Project: Time delay switch for mobile chargers:

Discussion in 'The Completed Projects Collection' started by dileepchacko, Aug 13, 2008.

  1. dileepchacko

    Thread Starter Active Member

    May 13, 2008
    102
    1
    Dear All

    Here is useful project.
    Time delay switch for mobile chargers:

    Most of the mobile phone batteries can be fully charged within 2 Hours of time. This circuit is useful especially night time. Before going for sleep, we can put the charger on and go for sleep. Don t worry about over charging, this circuit will switch off the charger after 2 Hour. This is a simple monostable multi vibrator, which will switch on the circuit for a particular time period. When the circuit is in standby mode, transistor Q1 does not conduct, since its base is floating. When the switch( SW1 ) is pressed and current flows through R5 and the switch to provide positive bias to transistor Q1. Transistor Q1 conducts and its collector voltage drops, which acts as a negative trigger input for the monostable. Here a pulse will be generated 7200 second duration ( 2 hour ). See the
    attachment.
     
  2. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Hi,

    Current cell phones can be left on charge without detriment, since they contain a complete charge control system.

    Not having an automatic system in the phones would be dangerous, as most use lithium batteries.
     
  3. mgksmoke

    New Member

    Oct 10, 2008
    1
    0
    This would be useful though for some dumb chargers such as those used on some commercial hand held radios.
     
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