JFET Nixie Tube Driver

This is a driver circuit for nixie tube. This circuit uses 2N3684 as nixie tube drivers because its Vp is 2-5 volts which is ideally matches TTL-DTL logic level. Compared with bipolar transistor, the JFET is immune to almost all of the failure mechanism found in bipolar transistor. Here is the circuit :

To prevent breakdown of the JFETs, this circuit uses diodes that produces +50Volt prebias line. There is no voltage connection on the transistor ‘s can since the 2N3684 is in a TO-72 package. [Source: National Semiconductor Application Note]