Recent content by mphotis

  1. mphotis

    digital Compass Chipset???

    Hi everyone, i am in desperate need of finding a 3- axis digital compass chipset. can anyone recommend the name of one such chipset BESIDES any product from Honeywell..... or even a 2-axis and 1-axis that i can combine. any help would be appreciated thanx
  2. mphotis

    light sensor help please

    hey guys, i got a problem... can someone give me a VERY simple circuit that allows me to switch a bp103 phototransistor on when it senses light from a standard red LED. the phototransistor is gonna be kept in a dark box with the led.when the led is off the output from the phototransistor will be...
  3. mphotis

    Bias temperature sensor?

    okay, thanx but now im working with a 5volt rail, how am i gonna get a -5V for    -Vs? im sorry, im pretty bad at this.
  4. mphotis

    Bias temperature sensor?

    Can anyone please tell me how to bias an lm35 temperature sensor to work in the range of -10 to +50 celsius? Thanx
  5. mphotis

    simple timer circuit

    Hi there i need help with a new project of mine. i need to design a timing circuit using a 555 timer. it requires that the timer gives a signal out for a specified time. once this time has elapsed, the signal must go to 0V. all i really want to know is, how do i control the timing period of...
  6. mphotis

    stopwatch's circuit??

    try this link..i found it useful.. http://www.electronics-lab.com/projects/oscillators_timers/014/index.html
  7. mphotis

    earth leakage protection

    Does anyone have any designs for a simple earth leakage sensing and protection device? would be appreciated thanx mike
  8. mphotis

    switching circuit

    Thanx alot...sorry im a bit slow with this sort of stuff. Im using a 12V NiCd battery. IM going to have a voltage divider network accross it to provide a reference range of 0-5volts. This will then go into an a/d converter which will convert the voltage to a 8-bit digital value(0-255). This...
  9. mphotis

    switching circuit

    Hi there... I really need help. I am busy designing a battery charger using a microcontroller. i need help with the attached circuit. When the battery is full i would like to be able to charge it using a far lower current. Im doing this using a simple circuit using two resistors in parralel...
  10. mphotis

    temp sensor cooling system

    The tests have been done in the lab. No harm comes to the motor, as long as the CO2 is sent down the right airgap. Besides, the CO2 is only supposed to be turned on once the motor gets too hot...so it doesnt freeze.....once the temp is back down to a safe temperature the CO2 switches off....so...
  11. mphotis

    temp sensor cooling system

    Hi there, ive been assigned a very interesting project. I need to design a cooling system for a go-cart using CO2 cooling. Im thinking of using an LM355 temp sensor to sense the temperature on the motor. when the temperature on the motor reaches a certain threshold level, i want a...
  12. mphotis

    environmental test chambers

    Hi there, Im doing a research project regarding testing a system in a controlled environment. I am using an environmental test chamber. I dont know how the thing works? Has anyone got any information regarding this. Any Datasheets, manuals or anything explaining to me how the thing works...
  13. mphotis

    5 volt regulated power supply HELP!!!!

    ive got another problem-maybe you guys can help me out.... im attaching a schematic of my supply so far. it works pretty well for medium loads 1k - 1000k. but as soon as the load goes quite low, like 10 ohms or lower, the output voltage stops regulating and starts to drop drastically. the...
  14. mphotis

    5 volt regulated power supply HELP!!!!

    mixos, as regards the first schematic you posted for me, do you have any suggestions to what the rating of the zener diodes should be?
  15. mphotis

    5 volt regulated power supply HELP!!!!

    Thanks very much guys. This stuff is really useful. :)
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