1V p-p sine > TTL signal conversion

[DanT]

Hi -we need to run a large motor - The motor is 460 Volt 3 phase 4 pole squirrel cage asynchronous with a built-in encoder. The encoder's output is 1 Volt sin/cos.

We have a nice vector drive, but it only accepts TTL or pulsed signals from motor's encoder.

I suspect there is a simple device to take the 1 Volt sin/cos and use it to 'create" a TTL output.

Can someone point me in the right direction ?

THanks,

Dan T
Dan T

 

[Comcokid]

DanT-
What you want can be accomplished with a simple comparator-type circuit. Look at devices such as:

http://www.national.com/ds/LM/LM139.pdf

This device has a open-collector output - just use a pull-up resistor to your TTL supply. You may have to power the op-amp from a positive and negative supply depending upon your input signal and just where you want the trigger threshold. Depending upon how fast the edges of your 1Vpp signal is and presence of noise, you might have to add a little hysterisis. Additional app notes on comparators can also be found at this web site.

 

[nbucska]

I would add a deglitcher -- to design it, need RPM of motor
and number of encoder cycles per rev. (is it one sine,one cos or N sines and N cosines ? ) and your fax#


<nbucska@pcperipherals.com>

 

[FTH]

If you want to buy a module you can check the 'CP-1064. Sinewave Interpolator' on

http://www.opticalencoder.com.

As a more robust design alternative you could check the 'MT-series' on

http://www.optical-technology.com

For the same reason you can check the interpolator products from Heidenhain.

Rgds,
Frank

 

[AndyHill]

You could use an opamp then schimtt trigger

Use the opamp to gain the signal up to 0 - 4.5~5v then run it through a schmitt trigger to square it off this would then become a TTL square wave.


Andy