I have a power device that controls three circuits: one siren, and two electric DC motors.
At prototype level and software development everything works fine since one year.
I face now the final design of the whole system.
My idea is to design two PCBs with Fritzing and order the final design PCBs from a well known specialist.
In the signal stage PCB I will place ATMega 328PU, HC-05 BT device, crystal, capacitors and all the logic control components,
In the power stage I will place the three MosFets, flywheel diodes, solar battery charger ICs, protections and so on.
I will electrically isolate signal stage from power stage using optocouplers.
My question is to know which is "best practice":
To place the optocouplers in the output section of the signal stage or
To place them in the input section of the power stage.
Thanks for your guidance in this matter,
Kind regards,
Horacio
Using a few different power stages, drivers, having the opto coupling on their boards I have not experienced any trouble. Looks like good practise to keep the power stuff at good distance from the logics.
I use Adobe Eagle (free) to draw schematics and layout boards. Eagle generates the files needed by the PCB maker (I like JLCPCB). JLCPCB will make your boards (5 boards for $2) and ship them usually within 24 hours. Unfortunately, U.S. Customs inspection takes three or four weeks to clear.
Some things I learned from experience and friends:
Don't put logic lines too close to power lines/component. This is especially true if you have noise generating components like motors.
90 degree, right angle turns are bad. Use 45 degree turns and if possible, rounded 90/45 degree turns.
If possible, use ground planes.
Make power and ground traces wider.
NEVER rely on Autorouter
aarg:
You can stop right there. Wrong tool.
Seconding this. Fritzing is not good for anything other than simple pictures. Adobe Eagle has a free version, and is an excellent tool. EasyEDA is also an OK tool that can be accessed on web.