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  1. gorgon

    relay not working in comparator circuit

    Due to the resistor divider you'll only have around 2V or less over the relay. To get a proper drive from the transistor you should move the relay to between the collector and the +9V, connecting the emitter to 0V. To drive 350 mA you'll need a heavier drive Circuit. The hFE of the...
  2. gorgon

    Tactile button

    Normally the tactile type of foil buttons are Incorporated in the foil in some way. They are dome shaped metal springs and when you press them them you get the click when the dome is partly inverted. When released they return to the dome form. The electrical connection can be inside the foil...
  3. gorgon

    Microcontroller with external memory mapped peripherals

    The Freescale Kinetis series has several variants of external memory interface, and is relative new. The STM STR9xx series also has the external memory interface, but I don't know how they are placed on the 'chip life cycle'. If you plan to use existing memory mapped hardware, you should...
  4. gorgon

    what is difference between memory address and memory location

    A memory location is related to the format of the data stored. It can span parts of the data covered by a memory address, to including the data of several addresses. It all depends on the architecture of the system in question.
  5. gorgon

    UART

    You need to clarify your question, and expand the information. Do you want to communicate from a PC to several devices over the same serial communication port, or do you want to expand the number of serial ports(UARTs) controlled by one PC?
  6. gorgon

    400 volt monitor

    If you have no hysteresis on the on/off switch, turning off the charger, the load on the capacitor will reduce the voltage and turn on the charger again. The resistor network you have connected to the capacitor will discharge it. How fast is depending on the value of the resistors. To stop that...
  7. gorgon

    400 volt monitor

    It all comes down to the charger of the capacitor. I don't think it will tolerate an extra 25W of load, resulting in a burned out charger, and/or no charged voltage. If it should happen to work, those extra watts will heat in vain twice, first in the charger and then in the resistor.
  8. gorgon

    Dodgy Power Amp Design

    You should DC bias the IC1b buffer input to the virtual GND. The value of the resistor will load the input and you may need to increase the capacitor. As far as I remember the normal way to feed a speaker from an asymetrical driver, was to use a big capacitor between the speaker and the...
  9. gorgon

    lighting a 7 segment LED

    You can use optical filters to increase the contrast of the displays. This will also help in daylight viewing.
  10. gorgon

    Analog signal 4-20mA

    Why you mix TTL into this picture, I don't know. (0)4-20mA is an analog signal in nature. The max value of the loop resistance is purely dependent on the overall voltage overhead in your current loop. For a 4-20mA loop the tranducer will normally need around 10V of the loop voltage to...
  11. gorgon

    lighting a 7 segment LED

    The Vf drop depends on the colour. Normally 2.1V should be yellow or green. Red is around 1.7V and blue and white 3V +. 20mA for Ultra Bright could be more than enough, depending on what you want to do.
  12. gorgon

    lighting a 7 segment LED

    No offence to the posters, just an observation.
  13. gorgon

    lighting a 7 segment LED

    It could be interesting to see the actual schematics used in this applicarion, since all the comments are based on the commenters own definition of what they understand. The OP does not say anything of how many 7-segment displays he use in this application, and from the text it looks like...
  14. gorgon

    Any integrated circuits cookbook?

    As far as I can see, the CMOS Cookbook is from 1997. If you want to go into retro TTL, the TTL cookbook should be ok even today. There are few newer ICs in the TTL flavor. For the CMOS variants you should get a cookbook, and then go to the different manufacturers websites to get updated...
  15. gorgon

    circuit for pulse generation

    Reza, Could this be an Electro-Osmotic pulse generator?
  16. gorgon

    Looking for recommendations

    Circuit Cellar, Elektor, Servo.
  17. gorgon

    Analog signal 4-20mA

    The reason for the 4-20mA system is the supply of the transducer. It is normal that they also need an voltage overhead of around 10V to function properly. 0-20mA is normally used when the transducer has it's own Power supply. Many transducers use either <4mA(2-3) or >20mA (21-25) as a...
  18. gorgon

    2 X 4-20mA signals????

    Something like this? http://www.inteccontrols.com/pdfs/SIA07A.pdf
  19. gorgon

    About STM32

    How about taking a look here: http://www.st.com/web/catalog/tools/FM116/SC959/SS1532/PF217965?s_searchtype=partnumber
  20. gorgon

    Question in Char Separating

    Normally an array of char is called a string. So you need to search for string manipulating functions.
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