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  1. yes absolutely but i have only time for on/off and haven't any parameters like resistors and capacitor for using formulas. i think i should revers working. because when you have resistors and capacitor you can use 555 calculator for result. and result are space and mark time
  2. Hello dear friend could you help me for designing a LED blinker with two properties: 5 seconds LED on and 2 seconds LED off and repeat. how can i calculate space time and mark time for these R1 , R2, C1 for making 5 and 2 seconds?
  3. hi i have problem with my micro controller (PIC) board for control of camera (turn left and right). in this circuit used 7805 for making 5voltage for all component of circuit and camera (cctv work with 5v). but when turning on this circuit , av receiver can't receive signal from camera. but when i disconnected this camera from circuit and plug in to different 5v power supply work very well and i have good signal in AV receiver. i guess problem is in power supply (maybe noise ). have you any idea for this circuit that work with one 9-12v adapter in input voltage but have two apart 5v in circuit? that i use micro controller board and camera separately. thanks
  4. lm7805 question

    can you tell me more about this statement about these values "The value isn't critical but if you make it too small you risk it being inadequate to damp oscillation. If you make it too big, at least with a single capacitor, you run the risk of the high frequency impedance of the capacitor being too high. " damp oscillation and high frequency impedance ? thanks
  5. lm7805 question

    what is the different between c1 and c2 will be 100uf instead of 10uf?
  6. hi friends please see this attachment. can you tell me why use c1 and c2 for lm7805 and why in other config we use capacitors with different values. this pictures use for pic micro controller and LCD power supply. thanks
  7. 2n2222 resistor value

    thanks hero999 is there any formula for this issue? my coil is 57ohm
  8. hi friends please show me how can i calculate resistor value connected to base of 2n2222? thanks
  9. temp. sensor ds1820

    hi can anyone know about ds1820 and how can i work for getting temperature from ds1820? any calculation need? i want to use pic micro controller and i just know more about ds1820 thanks
  10. change gas sensor sensitivity

    hi if you read this post you will see i said MQ4(gas sensor) and i want to know can i use potentiometer after output of this sensor for change sensitivity? thanks
  11. change gas sensor sensitivity

    hi friends please see this attachment. can i use potentiometer for change MQ4 sensitivity before transistor ?
  12. hello friends can you suggest me a simple amplifier for amplify output of ISD1420? i need to hear the voice in the house only but i need good quality. i think 1w or 0.5w is good. thamks
  13. i have laser pointer (use in presentation) and i want to transmit data up to 1meter (zero and one logical method ) , with receiver sensor. for first in this issue i need circuit for amplify signal (fast switching) in receiver. look at this schematic !! i know how can i make signal in transmitter with micro controller but i have problem with using 2pin receiver sensor. if you have any idea for amplify signal in receiver circuit?
  14. hi friends have you any idea for sending data (0 or 1) with laser diode to receiver diode with PIC micro controller and indicate to LCD 2*16 characterize lcd?? thanks
  15. hello friends i have question can we make a dc motor driver like 4bit step motor with DAC808? can you suggest a circuit? thanks