Frequency to voltage converter

B

Thread Starter

BJ_Johnson

I have an application where I need to control the speed of a VFD from an encoder mounted to a conveyor shaft. Unfortunately, the VFD I must use will only take a 0 to 10 vdc analog velocity command. Does anyone know of a source for a stand alone frequency to voltage converter?

input frequency will range from 750 - 1000 pulses/sec to 100,000 pps
a quad b encoder with line drivers

many thanks!
 
P
Why not replace the encoder with a tach? Or, if you really need the resolution of the encoder, is the VFD accurate enough to maintain your setpoints? It sounds like one end or the other of your loop is mismatched to the application... can anybody with a lot of VFD experience enlighten me further (or, BJ <g>).

Paul Tolsma

---------original message-------------
From: BJ_Johnson/Appliedmotion%[email protected]
Subject: MOTION, PLCS: Frequency to voltage converter

I have an application where I need to control the speed of a VFD from an encoder mounted to a conveyor shaft. Unfortunately, the VFD I must use will only take a 0 to 10 vdc analog velocity command. Does anyone know of a source for a stand alone frequency to voltage converter?

Input frequency will range from 750 - 1000 pulses/sec to 100,000 pps a quad b encoder with line drivers

many thanks!
 
Danaher makes a module that will do exactly what you are looking for. Model # FV3, you can select the input frequency range and it will output 0-10VDC or 4-20mA.
 
S
I've seen a frequency to voltage converter that was manufactured by Avtron Corp. out of Ohio. There number is 216-641-8310. I'm not sure what the cost was though. It seems like Action Instruments may have something like that also??

Scott Brown
Gemtron Corporation
 
R

Richard Darin

I have seen many answers to this query however the answers are of no merit because no one asked .What is the specification? ie. What is the operating speed range, long and short term accuracy and what part of the error budget
can be used up by the velocity transducer? Quite honestly I am still surprised after spending 30+ years automating inumerable processes that the
need for a proper specification is not requested before a answer is given.
 
D

Darren Tichbourne

I have built my own using a very wonder ic.
the chip is manufactured by National .... LM 2907 (a few members in family, one with internal zener ref.) 8pin dip package (requires a few external components, resistors and caps)
It's a rock solid one... used in automotive industry in the cruise controls... early ones..
I have used it for detecting blade tip velocity of a lawnmower blade in the past testsets I fabricated (used for over 10yrs). summed signal from 3 inductive sensors, 120 degrees out of phase, fed the signal to the freq. to voltage chip.... output signal produced was dc 0 to
5v... scale it... .. ie 3600 rpm = 3.600 v

enjoy

Darren Tichbourne
President, System Integrator, CET
CompuSys Solutions
___________________________________________________________
Email : [email protected]

Website: www.CompuSysSolutions.com
 
I simply mentioned some possible sources, I did not offer any engineering advice. He only asked for a source, not engineering help.

Bill
 
I wish to thank all who replied with possible sources for this device. I have found a good solution for my application and do not need to take up any more of the lists valuable time with assistance for this.
 
I would assume that repliers were simply pointing the poster in the general direction of potential suppliers. The detailed selection of a device from catalogues, web pages or whatever is the responsibility of the person who made the original
post.

Kind of like, "I'm new in town, I would like to buy a car. Does anybody know where the Ford dealer is?"

Bill Code
MPM Engineering Ltd.
4-6240 202nd St., Langley, B.C., Canada, V2Y-1N2
Phone: 604-534-6605 Fax: 604-534-6693
E-Mail: [email protected] WWW: http://WWW.MPM-ENG.COM
 
Richard,

Long term accuracy??? When did this become a concern when using a V-F drive?? What the heck is an error budget??Operating range was clearly
stated within the original post . .. .Innumerable apps and you have not see this done before???? On the face of things, you are absolutely correct . . . however, a VF drive is about as responsive as a slug relative to any of the products that have been suggested. Even for the most demanding of conveyor following apps for gap control, velocity slaving, or rudimentary positioning, any of the products suggested would suffice. I have seen a variety of different applications very similar to the basic description provided handled using this method. It is not elegant, but it is simple, requires little or no programming and most of the people who would be responsible for keeping it running can figure it out. Perhaps those who made suggestions are in error for not "getting all the details" . . . . but I rather think that in most cases, this is such a mundane and common app that has been solved in this manner so many times . . . . I would be the last to poo-poo the importance of good specsmanship, but your comments illustrate that either you mis-understood the application or perhaps are used to doing
government contracts with unlimited budgets.

KB
 
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