This one is actually serial port relay circuit.
Image source:
http://www.rentron.com/pc-relay.htmThis circuit needs well regulated +5V power to operate. It can come from external power supply or from
inside PC. You can get +5V power from PC from the following ports on PC case:
- joystick port (up to several hundred mA)
- USB port (up to 100 mA just wiring + and ground wires).
- mouse/keyboard connector (up to 200-300 mA I think)
Please let me know if you know about sample like this with USB
and the Relay is power up from the USB
You can connect serial port driven relay controlling circuit to USB port with USB-RS-232 adapter.
Image source:
http://www.ftdichip.com/You can get power to your circuit from another USB port with a custom cable you make, one that
connects +5V (pin 1 in USB connector, typically red wire inside USB cable) and ground
(pin 4 in USB connector, typically black wire inside US cable) to your circuit needing that power.
[img]http://www.geocities.com/k7hkl_arv/PC_USB_Connectors_Pinout.png/img]
Image source:
http://www.geocities.com/k7hkl_arv/PC_U ... Pinout.png
Image source:
http://www.riccibitti.com/pc_therm/USB_A_pinout.jpg
Image source:
http://www.interfacebus.com/usb-cable-diagram.gifOther ideas could be to use some of the adapter cables and/or modules from FTDI
http://www.ftdichip.com/ They have for example this cable
http://www.ftdichip.com/Products/Evalua ... L-232R.htm that can give out from the same connector serial data (TTL level) and +5V out from the same output
connector that can plug to your own circuits.
Image source:
http://www.ftdichip.com/
