LDC1000

Hello User,

Thanks for posting your question. LDC can be used to measure changes in deformation provided the spring acts as an inductor and the change in compression can lead to change in inductance our devices can recognize that change and report the changes in a digital output that can be read via I2C. 

However to know if the LDC can work with your device its important that you refer to our FAQ section to get an idea of the Inductance to digital output devices and their capabilities. The key would be to design the sensor in accordance to meeting our device frequency specs. 

For higher resolution application we also highly recommend LDC1614 which has a 28 bit output. 

Hello Arjun,

Many thanks for prompt reply.

To use spring as a sensor,

1. Must both ends of the spring be connected?

2. Is measurement range and sensitivity determined by spring diameter, number of turns, and spring thickness?

3. Using LDC1614,  Is it possible to immediately acquire a signal without a series fixed inductor?

Thank you.

R S 

Hello R S,

In order to check the feasibility of using spring as an inductor first we need to understand the inductance of the spring at rest. After understanding the characteristics of the spring we need to determine if the LDC1614 can drive the sensor and its determined by the Min and max values of the frequency. 

In order to determine if the spring can be used as an inductor I recommend that you order our EVM and follow the design guidelines and steps to make progress and we can certainly help you along the way if you have any questions. 

Hello,

Hope that you are well and good.

I am sorry to get back the topic late.

Should the circuit be connected at both ends of the spring?

Can the spring measurement be done without a coil?

If a coil is needed, should the spring be placed on the coil?

Does the DEMO kit include a PC program?

Thanks,


R S YOUN

Hello R S Youn,

We do have an application note on this topic. 

https://e2e.ti.com/blogs_/b/analogwire/archive/2015/07/13/inductive-sensing-how-to-sense-spring-compression

We highly suggest that there be a series inductor with the spring. As the Spring compression is at rest there is a fixed resonance frequency that LDC can convert. As the spring compresses there is a change in inductance and LDC can detect the change in inductance. 

The Demo program does include the GUI that enables quick evaluation and prototype. 

Let us know if this helps!

Hello Arjun,

Currently, we are using a product very  similar LDC but it is analog magnetic coil.

The frequency of the steel wire is measured by inducing a magnetic field from the magnetic coil by non-contact monitoring.

I ’m still curious about ;

1) Is it possible to perform non-contact measurement with an LDC circuit?

2) Is it impossible to measure without conducting both ends of the sensing spring?

3) I would like to know if the magnetic coil can be replaced by LDC.

Enclosed the picture for your reference.

Thanks

Hello

You certainly can replace the plucking coil which is magnetic today with the LDC coil. If I understand correctly you like to measure the center pressed part which is 4mm and would like to understand the characteristics of the deformation ? Can you help me understand if you would like to measure the thickness ? If the answer is yes, what is the level of thickness you like to measure. Does the center part compress and decompress ?

The LDC coil can be designed instead of the magnets which are inside the plastic casing but the coil needs to be designed such that it can monitor the changes in the thickness. I recommend LDC1614 part for your application. Our FAQ section does indicate steps to proceed with LDC solution. https://e2e.ti.com/support/sensors/f/1023/t/888809/FAQ 

Also, can you please help me understand why you would like to switch from magnetic to a LDC solution ?