Electrovibe Build w/Monk Mods

[Feral Feline]

I’m just about to start building my first Electrovibe. @Big Monk (or somebody else), can you explain to this idiot what you mean by ”Replace Q1/Q2 with a single MPSA13.” Can I solder in a MPSA13 in Q1 and leave Q2 empty, or what?

In addition to what you posted...
You'd need to jumper Q2's BASE & EMITTER.


Or you could do it the other way 'round (whichever is easier done on the PCB):

 

[m00ni]

Thanks, I’ll give this a shot!

 

[Feral Feline]

Or you could stick the MPSA13's BASE and COLLECTOR in Q1 and bend the EMITTER-leg around to Q2, that would work as well, so long as you don't short any of the legs against each other.

 

[Big Monk]

I’m just about to start building my first Electrovibe. @Big Monk (or somebody else), can you explain to this idiot what you mean by ”Replace Q1/Q2 with a single MPSA13.” Can I solder in a MPSA13 in Q1 and leave Q2 empty, or what?

I think I would recommend the following if you wanted a good mix of vintage/modern performance:

Q15 = BC547B
Q5, Q6, Q8-Q12 = BC547A
Q14 = BC547C
Q1/Q2, Q3/Q4 = MPSA13

As far as how to install the MPSA13 in place of two transistors, notice how the pairs in question are actually already wired as true darlingtons, as opposed to the pairs in the phaser stages, where on collector has a resistor:

LFO/Bulb Driver:



Phase Stages:



The easiest way to make the true darlington install would be to make the install of the single darlington into Q2 and Q3, and simply install a jumper wire from base to emitter on Q1 and Q4:



Since 2n5088 and MPSA13 both have the same orientation, it should work out like this, and this is how I did it in the past:

 

[Big Monk]

In addition to what you posted...
You'd need to jumper Q2's BASE & EMITTER.


Or you could do it the other way 'round (whichever is easier done on the PCB):






View attachment 118165

This is the cleanest way.

 

[m00ni]

Thanks @Big Monk - really appreciate this.

 

[swelchy]

 

[Feral Feline]

I think I would recommend the following if you wanted a good mix of vintage/modern performance:

Q15 = BC547B
Q5, Q6, Q8-Q13 = BC547A
Q14 = BC547C
Q1/Q2, Q3/Q4 = MPSA13

...

FYP
(Don't forget Q13)