What is the simplest way to connect a small 6-12V DC motor to 230V UK mains supply?
Power supply 12 volts 2 amp.
This wall wart under $4 at
runs off 100-240 VAC 50/60Hz...
Is the simplest way to connect a motor to 12VDC @ 2A....
Find a power converter (also called "AC adapter", "power supply", and other names)
that converts 230 V AC mains to 12 V DC. That's the first thing.
The second thing is, when shopping for this 12 V DC adapter, to pick one with a current rating (i.e. the maximum current it can supply, in amperes (A)) greater than the current that will be drawn by your motor.
The third thing, I guess, is if you want some way to sort of throttle power to the motor, for to adjust its speed, there are a couple of ways to do this.
One way is to just use an AC adapter with lower voltage output; i.e use one with 9 V DC out, or 6 V DC, instead of the full 12.
A second way is to put a rheostat (a variable resistor) with resistance roughly the same resistance, and power rating, as the motor itself. The advantage of the rheostat is it is physically simple. The disadvantage is it wastes power, and needs to dissipate that power as heat. For example, even when the motor is being run at 10 percent power, the motor and rheostat together, are still using as approximately as much power as the motor would be running at 100 percent power.
A third way, is to use some kind of DC-to-DC converter, or PWM (pulse width modulation) module, to sort turn the motor off and on, in very small slices of time. The advantage to using a module of this kind is power efficient. The only disadvantage is the module that does it is complicated.
However, the complicatedness is not a big deal, if you can find someone else to build the module for you, and build it cheap. And it turns out, that this has already happened. Today, there are inexpensive DC-to-DC converter modules, and even modules designed specifically for driving electric motors.
I guess then the complicated part is picking a module that is right for your motor.
The related panel, on the right there, seems to be showing us a bunch of Arduino stuff, but it turns out there are more simple things. Like a DC-to-DC PWM module with just one knob to turn, and with that knob, or screw, located on the module board itself. These exist, and you find find them sold on eBay. Usually it is the Chinese sellers who have the best prices, and I am guessing that is because the modules themselves are being made in Guangdong province, or somewhere in China.