A sketch (& much less a detailed drawing) can't be sent you because you haven't furnished an address.  Additionally, this site doesn't permit publishing addresses so don't even try.

However, your question is very simple: a JT (Joule-Thomson) valve is nothing more than an expansion valve - usually constructed very much in the style of a needle valve.   You can achieve the Joule-Thomson effect (the free expansion of a compressed gas or gaseous mixture) using any throttling valve - but a needle valve has proven to furnish the operational control sought.  In the "oil patch"  this valve is usually called a "choke" or a choke valve and it usually is fabricated in the style of a 90o (or angle) valve.

Straight cage/globe valves can also function as a JT valve.  I have selected cage style globe patterns for the JT around a turbo-expander compresser.  I second Montemayor's choke suggestion too.

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