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    Fixed voltage Positive and Negative regulator ICs are used in circuits to give precise regulated voltage. 78 XX series regulator IC can handle maximum 1 ampere current. The Regulator ICs require minimum 1.5 higher input voltage than their voltage rating. For example 7805 IC requires minimum 6.5 volts to give 5 volt output. Here are some circuit designs of IC 7805 to monitor the output voltage.

    1.This is the manipulation of the Regulator IC 7805 to give 9 volt regulated output. Normally the pin2 of the regulator IC is connected to the ground. Here it is connected to a 3.9 volt Zener diode. So the output from the Regulator IC will be 9 volts.

    7805 Circuit 1

    2. This circuit can tell whether the IC 7805 is giving output or not. IC 7805 requires minimum 6.5 volt input to give 5 volt regulated output. When the input voltage is above 6.5 volts, Zener conducts and LED turns on indicating sufficient input voltage. Diffuse type Red LED requires 1.8 volts and Zener 4.7 volts .So to activate both these, input voltage should be minimum 6.5 volts. If the input voltage drops below 6.5 volts, Zener cutoff and LED turns off. This indicates the zero output from the regulator IC.

    7805 Circuit 2

    3. This is a simple LED monitor to tell the output voltage from 7805. If the input voltage is above 6.5 volts, LED shows full brightness. When the input voltage reduces below 6.5 volts, brightness of LED decreases.

    7805 Circuit 3

    attentionThe author D Mohankumar is not an active member anymore. Please take into consideration that the presented information might not be correct.
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    10 Responses to "7805 Regulator IC Circuits"

    1. in ckt 1 , is it possible to get an output 14v by adding another zener diode in series with the first zener and by supplying input of 13-16V.

    2. Hi!
      I think it may b possible., And I have one question., If it is possible., then we can obtain any voltage by giving many zeners in series , can’t we..??

    3. “78 XX series regulator IC can handle maximum 1 ampere current. ”

      If you use a ST Microelectronics made “78xxCV”, they can support 1.5A continuous instead of the regular 1A ones.

    4. linear regulatorz are good but they result in too much loss and also very big. mcp1700 are smaller.
      i would prefer switch regulators more. very less loss :)

    5. 78XX What is the indications of 7,8

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