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The first transistor is decoupled from the rest of the circuit and the emitter is at the -3v rail, so as far as that transistor is concerned, it is biased with the collector in the middle of a typical 6v unsplit supply. The signal coming from there is great at about 4v pk-pk.

I made the assumption that the hfe shown on my little transistor tester was the right number to use for gain calculations.... It was pointed out to me that the hfe is not the same at high current and pushing to the voltage rails compared to a small signal at a minimal current. I measured the hfe under the conditions I wanted it to work at and the hfe wasn't the 200 my transistor tester showed, but about 35 in this case. After adjusting for the new hfe value, it worked much better. I am going to experiment with bootstrapping as well, I just haven't got to it. Long story short, I should have designed it with the datasheet minimum hfe to start with.

Edit: while I can still, I made a few typos in the first post. I was giving it a 1v pk-pk signal and needed 4v pk-pk out.

<blockquote data-quote="brandon7861" data-source="post: 794136" data-attributes="member: 53724">The first transistor is decoupled from the rest of the circuit and the emitter is at the -3v rail, so as far as that transistor is concerned, it is biased with the collector in the middle of a typical 6v unsplit supply.&nbsp; The signal coming from there is great at about 4v pk-pk.I made the assumption that the hfe shown on my little transistor tester was the right number to use for gain calculations....&nbsp; It was pointed out to me that the hfe is not the same at high current and pushing to the voltage rails compared to a small signal at a minimal current.&nbsp; I measured the hfe under the conditions I wanted it to work at and the hfe wasn&#039;t the 200 my transistor tester showed, but about 35 in this case.&nbsp; After adjusting for the new hfe value, it worked much better.&nbsp; I am going to experiment with bootstrapping as well, I just haven&#039;t got to it.&nbsp; Long story short, I should have designed it with the datasheet minimum hfe to start with.Edit: while I can still, I made a few typos in the first post.&nbsp; I was giving it a 1v pk-pk signal and needed 4v pk-pk out.</blockquote>

[QUOTE="brandon7861, post: 794136, member: 53724"] The first transistor is decoupled from the rest of the circuit and the emitter is at the -3v rail, so as far as that transistor is concerned, it is biased with the collector in the middle of a typical 6v unsplit supply. The signal coming from there is great at about 4v pk-pk. I made the assumption that the hfe shown on my little transistor tester was the right number to use for gain calculations.... It was pointed out to me that the hfe is not the same at high current and pushing to the voltage rails compared to a small signal at a minimal current. I measured the hfe under the conditions I wanted it to work at and the hfe wasn't the 200 my transistor tester showed, but about 35 in this case. After adjusting for the new hfe value, it worked much better. I am going to experiment with bootstrapping as well, I just haven't got to it. Long story short, I should have designed it with the datasheet minimum hfe to start with. Edit: while I can still, I made a few typos in the first post. I was giving it a 1v pk-pk signal and needed 4v pk-pk out. [/QUOTE]

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