voltage...
  14. MP1

    Temperature display with ICL7107CPL

    That shouldn't cause come of the segments to be brighter than the others. This could be due to the displays you are using or you might have damaged them. Some designs do not use the diodes to drop the voltage to the displays and some do. You might have a display that requires more current and...
  15. MP1

    Temperature display with ICL7107CPL

    Hi Gayan, I missed your question earlier about the meter displaying 30, etc. R4 should give you enough adjustment to trim the voltage scale, but not the actual range of the meter. If you are using the 2 volt scale, you are not going to display a 30. You will need to change the input scaling so...
  16. MP1

    Temperature display with ICL7107CPL

    You can invert the voltage with an inverting op-amp, ICL7660, or any other charge pump circuit. You will need to use positive and negative supplies on the 7107 to read the negative voltages. (Your attached schematic looks ok for this) In regards to the question about "Common", you can float this...
  17. MP1

    help, making Phone line indicator

    T1 is in the "Transistor-fet" library. The resistors are listed by size. You probably already know they are in the "Discrete" library. A 7.5 should work ok for these. There is also an LED library with many different LEDs. You want to choose the one you will use. You can always print the...
  18. MP1

    help, making Phone line indicator

    which parts? MP
  19. MP1

    Temperature display with ICL7107CPL

    Hint: Invert the input voltage to the 7107. 60.0
  20. MP1

    circuits

    Ben, If you will grip the transistor leads with needle-nose pliers while soldering, the needle-nose pliers will act as a heat sink and keep the transistor from getting over heated. In regards to the circuit layout problem, are you sure the problem is capacitance? I don't know what your circuit...
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