I am trying to build a small v-reg module for a bot I'm building. The reg board needs to provide 12V @~1A for a H-bridge, 5V~.5A for the steering h-bridge and 5V @~150mA for the micro and other digital. I have sort of made up a battery pack consisting of rechargeable nicad AA's (1.2V @600mA) wired in series to make up ~14V and in parallel to double the current. I am not by any means a formally trained designer, so I have been going through alot of crap trying to figure out the best way to implement this spec. So far I have changed the design at least 5 times- now its just getting stupid...I seem to be over-thinking every part of it, which is good in a sense because I really do need to be able to do the calculations and proper design techniques, so all of the 'floundering' has not been a total waste....
What I have at his point is a small 20x53mm pcb, 1 sided with a couple of jumpers on the other side. The battery pack leads run into the pcb through a 4001 diode and a filtering cap (~470uF 25V) onto two v-regs. The first is 12V 1A and the second is the 5V 150mA. Each have respective 0.1uF caps attached to both in and outputs and also an indicator LED run through resistor and to gnd. The voltage drop for the additional 5V @~500mA will be provided by a divider from a parallel trace from the 12V vreg output. I have been having alot of problems finding the right resistors to make up the required spec- I can find the voltage fine but the current gets pintched out so much the motor doesn't move at all and I get no reading/minute results on the multi-meter. I'm wondering is it better to do a voltage divide using diodes rather than resisitors? what is the difference? does one regulate current better than another? Finally I am wondering if I am doing something dead wrong here.
I would post a schematic but I didn't draw one up on the CAD- just paper scribbles., only have the attempted layouts on the CAD and I'm too 'ashamed' to post em,.--One particular aspect which has been causing me lots of concern is the gnd network. The overall design will be modular- in that each 'functional ' block will be on its own small PCB. I've tried to break them down as simply as possible- the batt charge module runs into the reg module which splits off to respective H-bridge PCB's, motor(s) feedback PCB, uC mainboard and sensor modules. Some of these boards are plainly analog while others may be a mix and some just digital. I have tried to keep the analog portions all running from the 12V reg outputs and the digital only from the 5V 150mA reg. The problem I am having is that they all share a common ground due to the config of the regulator module--and I am wondering if this is a setup to failure, what some things I can do to help this possible situation without a complete re-do, etc.
Please any advice is more than welcomed, heckling, tips etc....thanks in advance, jd
PS- I had to completely re-register to post today,, I forgot my password, tried to get a temp issued but the server didn't ever send one! I tried a few times too! geez....
What I have at his point is a small 20x53mm pcb, 1 sided with a couple of jumpers on the other side. The battery pack leads run into the pcb through a 4001 diode and a filtering cap (~470uF 25V) onto two v-regs. The first is 12V 1A and the second is the 5V 150mA. Each have respective 0.1uF caps attached to both in and outputs and also an indicator LED run through resistor and to gnd. The voltage drop for the additional 5V @~500mA will be provided by a divider from a parallel trace from the 12V vreg output. I have been having alot of problems finding the right resistors to make up the required spec- I can find the voltage fine but the current gets pintched out so much the motor doesn't move at all and I get no reading/minute results on the multi-meter. I'm wondering is it better to do a voltage divide using diodes rather than resisitors? what is the difference? does one regulate current better than another? Finally I am wondering if I am doing something dead wrong here.
I would post a schematic but I didn't draw one up on the CAD- just paper scribbles., only have the attempted layouts on the CAD and I'm too 'ashamed' to post em,.--One particular aspect which has been causing me lots of concern is the gnd network. The overall design will be modular- in that each 'functional ' block will be on its own small PCB. I've tried to break them down as simply as possible- the batt charge module runs into the reg module which splits off to respective H-bridge PCB's, motor(s) feedback PCB, uC mainboard and sensor modules. Some of these boards are plainly analog while others may be a mix and some just digital. I have tried to keep the analog portions all running from the 12V reg outputs and the digital only from the 5V 150mA reg. The problem I am having is that they all share a common ground due to the config of the regulator module--and I am wondering if this is a setup to failure, what some things I can do to help this possible situation without a complete re-do, etc.
Please any advice is more than welcomed, heckling, tips etc....thanks in advance, jd
PS- I had to completely re-register to post today,, I forgot my password, tried to get a temp issued but the server didn't ever send one! I tried a few times too! geez....