Newbie - Minimum necessary to control RC servo & 1 relay

You may want to check the comp.robotics.misc news groups for similar setups. I don't understand how you are sending IR through a serial port, but a simple way to control servos from a computer via the serial port is to use a programmed servo control chip. At the link below I show how I use the ezservo chip from kronos robotics ($6.95) to control servos that operate a pan and tilt webcam. The bottom link shows a workaround I made to control some LEDs using the servo control output lines from the chip. This could control a relay if desired.

shb*NO*SPAM*@comporium.net (Si Ballenger) wrote in news: snipped-for-privacy@news.comporium.net:

I meant a PC serial port connected to an IR transmitter.

Thanks. That is just what I was looking for. I thought there'd be a chip for that app.

Where's the circuit that converts a servo output to an on-off output?

Ben

For the LED I put a diode and a 1k resistor in series from a servo output pin to the base of an NPN transistor. Between the diode and the resistor, I put a .1mf capacitor connected to ground. There are sufficient pulses for the servo (chip set for its longest pulse lenth on the pin) to charge up the capicator and supply a ~steady current to the transistor base. The LED is connected to a power supply and is in series with the transistor collector/emitter. A driver chip that needs less current to turn on might work better than just a NPN transistor in this setup. YMMV.