Best way to run a toy DC motor in 2 speeds

[ESTinker]

What's the simplest or best way to run a DC toy motor in 2 speeds (5-12V) with a couple of batteries. Nothing fancy just wanted to know the pros and cons, so far I have come up with these:
1. Gears (add complexity and needs more space)
2. Diodes/Resistors/Rheostat (maybe a diode but don't like the efficiency on resistor/Rheostat)
3. Switch DPDT to run batteries either in series or parallel (probably the easiest)
4. Motor controller (this requires more components and complexity)

 

[TugboatEng]

Pulse width modulation.

 

[waross]

Changing the voltage by changing the number of battery cells is probably the easiest.
The unloaded speed of most toy DC motors is closely proportional to the applied voltage.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[EdStainless]

There are dedicated chips for this application, voltage regulator that use resistors in a feedback loop to set the voltages. Easy enough to switch between two control resistors.
These have the advantage of always being 10V and 5V as long as the batteries are over 10V, and the low speed setting would stay the same down to 5V.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[3DDave]

Drive a 555 with an Arduino.

(Just to see who will spit coffee all over their keyboard.)

A couple of what kind of batteries? 5 and 12 are not numbers that a couple produces.

Lead-acid 2V per cell,
NiMH about 1.4V per cell,
Alkaline about 1.5 per cell,
Li-Ion about 3.8V per cell (not checked for exact value, but over 3.1V and under 4V)

What current draw is there?

The series/parallel is most likely to minimize losses, though switching with MOSFets is also pretty good.

The advantage of the gears is that at the lower speed they will output higher torque.

 

[dArsonval]

A switch.

Speed One.

Speed Two.

John

 

[zlatkodo]

Hi, ESTinker
There is a bunch of inexpensive PWM motor controllers, depending on DC voltage and current required.
Here is one example.
Regards
Motor Winding Design Support

 

[waross]

You can probably second source zlatkodo's offering at Wish.com

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[crshears]

OP doesn't specify that the fast speed is double the slow speed . . . makes a difference, right?

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]