Q&A

# $Q$ and $\overline{Q}$ in bistable multivibrator

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In this bistable multivibrator which is $Q$ and which is $\overline{Q}$?

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Whichever you choose.

I notice that you deliberately made the gain of one transistor a little higher than the other. That is irrelevant. The positive and negative outputs don't depend on the power-up state. They depend on which way the outputs go in response to inputs, like SET and CLEAR.

You show connection points to the two transistor bases. Those can be used as SET and CLEAR inputs by pulling them low. Once you define which is the SET and which is the CLEAR, you'll know which output is the positive and which is the negative. The positive output should go to TRUE as a result of a SET, and FALSE as a result of a CLEAR.

As an aside, you never get to define the gain of bipolar transistors so closely that a nominal gain of 101 is in practice any different from a nominal gain of 100. BJT gains are usually specified to minimum guaranteed values, with the maximum left open. I have personally measured transistors with a minimum gain of 50 actually being nearly 500. Then the next one out of the bin was only 250.

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