Rapid polarity switching

Hi I have looked everywhere before posting this.
Is it possible to get the pwm pins on the uno to switch polarity rapidly? An h-bridge can change a motors direction (polarity), but i need this to happen repeatedly and very fast. I am making an electromagnetic pulse motor.. It already works well using only repulsion, however I imagine if I could take advantage of attraction as well I would have increased torque/performance. Any and all input is appreciated, thx.

What frequency, what current.

Three amps and variable frequency (pot)

What frequency RANGE?


Oh, I thought you wanted "rapid"? The UNO processor works at 16MHz. This means it can perform 160,000 instructions in one half-cycle of 50Hz. That should be enough to calculate the correct time to turn the magnet on.

Somehow I suspect that the actual magnet switching will happen faster than 50Hz. How many magnets?

right! thx, so the frequency is not a problem. It IS 50hz, 5 larger neo magnets, 10 revolutions per second max... still the question though; how can i switch the polarity?

A H-bridge will be able to do this.

Thx Larryd, thats all i needed to hear. I have been searching for a schematic for a long while, any suggestions?

What is the rate voltage for the magnet.

I have 12 and 24 volt, for what i am doing 12 volts works well. I am using a darlington pair to power the emagnet.

For 3A H-bridge have a look at some of the Pololu MOSFET H-bridges, most high current
H-bridge chips are MOSFET surface mount versions, so break-out boards are usually
needed and Pololu have a nice range - although other suppliers are of course available.

50Hz is 4 orders of magnitude below "rapid" in my book. Words like "fast", "high current"
etc are meaningless, actual numbers are informative. High current could mean 100mA or

Thx markt.. I will check out pololu. Also, i will try and be more specific with my questions in the future.

As MarkT has said.
For a discrete option Google: h bridge images MOSFET

You may find this interesting:

See 8:30

Thx larryd thats exactly what i needed, i really appreciate this.