No! Its only bootstrapped to the Vcc rail.. this can be 18~36v after its converted there is another dual op amp that generates the 4~20mA....
The 555 and the two op amps only see a Vsup of 2.5v ~ 3.0v... I have decided to rip the working one apart and compare the voltages to and from the 555.... If I have to replace it I'll meander down to my local PCB shop and see if they will replace it...
I have tried to recreate the circuit, but it might not be entirely accurate...
View attachment 90927
Remember the components may not be correct