The 1.5V comes from a single AAA battery cell (not shown)
Here is the datasheet for the NOR chip CD74AC02: http://focus.ti.com/lit/ds/symlink/cd74ac02.pdf
-- it works with Vcc from 1.5->5V
The LED in the NTE3086 has a typical voltage of 1.1V @ 20mA. And the VCE
saturation voltage is 0.2-0.4V at 16mA for IF
, so well within the 1.5V supply voltage.
These being the only IC's in the circuit (this is just a splitter device, to replicate from 2 outputs to 8 - I'm only showing 2 outputs for simplicity's sake), should have no issue running from a single AAA cell. My only real concern is the value of R1/2 being too high to register a proper high signal at IC1x - that's easy to solve by reducing the value though.
I want the C+Es on the outputs to be in the exact same state as the C+E's on the input. I just want to replicate the status of the two outputs into 8 outputs.
The function table for the NOR indicates that if either input is HIGH, it outputs a LOW signal - this means that in drawing 1, by default it is outputting a LOW signal when OK1/1's LED is not engaged, because the OK1/1's Collector is pulled HIGH. Thus, when LED OK1/1 is off, the following is the state of the function table:
IN1 IN2 OUT
H L* L
* IN2 is tied to GND, so is always low. If that is the case, and the output of the NOR is connected to the cathode with the anode tied directly to 1.5V, would that not result in the LED being on on OK2/1 when OK1/1's LED is off? (I.e. allowing voltage to flow from A to K because K is biased low?)
I can't seem to figure out how I've gotten that wrong? Is that not the function of an NOR, and is that not the state of the IC1C when OK1/1 LED is not engaged? Or is the pull-up too weak?
Your table #1 also seems to be wrong to me (it presumes an inverter when I have an NOR):
-----LED OK1 TRANS -----INV----- LED OK2 TRANS -----
hi on on lo hi off off hi
It should be:
-----LED OK1 TRANS -----NOR----- LED OK2 TRANS -----
hi on on lo hi off off off
Even simplifying it to use an inverter like below, we still have the cathode low on OK2/1 when the base is NOT energized on OK1/1 - as the input is pulled high by default, thus would not the LED on OK2/1 be energized in this state, and therefor energizing the base on OK2/1, resulting in an inverted state between the input and the output?
I'm pretty thoroughly convinced that I can make it work now, with an NOR connected between the anode and the collector.
To be honest though, I'm starting to think there isn't a need for either an NOR nor an inverter! The following seems to make perfect sense to me:
It seems like I've made things way over-complicated and just confused myself along the process, if what I said earlier holds true, then this must also - given that I can completely prevent the anode from ever being pulled to 0V, it should never have a reverse current condition?