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Older Toyota OEM radios use 2 wires to extend and retract the antenna: when the antenna is to go up, one wire is Vcc and the other is GND. After a certain number of seconds, the two wires are either floating or GND (not sure which) and the antenna stays up. When the antenna is to go down, the two wires switch polarities for a number of seconds before returning to float or GND.
Generic extendable antennae like the Metra brand use 3 wires: power from ignition, GND, and a "control wire." The control wire: maintains Vcc when the antenna is to raise and stay up, then go to GND or float when the antenna is to retract. In other words, the control wire is held at Vcc when the radio is on.
This circuit, basically a latch, is intended to convert from the OEM Toyota wiring to the generic extendable antenna wiring. It takes as input Vcc from the ignition, GND, and the two original OEM antenna wires. The upper switch emulates the OEM antenna wire which receives Vcc when the antenna should raise up. The lower switch emulates the OEM antenna wire which receives Vcc when the antenna should lower down. In this simulator the switches switch to GND when off but, since I don't know if the Toyota wiring goes to GND or float, this circuit works if the "off" position is float instead of GND as well.
A 5th wire, the output wire, is emulated by the load in this simulator. It attaches to the control wire of the generic antenna.
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