Monday, June 4, 2018

Can a single BC337 or BC647 direct drive an 8 ohm speaker?


It should be possible. Operating in class A (electrons flowing all the time). If they operate as well as the 2N3053 on the Pleiades 2N3053 driving the Philips AD5046N the sound should be excellent.


These transistors with schematic were found while searching on google for:
schematic of masquito ultrasound repelent


A resistor from collector to hase can provide bias.


The 8Ω speaker can be connected to the collector. A fuse should be included in case of thermal runway with possible damage of transistor or speaker. A battery should have a fuse anyway.


Emitter can be connected to gnd.


A series resistor to base can adjust volume.


See also the Pleiades 2N3053 schematic directly driving the Philips AD5046N 800 ohm speaker. Current in this case is only 8mA and power consumption very low.



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