Originally Posted by
GerryH
That's probably why it didn't work on one of my motors. It's output voltage was very low when triggered. Didn't think about a pullup resistor. I'm still learning.
What would you use to control the transistors? A 555 timer?
I would wire the sensor LEDs to the 5V rail, use a 470ohm resistor on them to limit the current less than 10mA (worse case red led with 1.8V forward voltage should be around 7mA). The open collector output of hall sensor can sink some current, that is the idea, but they can't sink a lot.
I think what
Roelof is suggesting is using an invertor as a buffer. When the output goes low the inverter will source to the open collector. and then output a 1, which will be pulled low by the LED and resistor. Again, these inverters are not high current devices so I would use a 470ohm resistor instead of the 220ohm you are using since two LEDs can be on at a time.
No need for a timer, this system isn't going going to have logic races, so no need to clock the inputs.