max232 - Circuitos electrónicos

http://pinouts.ru/Converters/rs232-TTL_cable_pinout.shtml

http://dangerousprototypes.com/blog/2016/05/17/butchered-usb-ttl-serial-adaptor

http://bbs.dapj.com/2006/07/isolated-rs232-interface-to.html

https://electgpl.blogspot.com.ar/search/label/Conversor USB UART TTL

https://joey89924.blogspot.com.es/search/label/TTL

https://radikaldesig.blogspot.com/2008/05/power-booster-para-puerto-serie.html

http://robots-argentina.com.ar/Comunicacion_InterfazRS232.htm

https://txapuzas.blogspot.com/2009/12/paperrs232-convertidor-rs232-ttl-para.html

http://www.datasheetcatalog.com/catalog/p749040.shtml

http://www.qsl.net/eb4eqa/serial_booster/serial_booster.htm

http://www.seattlerobotics.org/encoder/aug97/cable.html

http://www.superrobotica.com/S320112.htm

http://circuitdigest.com/microcontroller-projects/gsm-module-interfacing-with-8051-at89s52

http://www.rfcandy.biz/communication/trinity.html

http://dangerousprototypes.com/blog/tag/max232