Polarity flipping circuit ...

[qvision]

Hi.

I've googled for hours now and can't find an answer, i hope someone can help me

Is there a simple circuit that can take a DC input and flip it's polarity at a specific frequency ?


Thanks,

Gary.

[rave154]

See here..

http://www.energeticforum.com/renewable-energy/6044-invert-signal-mosfet.html#post103743

read from the start ( there arent many posts ) and at about post #7 i attatch an image.. all the details are there...... not sure if this is exactly what you want though

[qvision]

Thanks very much rave

[rave154]

glad to help, but..... dont thank me...thanks gyulasun...hes the one who basically did it !

also, a nice thing about the circuit is that using the duty cycle on the function gen.....you can say set mosfet-1 to 30%....and mosfet 2 will be 70%......and any numbers you care..including of course 50-50

[qvision]

OK Rave, thankyou Gyula

I don't have a fully-fledged fungen yet, i am using this :

http://www.rmcybernetics.com/files/pdf/PWM-OCXI.pdf

I'm trying to make a sort of solid-state controlled Newman generator, his 'special commutator' just makes my head spin !

So i plan to put the PWM through the polarity-reversing circuit and pulse the coil like that.

I think i may use a 555 rather than the MOSFETS.

Gary.

[nilrehob]

Here is a simple one i have found useful
the coil between the transistors drive the flipping and can be replaced by a sig-gen that gives both plus and minus
the coil at the right is the load



/Hob

[qvision]

Thanks Hob

[qvision]

Please excuse what is most probably my ignorance but i don't think the 555 or h-bridge solutions are what i need.

I'm trying to do a solid-state version of Jo Newman's 'special commutator'.

I've got a PWM that will pulse the coil at 24 Hz.

I want the polarity of the output of the PWM to reverse at 2 Hz.

So, every 12 pulses the polarity should reverse.

Any help greatly appreciated


Gary.

[Michelinho]

Please excuse what is most probably my ignorance but i don't think the 555 or h-bridge solutions are what i need.

I'm trying to do a solid-state version of Jo Newman's 'special commutator'.

I've got a PWM that will pulse the coil at 24 Hz.

I want the polarity of the output of the PWM to reverse at 2 Hz.

So, every 12 pulses the polarity should reverse.

Any help greatly appreciated


Gary.

That would still leave you with the short after every pulse missing. I think the mechanical commutator is still the best option for the Newman motor, not easy to make but well worth the effort.

Take care,

Michel

[qvision]

Michel thankyou, i completely forgot about the short !

Gary.

[nvisser]

Use a normal flip flop ocsilator chip with a Q and Non Q output. When the Q is high the other one is low. You can adjust the frequency and duty cycle with external pots and caps.
Something like the SG3524 or SG3525.
Check out :

http://www.energeticforum.com/renewable-energy/962-use-tesla-switch-28.html#post75195

Post 551 where John Bedini gave a diagram for it
Or use a simple small picaxe chip like the Picaxe 08M. You can easily program it to do what you want it to do