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  • Jeffrey
    Jeffrey

    Member • Aug 12, 2013

    Capacitor as loading device

    What exactly is the loading effect of capacitor? I found this as one of the main applications of the capacitor in electronic circuits.

    The book pointed that the capacitor in the input of a transistor acts as a loading capacitor. How and what it loads and where does it load?

    Some insight in any form will be really helpful.
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Replies

  • pinank

    Member • Aug 22, 2013

    As per my knowledge capacitors are used as fillers in electronics!
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  • Jeffrey Arulraj

    Member • Aug 22, 2013

    You mean filters right Yeah I agree to filters

    But I found in a book that the capacitors are used to load in an electronic circuit

    I figured that it loads the input AC signal without any DC interference to the input of the Transistor or FET I am still not clear about this though
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  • pinank

    Member • Aug 22, 2013

    Ahh...no...they are primarily used as filters...either to filter out harmonics or as a lpf, hpf etc etc
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  • Jeffrey Arulraj

    Member • Aug 22, 2013

    pinank
    Ahh...no...they are primarily used as filters...either to filter out harmonics or as a lpf, hpf etc etc
    Yup true But David Bell states That capacitors serve 3 purpose
    • Filters
    • DC blockers
    • Loading circuits
    That gets me going over the heel to find what exactly is loading
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  • ABCD ABCD

    Member • Aug 22, 2013

    loading circuits? ... doesn't that mean it works as a load?
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  • Jeffrey Arulraj

    Member • Aug 22, 2013

    Well I am not sure load is connected in the input section of the circuit right
    mreccentric
    loading circuits? ... doesn't that mean it works as a load?

    Loading occurs in the input and not in the output side where we use a loading resistance to increase or decrease the output impedance
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  • pugazh anand

    Member • Aug 23, 2013

    Is ter any similarities btwn impedance matching & cap loading?
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  • Ramani Aswath

    Member • Aug 24, 2013

    Conqueror
    Well I am not sure load is connected in the input section of the circuit right
    Loading occurs in the input and not in the output side where we use a loading resistance to increase or decrease the output impedance
    A fully discharged capacitor can act as a DC load till it is fully charged. It has effectively zero resistance to start with. After this its equivalent resistance increases and it just blocks DC. It will let through AC signals.

    I am not sure if this behaviour is what is referred to by David Bell.
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  • pinank

    Member • Aug 24, 2013

    A.V.Ramani
    A fully discharged capacitor can act as a DC load till it is fully charged. It has effectively zero resistance to start with. After this its equivalent resistance increases and it just blocks DC. It will let through AC signals.

    I am not sure if this behaviour is what is referred to by David Bell.
    Sir but won't that be for a very small fraction of time..as the capacitor will charge up almost instantaneously(at least theoretically)
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  • Ramani Aswath

    Member • Aug 24, 2013

    pinank
    Sir but won't that be for a very small fraction of time..as the capacitor will charge up almost instantaneously(at least theoretically)
    You are right. Often that is all that is required.
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  • ABCD ABCD

    Member • Aug 26, 2013

    pinank
    Sir but won't that be for a very small fraction of time..as the capacitor will charge up almost instantaneously(at least theoretically)
    i counter this... It's not always a fraction of time. The rate of charging can be altered. So, i guess, it can be made so that the capacitor may act as a DC load for long time (in other words infinite time).
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  • Ramani Aswath

    Member • Aug 26, 2013

    mreccentric
    i counter this... It's not always a fraction of time. The rate of charging can be altered. So, i guess, it can be made so that the capacitor may act as a DC load for long time (in other words infinite time).
    Every capacitor has an RC value, which is a function for charging time. The R restricts the charging current. the total charge that can be held is decided by the C value. infinite time is possible only with infinite R. That is open circuit. Otherwise it is finite.
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  • pinank

    Member • Aug 26, 2013

    mreccentric
    i counter this... It's not always a fraction of time. The rate of charging can be altered. So, i guess, it can be made so that the capacitor may act as a DC load for long time (in other words infinite time).
    The capacitor will always tend to reach its steady state value ie once it is fully charged it acts as a open switch and the rate can be altered by changing the time constant value.. But at say time equals infinity it will eventually act as a open switch
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  • Ahsanul haque

    Member • Sep 3, 2013

    You mean filters right Yeah I agree to filters
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  • tanmoya

    Member • Sep 5, 2013

    capacitors prevents loading effect means...... 'loading effect' means short circuiting of input source. if the circuit has low input impedence then the circuit will draw maximum current and this will result on short circuiting of input source.
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  • Jeffrey Arulraj

    Member • Sep 6, 2013

    tanmoya
    capacitors prevents loading effect means...... 'loading effect' means short circuiting of input source. if the circuit has low input impedence then the circuit will draw maximum current and this will result on short circuiting of input source.
    Can you be more specific Cos How is the capacitor going to affect the impedance of the circuit

    Do you mean the DC impedance or the AC impedance
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  • tanmoya

    Member • Sep 6, 2013

    capacitor is obvious to be AC impedence.... it is used for coupling of input too...
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  • kumarrakeshit

    Member • Apr 29, 2014

    In my point of view capacitor just like to holding electricity of certain time period. And we can replace battery with capacitor.
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  • Jeffrey Arulraj

    Member • May 1, 2014

    But how does it affect the input of my circuit.

    What type of load does it provide to the input ciruit to which the capacitor is connected
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  • Ramani Aswath

    Member • May 1, 2014

    Is this of any use?

    #-Link-Snipped-#
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  • vamsi kancharla

    Member • May 1, 2014

    Jeffrey Samuel
    What exactly is the loading effect of capacitor? I found this as one of the main applications of the capacitor in electronic circuits.

    The book pointed that the capacitor in the input of a transistor acts as a loading capacitor. How and what it loads and where does it load?

    Some insight in any form will be really helpful.
    capacitors are also used for timming purpose in an electronic ckts
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  • kumarrakeshit

    Member • May 1, 2014

    Suppose if you are converting the ac to dc current then you must use the capacitor. then you can get desire output.

    I will search your question answer please give me some time. friend.
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  • pinank

    Member • Jun 12, 2014

    can this be the counter argument. Taking a simple circuit A BJt and AC signal is applied to its base. Now if there is no AC impedance, (CAPACITOR) the source will get Short circuited. And lead to damage of Bjt. Hence the capacitor would work as a loading device.
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  • Jeffrey Arulraj

    Member • Jun 13, 2014

    Source has some reactive impedance so I am not sure what you are implying

    Can you pls post a little schematic here to explain the scenario little more clearly?

    And Load is generally at the output side and the trans impedance effect of it on the input source is really less in case of Semi conductors right
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  • pinank

    Member • Jun 13, 2014

    Jeffrey Samuel
    Source has some reactive impedance so I am not sure what you are implying

    Can you pls post a little schematic here to explain the scenario little more clearly?

    And Load is generally at the output side and the trans impedance effect of it on the input source is really less in case of Semi conductors right
    Yeah u r pretty much right..I got it all wrong.. :/
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