Up/Down Timer For A Power Antenna


Posted on Feb 6, 2014

This up/down timer was designed to control a power antenna on a late-model vehicle. Normally, this vehicle uses a body computer to control the antenna. However, the person who owned the vehicle wanted to install his own high-powered audio stereo system. The original stereo system was tied in with the body computer and this meant that a separate an


Up/Down Timer For A Power Antenna
Click here to download the full size of the above Circuit.

tenna controller was required for the after-market sound system. Also, the power antenna fitted did not have limit switches inside, hence the need for a timed control circuit. Here`s how the circuit works. first, assume that the radio antenna control output is not switched on - ie, the radio is switched off. In that case, relay RLYC will be off and so relay RLYA will also be off, as is the motor. Conversely, when the radio is switched on, the radio antenna control output line switches to +12V. And when that happens, RLYC closes its contacts and applies power to the circuit. As a result, C2 (330OF) quickly charges via D4, while Q4 is biased on via D5 and R5. This ensures that Q3 and relay RLYB remain off. At the same time, Q2 is is turned on, thus turning on RLYA and applying power to the motor. This drives the antenna in the up direction. During this time, C1 charges via R2. When the voltage across the capacitor reaches +8. 1V, Q1 turns on via ZD1 and so Q2 turns off and switches off the relay - ie, this gives the "up" timeout. Using the values shown for C1, R2 and ZD1 gives an "up" duration of approximately 6 seconds - long enough to fully extend the antenna. D1 discharges C1 (via resistor R1) when the +12V supply is later removed. When the radio is switched off (or a CD placed into the stereo unit), the radio antenna control output switches back to 0V. This does several things: first, it turns Q4 off and this allows Q3 to...




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    120 and 240Vac LED Indicator
    Biomedical Monitoring circuit AT89C2051
    Scrolling text in LED dotmatrix display
    Basic RF Oscillator circuit diagram
    arduino uno schematic
    a simple electrocardiogram board
    tda2040 car stereo amplifier circuit
    Fun with LEDs
    charge monitor for 12V car battery circuit diagram
    Regulator circuit silicon resistor formed
    Using kd-28 to do the voice switch circuit diagram
    Binary counter circuit diagram



    Top