My first bot (in 70% complete build state) has many different power supply needs listed at end. Most things run off lead acid 12v bus battery with linear regulators(problems there). While that and a smaller 12v lead acid battery in series supply drive power and 2 sensors.
First question is such an unbalanced system safe and practical? My only battery charger is a single 12v Schumacher SC-6000A which I apply alternately to each battery in turn without disconnecting anything, often while parts of the bot are still operating (for example the computer I am typing this on right now.)
Second, I made a perfboard with LM317t R1=220 R2=1k C1=0.1uF on input, no output cap for 7v microcontroller supply(works). On the same board with parallel 12v input is a 7805 regulator with no caps(never worked). I verified no solder bridges, 12v and ground is present at 7805 pins but no output (actually fluctuating voltage around 200mV). I tried 3 different 7805 chips. Load for test is a 6v 25mA lamp. Could the other regulator somehow interfere with the 7805? Do I really need to add caps? Is there a better way to do this? The speed controller provides a 10ma 5V regulated output is there a way to boost this with a transistor? I am still learning electronics. For the 4.5v for GPS I planned to simply insert a diode in the 5v supply to drop .7v. Does anyone know what specs the rino serial interface is? The stock cable is a 9 pin PC serial but I find it hard to believe it is RS-232 +/-15v from 3 AA batteries. I had to build a custom cable to provide power at the same time as communication. I don't have an oscilloscope.
24v 15A each for 2 wheelchair motors(Dimension engineering sabertooth 2x25), 18-30v 4w for 2 ultrasonic sensors, 6-24v 125w computer supply(M3 from logic supply) 10-30v for Omron photoelectric switch and capacitive proximity sensor, 12v nominal for LCD monitor 3A, wireless router 12v 1A, pyrosensor 9v nominal, 7v for microcontroller (currently Vex, may change to Axon, Arduino, or other), 5V for 4line serial LCD display, DE 3 axis analog accelerometer, plus other sensors, logic switches, LEDs, etc, 4.5v MAX for Garmin rino GPS/FRS radio