I have this setup which is a part of a bigger circuit to control motors.
This is supposed to be a timer in monostable mode with about a minute of hi output when triggered.
The lines going down are to give the Q2 base high and Q4 to turn the timer off when the downward lines are high but when they are low the timer should trigger and start giving out high.
I tried randomly to put a switch between R12 and ground and that helped trigger the device. So I would in theory turn the device on and then turn on the button to trigger this timer.
I don't quite understand why it won't trigger when this bottom common line is low.
Should it be dragging the base of Q2PNP down to open it which would then add voltage to the base of Q3 NPN which would drag the trigger of the timer down?
The setup of the C2 and R2 is so that the output time won't be affected by the input staying low so the output time is always the same as this capacitor and resistor pulls it up.
I want it to just
- Device ON
- Trigger low
- Output Hi
- until trigger is reset by Q4 or time is up.
Am I missing something here?
Uploading the full schematic just for a better understanding.
Currently, the rest of the schematic works fine in simulation except the part I posted originally.
I have a counter to count button clicks.
Once a button clicks a 555 timer for backwards goes high, and once it drops from high to low it triggers the 555 timer for turning.
Both backwards and turning timers give out high into the forward 555 timer to make sure that one isnt giving out high.
I just need the forward timer to start off as high and get deactivated by the other timers but once they go back to low that forward will be activated once again.
Using a PNP transistor as a switch is a mess and a half.
I just realized that the whole point of C2 and R2 was for the trigger event to only trigger once so it wouldn't affect the output time, but on this specific timer the output is allowed to be high as long as it can.