# Inverted 555 Monostable Timer With a Sustained Input

I am using a 555 Timer to control a motor for a science team project. I have to make a Rube Goldberg-like machine and I am not allowed to use Arduinos or Raspberry Pis. However I need to trigger the motor and then have it turn off by itself, after a set amount of time. I have been trying to do this with a 555 timer and have had a little luck, but not a ton. So any help in figuring this out (maybe a circuit diagram) would be appreciated.

I want to motor to trigger for about 8 seconds (I know how to do the resistance calculations and figure out the size to use, so this can be worked out later) when I close a circuit/create a high signal. To do this, I have been using an inverted 555 set up, which lets me use a high voltage as a trigger. However, I cannot figure out how to either make this behave as a pulse, maybe using a capacitor, or to configure the 555 timer to use the start of a high signal as the start of the timer.

Really, I just want to know if there is a way to make a sustained signal behave as a pulse for a 555 timer, possible with capacitors, and how to do it.

Thanks!

Edit:

Specifications: Just a small motor DC circuit motor (I forget what the specifications are, but easily battery powered), 4 AA batteries in series. Other than that, it's your standard series circuit. I can use some small microcontrollers or ICs.

• does "no Pi and no arduino" exclude other microcontrollers as well? because, this sounds much easier with something designed to you know, be small and control stuff. Like a microcontroller. Jan 6, 2019 at 23:36
• What motor? We have zero idea how much current is required to operate the motor (or should we take it as given that the 555 is adequate?) and no idea what voltage is required. Way, way too little information to be much help. Can you improve your question?
– jonk
Jan 6, 2019 at 23:39
• You should provide more info about the rest of the circuit, source, load, electronic switch, mechanical input switch(MCPB?). This is indeed an easy circuit to execute with a 555 monostable or two.
– K H
Jan 6, 2019 at 23:59
• Possible duplicate of Easiest way to extend a pulse or edge sensitive non-retriggerable one-shot electronics.stackexchange.com/… or electronics.stackexchange.com/… Jan 7, 2019 at 0:22
• What do you mean by "Inverted Mode" ? Jan 7, 2019 at 1:39