| I'm not grasping the concept of why the MPSA42 method works on | the cathode side but not the anode side. | | Any further insight/explanation would be appreciated.
What don't you get ? Put up a drawing, so you can reference what you don't get. The most commonly used nixie driving, uses 'common emitter' stages on both sides. Here's a drawing of the classically used ckt for driving a mux'd nixie: http://cid-f9db37b8211ce831.office.live.com/self.aspx/Snippets/Nixie_Muxd.gif The Jason Harper anode drive Muntz's the circuit by putting a resistor in the emitter leg (of Q2 of my ckt). This does double duty of limiting both collector and base current, but you need better knowledge of how transistors work to really understand th 'magic'. Don't get rid of the 'bleeder' resistor !!!! Its there for speed. If you think you can shortcut this circuit, by omitting Q3 (MPSA92), and using Q2 as an 'emitter follower', it won't work. Think about it. If its an emitter follower, with the collector (of Q2) to +180, and the anode resistor to the emitter, you get squat. THINK ! THINK ! THINK ! The anode needs to get to 180V. That means the emitter needs to be at 180V. Where's the Base ? It ain't going above 5V. Last I checked 5V is less than 180V. In reality, the emitter won't go higher than the base, which is only 5V. For a mental exercise, if the emitter did get up to 180V, the BE junction would be in reverse bias, since the base is less than the emitter, hence it would clearly be OFF. No current flow. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
