need help with the no code circuit design

[coolMango]

I’m building a super compact circuit (must fit inside a 15mm cylinder) and I have zero programming experience, so I’m hunting for off the shelf parts.
my setup is power: 3.7v 500mAh LiPo, load: 3.7v Highspeed DC Motor (40k RPM).

I need the motor to kick on at instant full power, but only after I remove an external magnet. I also need a variable timer (via a small pot) so it runs for somewhere between 10–25 seconds before shutting off. Placing the magnet back should reset the whole thing.
Since space is so tight, does anyone know of a tiny, premade timer relay or a simple way to wire this up without a microcontroller?
A clear diagram or part list would be a lifesaver!

 

[theOhmcoder]

Messed around with something like that for a motor thing last year. I just used a little 555 timer chip and a MOSFET. It was small enough and switched on right away no problem.

 

[capacitorkid]

Built a compact motor trigger for a model project once. Combined a latching relay with a small adjustable timer IC. Wasn’t pretty, but it fit perfectly and worked just as you described.

 

[Tovaren]

In a previous cylinder project I skipped programming by using a mini delay relay and a hall effect sensor.
This setup allowed me to turn on the motor right when the magnet moved and controlled runtime with a small pot.

 

[barfle]

555 timers are pretty foolproof and pretty small. Reed relays are also very small, and probably would work for your magnetic switch if you can’t find just the core.

 

[theOhmcoder]

555 timers are pretty foolproof and pretty small. Reed relays are also very small, and probably would work for your magnetic switch if you can’t find just the core.

Absolutely, 555 timers are really dependable, and using reed relays would work great for that magnetic switch config.

 

[capacitorkid]

That makes sense. 555 timers and reed relays are small and reliable, so they're great for a setup where space is tight