Makeshift Amplifier

120

01:48:26

No goal for this, just for fun.
I was designing an amplifier when I realized I cant make it since Im very limited when it comes to parts. I made this amplifier from some 2N2222s and a 30N06L.

1.1 Watt RMS
0.84 Watt Power

Parts:
NPNs - 2N2222
MOSFET - 30N06L

published 7 years ago

hurz

7 years ago

Its not the first time I see that in your circuits, but I hope you do not connect a loudspeaker to dc current as you do here

sshsslfun

7 years ago

I see what you're saying. Btw its not a loud speaker, just a 4 ohm bass speaker I scavanged from an old audio system. I tried connecting a capacitor to the speaker and the signal is blocked as if it were DC, I dont understand why its DC current and not AC? Can I get some help on this one?

crake

7 years ago

in series with output of the mosfet?

jason9

7 years ago

The signal is blocked because the amplifier needs some passive current through it to give an output (consequence of the design). Try putting a 4 ohm resistor in place of the speaker (or anything resistor around the same resistance as the speaker) and then connect the speaker parallel to the resistor with a large capacitor in series with the speaker to prevent DC current. Optimally the resistor would be replaced by a constant current source, but a resistor should work just fine. I’ll give a link for the circuit described..

jason9

7 years ago

http://everycircuit.com/circuit/5117909235138560

hurz

7 years ago

Right, with a capacitor decoupling the DC and additional relay to avoid power on blob. With a upper corner frequency of about 13kHz when used 30N06L as voltage follower and all its parasitic capacitances. THD we better not talk about, since there is no feedback loop. I can think of use for old vinyl record player 10mV input as low perfomance amplifier.

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