Added some spice models of the circuit.

I added a simple spice simulation of the circuit. Some things to note
* When using a relay, always surround the coil with a flyback diode that is reverse biased during normal operation. This will shunt current to avoid the incredibly high flyback voltage that is induced with the relay is turned off.
* I might suggest a fundamentally different circuit - a currently limited voltage source that is switched through power FET.  This will make the circuit much more temporally precise and will limit power dissipation (by limiting the current) to prevent tissue damage. Maybe a switching step-up converter e.g. http://www.linear.com/parametric/step-up_(boost)_regulators