On Tuesday 01 April 2008, [EMAIL PROTECTED] wrote: >Jim, > >Most audio amplifiers have a large capacitor on the output to block DC >current. DC is not good for speakers. Class D power amps use PWM based >drivers that might work for driving motors. I am not sure but I don't >think they have the caps on the output. You would have to look at the >specs for audio amp to try and identify what class amp is being used on the >output stage. > >I think you might be better off building your own VFD driver. Especially >if the PWM is being done though HAL. Why not try using the stepper driver >H bridge and drive it directly from HAL running in PWM mode. As long as >it's heat sinked, you should just fine. The L298 just might work well for >this. > >Jim Combs > There are no caps on a class D output, in fact the circuitry is isolated from as much capacitance in the load as possible with an inductor. Anything over 10 pfs or so just wastes switching power in the active parts and can lead to the destruction of the parts.
For small power requirements, say 40 watts, Ramsey Electronics has a little 2" square, no heat sink required, 40 watt class D amplifier featured rather prominently on the front page of their latest catalog, not terribly expensive either. I would think, thinking as a C.E.T., that a few tens of microhenries of choke isolation on each output lead would allow any number of them to be paralleled for enough power to build your vfd regardless. 10 of them for a 400 watt vfd would probably still be cheaper than a commercially built vfd of that same power level. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Yow! Are we wet yet? ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
