I have build up a simple circuit with HD44780(LCD), L293B and 4x this motors:http://www.robotshop.com/world/dfrobot-6v-180-rpm-micro-dc-geared-motor-with-back-shaft.html, powered at 5V. With a only 1 motor connected it works great, but when I connect 2 or more motors everything go mad (whole circuit starts reset itself, LCD print strange marks and words, motors works how they want to). A current draw looks fine (250mA per 1 motor); L293B is powered externally and there should be no short circuit. I tried to add 100nF capacitor between Vcc1 and GND (internal logic) and 1000uF between Vcc2 and GND (motor supply). Maybe a very little progress here, but still it not working. Does anybody know, what should be wrong with it, please?