This DIY velocity transducer may be useful for some people here.
https://www.edn.com/low-cost-vibrat...signIdeas-20220621&oly_enc_id=0573J0131245I9E
https://www.edn.com/low-cost-vibrat...signIdeas-20220621&oly_enc_id=0573J0131245I9E
I'd describe that as an acceleration/displacement transducer? To get velocity would require a fair bit of signal processing.
https://instrumentationtools.com/moving-magnet-type-velocity-transducer/This type of device was developed for its first industrial use in the late 1940s by Arthur Crawford, and its application was extended during the 60s and 70s.
But strictly speaking this measures the relative velocity of the coil to the magnet not the transducer relative to some other reference frame.https://power-mi.com/content/seismic-velocity-transducers
https://instrumentationtools.com/moving-magnet-type-velocity-transducer/
Principle of Moving Magnet type Velocity Transducer
When a permanent magnet moves inside a coil, the change in the length of the air gap varies the reluctance. Hence the output voltage is directly proportional to the rate of change of the length of the air gap (change in length produced by velocity). Thus the output voltage becomes a measure of the velocity when calibrated.
Sure, it's accurate, when calibrated (compared to a standard) and used properly.But strictly speaking this measures the relative velocity of the coil to the magnet not the transducer relative to some other reference frame.
https://transtekinc.com/teknotes-linear-velocity-transducer-calibration-report/Unlike LVDTs, these transducers do not produce a voltage output unless the magnet is moving. This makes it impossible to electrically identify the correct location of the magnet for linear operation. Users must mechanically position the magnet in the LVT at a known reference point.
The Trans-Tek Series 100 Linear Velocity Transducers produce a DC output voltage proportional to the velocity of the magnet relative to the coil. These units are designed and tested to assure that they conform to prescribed specifications. Each unit is calibrated by our QC Dept., and a strip chart recording of the results are packaged with each unit.
So to be clear, if I had one of these transducers in a system sitting on the passenger seat and switched off. If I drive along at 20 MPH and switch the device on, would it tell me I was driving at 20 MPH?Sure, it's accurate, when calibrated (compared to a standard) and used properly.
https://transtekinc.com/product-categories/linear-velocity/
https://transtekinc.com/teknotes-linear-velocity-transducer-calibration-report/
No.So to be clear, if I had one of these transducers in a system sitting on the passenger seat and switched off. If I drive along at 20 MPH and switch the device on, would it tell me I was driving at 20 MPH?
No. The signal is generated by the motion between the coil and magnet. No motion, no output. Its intended use to to measure vibration.So to be clear, if I had one of these transducers in a system sitting on the passenger seat and switched off. If I drive along at 20 MPH and switch the device on, would it tell me I was driving at 20 MPH?
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