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Applying wave to voltages

Discussion in 'General Electronics Discussion' started by Electro132, Oct 15, 2013.

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  1. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    Hi,

    I have this project in my mind where the power/voltage supply is 1.2 V which is turned into
    - 70 mV using resistors in the "M' ohm range.

    The problem i am having now is how to add it to the IC and combine it with the wave pattern. I know that a NAND will work with a 555 but wanted to make sure if it was correct. Also i wanted to know if a Vresistor would change the volume and a Vcap would change the current flow?

    help me out here please
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,445
    2,628
    Nov 17, 2011
    I'm sorry, at a first glance your post doesn't make any sense at all.

    Please explain in detail what you are about to do. A schematic of your circuit will be of unvaluable help to understand the circuit.
    - which IC?
    - which wave pattern
    - what is "it"?

    This will not work at all. No resistor can convert a positive voltage into a negative voltage, irrespective of the values of the voltages and resistor(s).

    Any gate will "work with a 555". The question is: what is the gate intended to do, how does it interact with the 555.

    - what is Vresistor?
    - what is Vcap?
    - which current flow do you want to change?
     
    Last edited: Oct 15, 2013
  3. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    The IC i am using is a 555 timer which generates a sine wave
    Can you explain what you are referring to in your last question please?


    Sorry buddy but i already did that so it is possible. (You just switch them)


    Well its intended purpose is to be used as part of a sequence. Let's just say i have attached 9 'NAND gates' and then used -70 mV as the signal that i want it to be carried on. This should be repeated in a continous manner (the sequence starts from 1 - 9 peaks, then another 1 - 9 peaks, and so on.) as long as i have the button pressed down to allow voltage into the sequence.

    The 555 is the start of the sequence and the NAND gate is the end of the sequence. What i want it to do is work with the voltage i am using it with while also allowing me to control how much volume there is on the sine wave.


    Vresistor = Variable Res
    Vcap = Variable capacitor
    The current coming out of the IC


    Basically i want a schematic which will allow -70 mV as the power source through to the IC with volume control (potentiometer) and be able to control how much volume is coming out of it
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    11,445
    2,628
    Nov 17, 2011
    A 555 doesn't generate a sine wave, it produces square waves.

    I'd like to see how you did this. I've never seen this before. And I'm not that young anymore.

    Do you have any basic understanding of the workings of logic gates at all? Logic gates operate typically with well defined logic states, voltages near 0V of Vcc, but not -70mV. What sequence qre you talking about?

    It all depends where in the circuit these components are placed. Without you showing us your circuit, there is no telling.


    In all honesty, I doubt that you really understand what you are about to do. Take a good night's sleep, reset your brain circuit and restart from scratch. Start by describing exactly what you want to achieve. Then we may be able to find a suitable circuit.
    In my experience it is one of the worst things if you start with a circuit in mind and try to match it to your requirements. It's like standig in the kitchen with a hunk of 1A steak meat and trying o bake a cake from it.
     
  5. davenn

    davenn Moderator

    13,813
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    Sep 5, 2009
    Electro132

    in this thread and in your other thread on constant current power supplies
    you are showing a continues lack of wanting to learn real science/electronics

    Both these threads are on the verge of being closed unless you start demonstrating that you are doing something about learning the basic concepts of electronics

    continue the way you are presently going and you will find it even more difficult to get people to take you seriously and have any urge to help you

    as the old saying goes .... " the ball is in your court"

    Dave
     
    Last edited: Oct 17, 2013
  6. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    My mistake. It was the ICL 3038 component that does this.

    Well a science friend told me that if you connect a multimeter to the battery with switched leads (positive to negative and negative to positive) then you will get a minus displayed on the multimeter. This is due to the power coming out of the negative side of the battery since it is said that conventional current comes from the positive side.

    So if the leads were to be switched then the outcome value would be opposite of positive to positive and negative to negative


    ok forget about this, this is just confusing.

    Let's start this again. The objective is to reach - 70 mV in Direct wave form as an output.
    What i am trying to achieve is a starting point at - 70 mV.

    I've done some research and found these links to prove that it was looked at before.

    1) http://www.digikey.com/us/en/techzone/power/resources/articles/generating-negative-output.html


    2) http://www.ti.com/lit/ml/szzn001/szzn001.pdf

    3) http://www.societyofrobots.com/electronics_negative_voltages.shtml

    They should be able to help. I reckon the MAX232 IC should do the trick. Then i need to add the wave form.
     
  7. Harald Kapp

    Harald Kapp Moderator Moderator

    11,445
    2,628
    Nov 17, 2011
    That's a far way from converting a positive voltage to a negative voltage. It is the same voltage in both cases, by switching the leads of the multimeter you just measure with opposite polarity.

    The links you give link to techniques called "charge pump" or "switch mode". Both can generate a negative voltage from a positive voltage if suitably designed.

    Why would you use the MAX232? It is not intended for that purpose (also it can be abused to "do the trick"). Your links already point to suitable ICs. Or Google "charge pump negative output".
     
  8. Electro132

    Electro132

    261
    3
    Feb 12, 2013

    ok cool, so is it possible that we can build a circuit which does an output of -70 mV together?

    My only concern is that the DC line starts from 0 v and not from - 70 mV unless there is already an existing -70 mV presently generated by the Earth that i can just tune into and restrict until i reach - 70 mV. If not then this charge pump will do and we'll just go from there.
     
  9. davenn

    davenn Moderator

    13,813
    1,945
    Sep 5, 2009
    Together with what ?

    That just makes no sense at all

    you are going to start with a positive DC voltage from a battery or other power supply.
    You will use a converter chip like an ICL7660 to generate a negative voltage then you will have to bring that negative voltage down to your -70mV that you need.

    Dave
     
  10. Electro132

    Electro132

    261
    3
    Feb 12, 2013

    Thanks Dave. I'll look into it Cheers
     
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