want to connect headphone output to base/emitter of switching 300mw transistor whilst running sq wave gen app. to test e-speedo/wiring. hall effect trigger. how to avoid blowing things up? have 4.7k and 5.1k resitors, 9 ea. expect volt divider input with transistor pulse-shorting one. at low Hz.

 

Do you know the approximate voltage amplitude at the output of the phone?

 

Do you know the approximate voltage amplitude at the output of the phone?

no, that's why i'm here. headphone/buds impeadance? power??

 

want to connect headphone output to base/emitter of switching 300mw transistor whilst running sq wave gen app. to test e-speedo/wiring

Get to the point. As scientists we are trained to describe a ton of details and background information before we give the final results.

 

Line level output standard is 0.77V into a 600 ohms load, but most headphones are anything from 16 to 100 ohms, best solution is to measure it..

 

thx that wont blow a b/e junction.