Need help understanding real world DC circuits.

Discussion in 'The Projects Forum' started by nraynor, Mar 21, 2013.

  1. nraynor

    Thread Starter New Member

    Mar 18, 2013
    I am very new to electronics and over the course of the last couple I have been frantically learning how all of this works. I am trying to understand how this device works in terms of what it looks like on a schematic. I have tried to draw out its schematic but I am pretty sure its not right.

    The device is one LED with a switch that has 4 different settings.The first flashes at 1 flash per second, the second is 2 quick flashes per second, the third is a constant quick set of flashes with an even amount of pause between flashes and the fourth is a solid beam of light with no flashes. Of course if you hit it a fifth time it turns off. Also if you press and hold the switch it shuts off as well.

    So far I know that the IC is whats controlling the different modes of flashes and the capacitors are what allow the LED to Flash.

    There are 3 resistors connected in the circuit
    • R1 - 1M ohms
    • R2 5.6 ohms
    • R3 - 330k Oms

    I am not sure what the IC is but it has 6 legs and and "00V7" printed on top.

    There are 2 capacitors that are unmarked but are different sizes.

    Its powered by 2 3v watch batteries underneath the board. I have attached a couple of photos to illustrate what it looks like.

    How do you identify what is in parallel and what is in series in this circuit? How is the T9 and G notation on the board positive and negative terminals for the batteries?
    Lastly, do you need to calculate the specific capacitance to use in a flashing LED circuit and find a capacitor with that value, or do you just need to use a capacitor larger than the calculated value?

    Thanks for any help in clarifying this.

    Oh, and all of the components are SMD's, not sure if that changes anything.
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    If you can push the same button several times to get different responses, the chip is most certainly a Microcontroller. The chip repeatedly checks if a button is pushed to change the voltage on one input pin while sending a string of digital pulses to the LED(s) with one or more output pins. The Microcontroller is programmed to respond according to the behavior you described, it is not a simple logic chip. You may be surprised to hear but these small microcontrollers cost less than $0.40 each and can respond any way you would Like. Just buy a Pickit3 programmer, download the software from and buy any microcontrollers you want from microchip. Set pins as digital or analog inputs to measure inputs from switches and sensors. Then set various output pins to 0 or 5 volts to trigger various Lights or displays or buzzers. Any whistle or bell you want at 1 to 20 million instructions per second.
  3. nraynor

    Thread Starter New Member

    Mar 18, 2013
    Thanks! I didnt realize those Microcontrollers were so custumizable. I am going to have to pick some up that test them out. Thanks for the help!