Jo,
I must admit it's a nice circuit. ( I don't saw it till now )
Pretty bad it can't work at 1KW too...
I've guess the pnp is made by a pnp driver and a HV power npn, else is
difficult to get pnp's at 1500V ( like BU508 ).
The only thing I do not like is the final's damage if a wrong sequence
command comes from PIC ( like Murphy said, the power transistors will
protect the fuses...)
How about the variation range ? Does it goes less than 40...50% of maximum
speed ? And near the 100% ? But about the noise ? I've guess it say:
"wruuuum" some time ( in slang we say it doesn't goes "roundly" )

all the best,
Vasile

On Thu, 28 Feb 2002, Jinx wrote:

> > For 0 to 100 %  speed variation you need a frequency variator
> > and not a dimmer
>
> Hi Vasile, I was going to suggest that but it seemed like a lot
> of work for just a fan. You're right that a synchronous motor will
> not be successfully controlled over a wide range with power
> chopping. Perhaps you'd like to comment on this circuit, which
> rectifies the AC mains to DC that the PIC can then apply to the
> motor
>
> o/p transistors are BU508Ds or similar (700V 8A). Resistors
> "a" to "d" might not need not be there and "e" and "f" could
> possibly be replaced with 10n caps. Snubber across the motor
> is 100 ohms + 100n
>
> I was helped a while ago with this circuit by Roman and Peter Peres
>
>

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