A rectifier that counts?

R

Randy Gross

Guest
I have looked at quite a few circuits in the last few days: voltage
comparators, frequency to voltage converters, voltage regulators, frequency
counters and magnetic pickups when a thought crossed my mind.

Has anyone used or, know of a circuit that uses the rectifier as a
frequency source instead of a magnetic pickup. Each time the rectifier
conducts positive (or negative for this matter), this is counted for the
time period, converted, and fed to a comparator. Whatever decision is made
is then passed on to the motor speed controller.

I haven't run across one like this, yet. The 3 latter circuits are no
problem. It's the frequency sensing circuit I'm after.

Inquiring Mind
Randy

----------------------------------------------------------
<') >< Homebuilt Arc Welder, Saturable Core Reactor and more...>< ('>
http://www.gomedia.ca/~aaawelder/
Chance favors the prepared mind whose hands do the work!
 
Randy Gross wrote:
I have looked at quite a few circuits in the last few days: voltage
comparators, frequency to voltage converters, voltage regulators, frequency
counters and magnetic pickups when a thought crossed my mind.

Has anyone used or, know of a circuit that uses the rectifier as a
frequency source instead of a magnetic pickup. Each time the rectifier
conducts positive (or negative for this matter), this is counted for the
time period, converted, and fed to a comparator. Whatever decision is made
is then passed on to the motor speed controller.

I haven't run across one like this, yet. The 3 latter circuits are no
problem. It's the frequency sensing circuit I'm after.
Click to expand...
Why not use the AC upstream of the rectifier as the frequency source?
That can be squared up and fed directly to the frequency to voltage
converter, or to the phase detector in a phase locked loop.

--
John Popelish
 
"Randy Gross" <rgwg99@acsplus.com> wrote in message news:<01c3b7bb$5dbde800$332525d8@defalut>...
I have looked at quite a few circuits in the last few days: voltage
comparators, frequency to voltage converters, voltage regulators, frequency
counters and magnetic pickups when a thought crossed my mind.

Has anyone used or, know of a circuit that uses the rectifier as a
frequency source instead of a magnetic pickup. Each time the rectifier
conducts positive (or negative for this matter), this is counted for the
time period, converted, and fed to a comparator. Whatever decision is made
is then passed on to the motor speed controller.
I haven't run across one like this, yet. The 3 latter circuits are no
problem. It's the frequency sensing circuit I'm after.
Click to expand...
I don't think you want to use the diode as a "counter" in itself,
I think you want to use it as a pickup. In which case a photodiode
certainly counts :)

(I originally had a response where I put "diode" and "counts" together
to make a divider, like the old regenerative frequency dividers that were
common in the 50's and 60's, but I don't think you intended to ask about
that subject.)

Diodes are exceedingly common for "counters" of radiation from visible
light on up in frequency. Put a scintillator in front of one and you
can detect non-photons, too. Here I'm using the word "counter" in the
nuclear physics sense, not the electronics sense. Nuclear physicists call
electronic pulse counters "scalers", not "counters" :)

Magnetic pickups have been much more common in typical automotive/
industrial environments than photodiodes because they are nearly
impervious to dirt, grease, grime, and stray light. OTOH inductive
pickups are potentially more sensitive to medium and large-scale EMI,
and in many areas they've been replaced by solid-state Hall detectors
in the past few decades.

Tim.
 
"Randy Gross" <rgwg99@acsplus.com> wrote in message news:<01c3b7bb$5dbde800$332525d8@defalut>...

Has anyone used or, know of a circuit that uses the rectifier as a
frequency source instead of a magnetic pickup. Each time the rectifier
conducts positive (or negative for this matter), this is counted for the
time period, converted, and fed to a comparator. Whatever decision is made
is then passed on to the motor speed controller.

I haven't run across one like this, yet. The 3 latter circuits are no
problem. It's the frequency sensing circuit I'm after.
Click to expand...

Hi Randy. I've seen the transformed 50 or 60Hz used as a clock signal
before, its a minimal cost way to get a pretty steady lf clock.
Mechanical synchronous clocks locked onto mains frequency for decades,
with fairly good results, several are still in use.

Also the ac waveform is fed to a comparator in pseudorandom
generators.


Regards, NT
 
John Popelish <jpopelish@rica.net> wrote in article
<3FCACA20.CCFFEA90@rica.net>...
: Randy Gross wrote:

<Snip>

: It's the frequency sensing circuit I'm after.


Couldn't see the forest for the trees;-)

Randy
:
: Why not use the AC upstream of the rectifier as the frequency source?
: That can be squared up and fed directly to the frequency to voltage
: converter, or to the phase detector in a phase locked loop.
:
: --
: John Popelish
:
 
"Randy Gross" <rgwg99@acsplus.com> wrote in message
news:01c3b7bb$5dbde800$332525d8@defalut...
I have looked at quite a few circuits in the last few days: voltage
comparators, frequency to voltage converters, voltage regulators,
frequency
counters and magnetic pickups when a thought crossed my mind.

Has anyone used or, know of a circuit that uses the rectifier as a
frequency source instead of a magnetic pickup. Each time the rectifier
conducts positive (or negative for this matter), this is counted for the
time period, converted, and fed to a comparator. Whatever decision is made
is then passed on to the motor speed controller.

I haven't run across one like this, yet. The 3 latter circuits are no
problem. It's the frequency sensing circuit I'm after.

Inquiring Mind
Randy

----------------------------------------------------------
') >< Homebuilt Arc Welder, Saturable Core Reactor and more...>< ('
http://www.gomedia.ca/~aaawelder/
Chance favors the prepared mind whose hands do the work!
Click to expand...
Err, perhaps you are thinking of a motor controller driven by some
thyristors or SCRs or other such wildebeasts. Don't know how you arrange the
thingies but you do and then you fire them off from some zero crossing
detector counter other thingy such that, if it were so many bits then it
would go....

On,On,On,On,Off,Off,Off,Off

or

On,On,Off,Off,Off,Off,Off,Off

and all perambulations and combobulations thereoff (or thereon) to achieve
speed control of the motor.

Make sense?

Of Course

AND
 
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