Hi,
My thoughts:
- Yes the 100 nf is required at the IC (as close to the Vcc, Vss pins as possible. The 10µf on each board is helpful as well.
Note the exact value is not critical.
2a) Resistor value must be determined by how much current needs to be diverted from the LED's. I would start with 500k then 100k.... etc.
Keep in mind the power in the resistor is:
- P = E^2/R
- P = 200 * 200 /R
- P = 40,000/R
FOr reference, 100k ohm resistor will dissipate 0.4 watts you must purchase at least a 2 W or better yet a 5 W resistor.
You might try something greater than 500k and maybe get the LED brightness down to an acceptable lever without it going completely off.