Re: [CAD_CAM_EDM_DRO] Re: Breakout board or cards - charge pump ?

turbulatordude wrote:

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, Stephen Wille Padnos
><spadnos@s...> wrote:
>
>
>>turbulatordude wrote:
>>
>>
>>
>>>As I understand, Mach2 is the only software that uses the feature.
>>>
>>>It outputs a frequency signal on one pin.
>>>
>>>with a comparitor, resistor and cap, you can generate a simple
>>>
>>>
>filter
>
>
>>>that will be charged with the signal and the comparitor can see
>>>
>>>
>the
>
>
>>>elevated voltage, then turn on a curcuit that would allow the rest
>>>
>>>
>of
>
>
>>>the board to be live.
>>>
>>>It is more complicated than that. I would put a PIC on the input
>>>
>>>
>and
>
>
>>>do it in software, or an op-amp to boost the signal, filter it and
>>>act as both the comparitor and output filter (to prevent noise
>>>problems)
>>>
>>>
>>>
>>>
>>Yes - it is more complicated. If the software crashes and leaves
>>
>>
>the
>
>
>>port bit in the high state (or the POST routines happen to do
>>
>>
>that),
>
>
>>then everything looks fine to the comparator. This can easily be
>>
>>
>solved
>
>
>>with a microcontroller, or even easier with a one-shot in the
>>
>>
>circuit.
>
>
>>- Steve
>>
>>
>
>Correct, pulse detection needs to ignore the high and the low.
>
>A Charge Pump takes the frequency and by means of charging a
>capacitor, generates a higher voltage from the signal voltage (or
>something similar)
>
>

Right - you need to throw in a diode or two to get a charge pump. :)
(an R-C circuit would just be a filter)

>either way, the signal needs to detect in the pulse is present and
>ignore the port being high or low in a steady state.
>
>And a PIC would offer a means of detecting a pulse and responding
>accordingly.
>
>

What's wrong with an AVR? :)

>It is interesting to see how much of the posts are geard toward
>buying things and less of the making things we had some years ago.
>
>Dave
>
>

I've only been on this list for around 6-8 months, so I can't see any
specific trends. I think it's similar to a lot of other markets. There
are now enough old machines, and people interested in fiddling with
them, that there is a hobby market for machine retrofit pieces. I've
thought about building some (and have built one item).

I'm doing a retrofit because it's a neat thing to do, but I'll also want
to use the machine, hopefully to make some money. In the end, if my
schedule gets tight (like - other work butts in), then I might buy some
pieces that I otherwise would have built, just to save a little time.

I think that there's a general shift in attitudes today that time is
money, and that it's stupid to spend time (usually called "wasting") on
something that you can buy cheap.

(personally, I'd rather spend the time, but I don't always have that
option, what with bills and all :) )
- Steve