On Sunday 27 January 2019 11:33:39 Jon Elson wrote:

> On 01/26/2019 07:15 PM, Gene Heskett wrote:
> > I've about give up on controlling this VFD with a pwmgen
> > directly as I have no way to step the 5 volt pwm up to a
> > 10 volt pwm.
>
> Can you program the VFD so 5 V input is the top speed you want?
>
If there is such a register, it is not adequately described in English.
At about 98% duty cycle, 5 volt pwm, it actually runs at about 5400 revs, 
or half speed at half voltage=1/4 full speed, which ought to be 6000 
revs. But there appears to be a fixed loss at the low end. I haven't 
measured the timings quite that accurately. This is treating the pwm as 
an AVI input, there is no response when the input is set for PWM but the 
waveform is only a rail to rail 5 volts. It might work at 10 volts but 
I've no quick and dirty way to step it up to 10 volts p-p. So there is a 
50% nominal error I can't explain.

So I'll just put in the c41.  That will likely require I reeassign the 
fwd wire to supply the bobs 5 volts to the c41 as input logic supply. 
Then the question is, has the 12 volts from the vfd got enough currant 
to run the relays, or do I have to break into my jury rigged 24 volt fan 
supply for that 200 ma. TBD.

Frankly, this is being a big enough problem that I think the first box 
completed in this 2 box project, will actually go to the 6040 interface. 
I've ordered another 7i76d from mesa, which has this c41/spinx1 built 
in, so I will shortly have enough stuff to make both.

> Jon
>
>
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>



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