[sdiy] Transistor type flip-flop circuit.. What makes the 'power up' state of it ?

[Ben Bradley]

I at first wondered if there's a missing component in that schematic,
because "those two 1 meg resistors at the collector of  Q7 can't be enough
to unbalance it," but the more I look at it the more I think that's it.
Five percent tolerance resistors should be enough for 500k from Q7 to
ground to imbalance things enough to guarantee that Q6 goes up. You can
demonstrate that by connecting the two 1 meg resistors to Q6 instead. and
see that Q7's collector always goes high.

On Wed, 31 Jan 2024 at 10:46, Jean-Pierre Desrochers <jpdesroc at oricom.ca>
wrote:

> Hi list,
>
> I have a question about the behaviour of transistor type flip-flop circuit
>
> When the DC power is applied to it..
>
> The following schematic of Boss CE-2 pedal shows the flip-flop at the
> bottom right.
>
> Why when the DC power is applied :  collector of Q6 goes high (to make the
> pedal in the ‘no effect’)
>
> And it’s not Q7 that goes this way instead ?
>
> I know that C23 (.01uf) pull down the trigger input when DC is applied
> to put the pedal in the ‘no effect’ position, but why is Q6 selected ?
>
> This is a ‘balanced’ flip flop circuit and both sides should behaves the
> same
>
> But some kind of selection is done here.
>
>
>
> Could someone explain that behaviour ?
>
>
>
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