Hi again folks, been busy farting away on this project for last day or so- managed to get uC mainboard done yesterday and this morning am looking to put the main h-bridge together. If anyone here has seen my other two posts, the first has details regarding the design, but I'll quickly go back over them here:
The main (rear motor) h-bridge design is typical for the most part (please check out attach and focus on left side H only). The H bridge itself was basically copied from the radioshack PCB which occupied the platform I am targeting. I have seen varieties of this design all over the internet in the past,, the part which is starting to bother me right now is the small transistor that switches a pair of larger opposing transistors. The original uses SS9014, mine the 2N3904, both of fairly similar values to switch the large pairs- in my particular implementation I would like to isolate the uC from the H(s) so want to use some photocouplers I have salvaged from old modems (PC817). I've never tried using them before,.have checked out the sheet and some other projects which used them but in my case still am unsure about implementation due to the small transistors in place already- in this case would I be right to cut out the small signal transistor(s) and replace with photocoupler transistor(s) respectively?
How about connections driving from uC? low or high side, I thought low? Would be easier to layout also based on my existing design/layout scribbles.
Any tips with this would be great, have other portions to work on as well but this is what I wanted to build today, thanks in advance folks! jd
The main (rear motor) h-bridge design is typical for the most part (please check out attach and focus on left side H only). The H bridge itself was basically copied from the radioshack PCB which occupied the platform I am targeting. I have seen varieties of this design all over the internet in the past,, the part which is starting to bother me right now is the small transistor that switches a pair of larger opposing transistors. The original uses SS9014, mine the 2N3904, both of fairly similar values to switch the large pairs- in my particular implementation I would like to isolate the uC from the H(s) so want to use some photocouplers I have salvaged from old modems (PC817). I've never tried using them before,.have checked out the sheet and some other projects which used them but in my case still am unsure about implementation due to the small transistors in place already- in this case would I be right to cut out the small signal transistor(s) and replace with photocoupler transistor(s) respectively?
How about connections driving from uC? low or high side, I thought low? Would be easier to layout also based on my existing design/layout scribbles.
Any tips with this would be great, have other portions to work on as well but this is what I wanted to build today, thanks in advance folks! jd
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