I want to turn my tactile momentary switch in to a on on/off off switch. I found this tutorial here http://www.instructables.com/id/Use-a-Momentary-or-Tactile-Switch-as-a-Pushbutton-/ But its as clear as mud, especially for a beginner like me.

I have a little 1.5V motor that I want to be able to turn on and off with one push. and I have to keep all components small so they will fit into a small ikea train block or matchbox. So i am basically looking for a tutorial online with some clear and simple instructions. Any constructive advice is very welcome.

 

If the electronics is to run from 1.5V then that severely restricts your options.
How much current does the motor need?

 

You use the tactile switch to trigger a Type D Flip Flop. One Push ON and another Push Off. The output drives a small transistor to drive your little motor. Without knowing the motor current that is about as good as I can guess. There isn't much to it.

<EDIT> I see Albert beat me to it and yes, the 1.5 volts limits things. </EDIT>

Ron

 

You use the tactile switch to trigger a Type D Flip Flop.

Is there a 'D' type that will work on 1.5V (and presumably lower voltage than that as the battery discharges).

 

Is there a 'D' type that will work on 1.5V (and presumably lower voltage than that as the battery discharges).

The best I see would be a CMOS and the minimum would be 3.0 volts. Even with a 3 volt motor a brush type motor will wreak havoc with the flip flop and exactly as you mention, soon as battery voltage drops it will get erratic. Really I don't see a 1.5 volt solution, let alone a simple one.

Ron

 

An old style transistor bistable might work (with schottky diodes).
[Edit] There are (still!) some germanium transistors and diodes on ebay which would make it easier.

 

An old style transistor bistable might work (with schottky diodes).
[Edit] There are (still!) some germanium transistors and diodes on ebay which would make it easier.

I really don't know. Sort of funny as it is one of those things I never really thought about or actually had to think about. The more I think about that 1.5 volts and as soon as that drops the more problems I potentially see.

Ron

 

If the electronics is to run from 1.5V then that severely restricts your options.
How much current does the motor need?

 

If the electronics is to run from 1.5V then that severely restricts your options.
How much current does the motor need?

The motor I found is tiny and runs on 3-1volt
https://m.dhgate.com/product/micro-...ry_sellerconfirm_2017|browse1|20170415#pd-011

 

This circuit works down to 1V supply in the simulator. Will need the transistors on the left sorted to suit the motor current (R8 represents the motor).

 

If you can run with 3 volts using a CMOS Type D Flip Flop may work. I was looking at the CD4013 which is a dual D flip flop and according to the data sheet should work with 3 volts. I am just not sure how well the chip will work or if motor noise will effect the chip's operation. Albert mentioned another good option which is build a D flip flop circuit using transistors.

Hopefully we will get more input as I don't want to suggest you build a circuit that won't work.

Never mind, I see Albert was busy. I would run with that circuit.

Ron

 

What you need is a bistable circuit. Something such as this:

 

Just thought of another problem - switch bounce

 

They make toggle type tactile switches. It won't care about 1.5 volts, it's a switch. Will handle about 500mA which is more than enough for your motor. Where's the fun in that? None, except it is small, can be directly wired, no circuit board to fidget with. I think this is simply a small toy that is being motorized switch+battery+motor. ADAFRUIT-ON-OFF power switch. It's 12mm square and 6mm high. No way you can beat that with a tactile switch on a PCB and a bunch of components, unless one was going to go all SMD components. Sorry, but not much application for a cute electronics circuit in this instance.