Ban said:
There are a few design flaws in your work, did you really pass that class?
Yes, I did well. This was for an introductory class.
Worst is the transmitter stage The current through the LEDs is only
determined by their forward voltage it can vary a lot and will degrade
performance since the max. permissable current is surpassed.
The forward voltage did not vary all that much since it is set by the
current through V_cc / (R_9 + R_10). However, I have allowed ample room
for variance, taking into account the 50% duty cycle.
Your calculation "current sourcing" is completely wrong. The LEDs are in the
collector line and do not contribute to the Vbe calculation.
You are right. Should be as I stated above. Thank you for bringing the
error to my attention.
The transmitter will have big noise problems, as you amplify any ripple on
the supply voltage through your bias resistors,
The supply is quite stable, but yes I see your point. Noise could
potentially be a problem in a particularly noisy environment.
some of which can be omitted...
Yes, R10 can be omitted, and R9 doubled to have a near equivalent
effect.
Cheers,
Chris