Mpsa13 booster questions

[Kipper4]

I built the LPD MPSA13 Booster on the breadboard. No problem even made a demo.
Translated it to pad per hole and my voltages are completely differant

BB
C 3.3v
B1.75v
E0.65v

Pad per
C7v
B1.5v
E0.45

I swapped out the emitter resistor
the 10M
the1k8 collector resistor
most stuff infact and the replacement values where all checked before replacement
I spoke to Lawerence who kindly provided me with a screen shot of the simmed circuit with voltage.
The sims voltages looked more like the breadboarded version I have.
Which by the way has a far greater gain than the pad per version.

I dont get why my collector voltage is so different.
Throw me a line before I burn my breadboard and throw myself in the water.
Any clues guys?

[Gus]

I posted the following sim some time ago.  Have not built it yet note it has a bias control. Don't use the parts to the left of R9 in the build.

With 9VDC you might want to use a Szikial pair

[Kipper4]

I see that biasing network R4,R5 Gus.
Thanks

[Mr. Lime]

Pretty interesting topic.

Why don't you take it to the next degree and convert the booster to something like the AMZ Mosfet Booster with Buffer Output?
Here are some ideas:


Not sure if that would work..

[Kipper4]

"Not sure if that would work.."

Me either. 5000k. 5M bias resistors hmmmm
Have you built this?

I suspect it would pop some with those switching options too.

I stand to be corrected but thanks for the suggestions though.

[Mr. Lime]

http://www.muzique.com/schem/mosfet5.gif

10M is quite common, never tried a Darlington combination but I read to use it just like a single transistor.
The tone pot is suggested by Fred Briggs.
Hard clipping diodes should not pop at all, have to try the soft clipping diodes in the feedback but in op amp gain stages, they do not pop either.
Just a low part count overdrive/booster/buffer/distortion pedal, a simulation would be nice..

The switches (SW1 3PDT, SW2 On-Off-On) ensure that in buffer mode no diodes are in the circuit. You can ditch them of course but in terms of flexibility and live practice I would keep them.
R2, C2 and R3 could be simplified to one single resistor

[Kipper4]

Ok Thanks for that.

[antonis]

@Mr. Lime:
I'm a little confused with SW1 but if I got it right then you dominate the input impedance by the value of Bias trim (50k) in the boost mode...

As for the 10M bias resistor you've mentioned in Jack's MosFet Booster, it comes after a "stiff" voltage divider..
In your case, you create a voltage divider which is relatively prone to be loaded by MosFet's gate leakage current..

[mac]

"Not sure if that would work.."

It works
In 2009 I posted a booster based on the "Solid State Tube", an idea I found on the net.
And a high gain distortion pedal too.

http://gabevee.tripod.com/sstube.html

BOth in my gallery, My Circuits -> pages 3 and 4. The biasing techniques are included, and sound clips IIRC.

http://www.aronnelson.com/gallery/main.php/v/mac/my+circuits/trasfet+booster/

mac

[Kipper4]

Thanks Guys appreciate the input and ideas.
Currantly working out a PNP Germ and Darlington fuzz idea, besides some clean darlington boosters.

[Kipper4]

Heres a variation of Lawrences MPSA13 Booster.
It has a good feel and good dynamics and a shed load of booster.
Mosfet and Schottky diode clipping on a switch

[Kipper4]

"Not sure if that would work.."

It works
In 2009 I posted a booster based on the "Solid State Tube", an idea I found on the net.
And a high gain distortion pedal too.

http://gabevee.tripod.com/sstube.html

BOth in my gallery, My Circuits -> pages 3 and 4. The biasing techniques are included, and sound clips IIRC.

http://www.aronnelson.com/gallery/main.php/v/mac/my+circuits/trasfet+booster/

mac

Thanks Mac
Bookmarked for later breadboarding.

[Kipper4]

Quick demo of above

https://youtu.be/iPZJnnaENLs

[Kipper4]

And a layout to go with

[antonis]

Rich, your SPST switch shouldn'd be grounded...

I also can see a couple of mistakes, like straight connected Collector & Drain and false wiring pads.. 

[Kipper4]

Thanks but
the collector is tied to the drain because the mosfet is used as a part of the (dirt) clipping mod
ie ;2n7000 mosfet (used as a body diode) and bat 41. that goes to the other pad on the switch.
the pad marked dirt (1 up and 3 in from right) goes to the switch.

So its an option clipping mod if that makes sense.

[antonis]

I refered to your schematic in which the clipping parts are connected via a On-Off switch..

If this switch is the one in your layout then it should be interposed between darlington's collector and MosFet's Drain..


Edit: OK, now I realise that you "cut" the clipping mod via switch and GND...
(Sorry for upsetting you...)

[Kipper4]

You havent upset me man. I aint like that.
You're absolutely right in the schematic i put the switch on the mosfet drain and in the layout its on the ground. I'm sorry for any confusion.
I guess when i made the little vid i just disconnected the diode from ground and made the layout that way. It was just more practical for the demo.

Put it on your breadboard people.
Its the kind of booster i like because not only does it do a sweet no dirt (clean) boost but if you dig in it can push the amp into overdrive.
Note I mostly play with fingers so if you play with a pick it will break up more.
Now if you play hybrid, pick and fingers you'll have more options. Bad luck for me I can't.

This goes for both clean and dirt settings. obviously your gonna get a bit more dirt with the switch on.

I'm using a noisy cricket (Ruby variant) 1watt amp in the demo . mex strat.
Great thing is too it doesnt get too bright, even on the bridge pick up.
you tube compression might not do it justice though.

I tested it with a bigger amp 30watt on the edge of break up and it still performed well.