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  1. C

    Make electronics : experiment 8 problem

    I have redrawn the circuit to make it much easier to see what is happening. D1 remains lit all the time after the button is pressed because when you push the button, the current goes around the circuit, through the top relay contacts and then through the LED and through the 680R resistor...
  2. C

    LED Types of 2015

    High wattage LEDs simply take more current and you finish up with enormous heatsinking problems with how to get rid of 50 watts of heat.
  3. C

    Make electronics : experiment 8 problem

    First of all, what is the circuit supposed to do?????
  4. C

    effect of humidity on a PCBs

    You may also have a section that has very high impedance.
  5. C

    Add DC offset to AC signal

    Firstly you have to provide details of the AC signal, its frequency and amplitude. And how it is delivered.
  6. C

    Just learning the ropes

    You should get some resistors 100k 220k 470k 1M and see what is produced on the screen. Then you will be able to measure something UNKNOWN.
  7. C

    effect of humidity on a PCBs

    You could have dirt between the tracks and this is causing leakage.
  8. C

    Is this circuit compatible for charging my gel cell?

    As you can see by the circuit, the maximum current is 1300mA when you use a 2 amp plug pack.
  9. C

    Watchdog Timers

    You can design a circuit that has to be triggered every 1mS so that it resets. If it is not reset, it reset the microcontroller. This is a HARDWARE WATCHDOG Most microcontrollers have an inbuilt watchdog that must be rest on a regular basis. This is called SOFTWARE WATCHDOG TIMING
  10. C

    Trying to solve exercise in art of electronics involving transistors and diodes

    Your circuit may or may not turn ON. It is not an engineered circuit. The LED in the emitters will work and then you can throw away the transistors, and you can throw away the top resistors.
  11. C

    Help with debounce code

    That's why I code in .asm Frustration has left me 5 years ago. Basically you need a 5mS to 10mS delay loop to eliminate debounce problems. The simplest is to create 3 consecutive sub-routines and the micro gets caught in these loops (sub-routines) and will not emerge until the button has been...
  12. C

    Will this a 12VDC 1A Adapter break my LED?

    The LED and resistor will only take 20mA, even if the adapter is capable of delivering 5 amps. It is the resistor that limits the current to 20mA
  13. C

    Is this circuit compatible for charging my gel cell?

    "Not rubbish, Colin. AK was referring to the current-sense resistor in the post #1 circuit." This make two of you that know nothing about electronics. This is MY circuit and it is only designed for very low current to charge a 1.2AH battery. Don't you think I know how it works?
  14. C

    Is this circuit compatible for charging my gel cell?

    24v supply is far too high for the circuit. "A 1 ohm resistor sets the charging current at 0.65 A. 0.65 x 14 = 9.1 W. Again, gonna need a heatsink." What rubbish - you need to read my basic electronics course.You know nothing about electronics.
  15. C

    Trying to solve exercise in art of electronics involving transistors and diodes

    "Keep in mind that you cannot saturate a transistor when emitter resistors are used." This is incorrect. There are a lot of slight inaccuracies, badly described statements and omissions in the article on P63 of The Art of Electronics. It is no wonder the student does not understand what to do...
  16. C

    Help on how to test this device

    The core has to be touching - otherwise the transformer will heat up too much.
  17. C

    Trying to solve exercise in art of electronics involving transistors and diodes

    Use common-emitter stages and not emitter followers. Connect the first via a switch and resistor and take a diode to the second transistor. Connect a sw to the second via a resistor.
  18. C

    Circuit design for high resistance sensor measurement

    Humidity sensors already have internal amplifiers and buffers and come out 1k.
  19. C

    Circuit design for high resistance sensor measurement

    What sensor has an impedance of 10 meg? You are going to get enormous problems with humidity interference.
  20. C

    Adjustable Schmitt Trigger Circuit Help

    Designing a transistor schmitt trigger circuit for this requirement is not an easy thing to do.
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