Here is a small and simple project.
Two 9V Batteries power one opamp to give a Gain like 5.
That is all that is needed for HiFi amplifier.
Two 9V Batteries power one opamp to give a Gain like 5.
That is all that is needed for HiFi amplifier.
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Here is the 3 transistor variation.
Battery driven with 9+9V = 18 Volt.
It draws only 2.11mA, so there is no worry batteries will be empty soon.
Adjust for 12.0 Volt at output node.
Distortion is a bit higher than with an opamp, but it is still low dist.
THD 0.006% is very good for a so simple circuit.
Battery driven with 9+9V = 18 Volt.
It draws only 2.11mA, so there is no worry batteries will be empty soon.
Adjust for 12.0 Volt at output node.
Distortion is a bit higher than with an opamp, but it is still low dist.
THD 0.006% is very good for a so simple circuit.
Hi, tl072 isn't good for 600R loads (lots of distortion), why not substitute a better opamp? Do you have any other in mind with low consumption?
THD is one thing, but what about THD+N? In "The Art of Electronics" they remarked that op-amps could be thought of as "gain engines". You could try adding a JFET input stage to a bipolar op-amp, and/or add a single-ended output stage to drive headphones.
My guess is that by increasing the gain at the input with a JFET, you could make the total noise go down, as compared to the op-amp on its own.
But I still like the 3 transistor version just on principle. The version my dad made for me as a kid ran on a 9V battery, which probably had several Ohms ESR. So a capacitor could help stiffen rails, and one technique you could try is to put the signal generator on the +ve voltage rail and then play around with the design to increase PSU noise rejection.
My guess is that by increasing the gain at the input with a JFET, you could make the total noise go down, as compared to the op-amp on its own.
But I still like the 3 transistor version just on principle. The version my dad made for me as a kid ran on a 9V battery, which probably had several Ohms ESR. So a capacitor could help stiffen rails, and one technique you could try is to put the signal generator on the +ve voltage rail and then play around with the design to increase PSU noise rejection.
True, but... at typical signal levels the TL0xxx series opamps can be subjectively excellent. At 2 volt rms output we see only a 4.7milliamp peak swing into 600 ohm which is no problem for the TLOxxx series of opamp. I still rate these chips very highly for subjective audio quality.