AMZ Mosfet Boost - Cool!!!

[vanhansen]

This is more of a thanks to Jack for coming up with the Mosfet boost.  I was working from home yesterday and decided to do some "other" work as well.    So, I fired up the soldering iron and soldered away.  The night before I had put it on the breadboard to see if I even liked it and I did.  The layout I used is the vero layout Torchy did (basic layout, not the enhanced version) but since I don't have any vero board, I did it on perf.  Easy as pie too.  The component leads worked nicely for creating the full "vero-like" track.  It's a little tight in some spots but it's together, pretty compact, and it fired right up first time.   That's always a good feeling.  It's biased around 5-5.3 volts with a BS170.

I'm sure he's heard this a million times but sometimes it can never be enough.  So, thanks, Jack.  This is one cool booster.

[gaussmarkov]

i'm happy to pile on to this thread.    i highly recommend this circuit.  and i think it was the first circuit i made.  use it alone--use it in combination--jack's mosfet booster is a great ingredient. 

[vanhansen]

Thanks for piling on.    It appears spring break extends to the forums too. 

It was your first project?  Cool.  It's about my 10th or 12th, something around there, but the 9th that's actually been put in an enclosure.  I have a few others that either aren't boxed up or were just done on the breadboard and haven't gone any further than that.  I liked the Mosfet Boost enough to bump it up and get it a home.  Lately I've been trying out all sorts of different boosters to push my Marshall.

[gaussmarkov]

yep, first project.  i was actually hanging out at the tophat amps forum when someone referred to jack's booster over here at aron's forum.  so i came over to see what this was all about.    so jack's mosfet booster actually got me here in the first place.  i have been running jack's booster into my tophat club royale ever since and i am still digging it.    i also built a double booster, which a friend has, and jack's fave, a mosfet booster into a mini-booster, also out on loan.  i'm thinking of teaming it with a red llama.

[vanhansen]

Wow, I'm impressed.  My first project was the beginner project.  I didn't even know what a mosfet was when I started so I sure wasn't going to tackle anything that uses them.  I'm curious about the mini-booster but even Jack stated on the Mosfet Boost page that it retains the natural tone better.

What value/type gain pot did you use?  I've got a 5k Linear in there now per the schematic but amount of gain jumps at around the last 5-10% rotation.  It's a real gradual increase up until that point and then BAM, it jumps up and that is where it starts to distort some, but pleasant.

[gaussmarkov]

ah shucks, it warnt nuthin special.    it took a long time to complete.  i went very slowly, triple checking everything as i went.  but it fired up first time!   

i got all the parts locally.  this was before smallbearelec and mouser became my sources.  my pot is marked 5KA and i'm pretty sure it's audio taper.  it's so cheap it doesn't say who made it.     and the mosfet is rat shack's IRF510--they didn't have the IRF511 jack lists.  so it has less gain than yourBS170.  these differences may explain why mine doesn't have the big gain jump you describe.

[vanhansen]

My entire beginner project is 100% rat shack parts...LOL.  I still get perfboard there and a few other oddities here and there.  In fact, I just picked up a new desoldering pump there, a real nice one too.  I needed more braid and remembered I needed a new pump too.

I've gotten some MPF102's and other transistors from them, like the assortment pack, and used them here and there.  The rat shack pots are actually Alpha pots.  I rarely have problems with them.  For now I'm just going to leave the 5k-B in there.  It works.

When something fires up first time, it's a great feeling.  The last few builds I've done have been that way.  I believe it's because I take more time to really study the circuit before getting the iron hot.  The breadboard is probably my biggest learning tool.  When I first put the Mosfet Boost on it, I ran in to some biasing issues and had to fiddle with things so I was able to make quick changes, check-double-triple check everything, check voltage readings, test it out, the whole shabang.  Low parts count has it's advantages too.

The Mini-Booster may be next but I think I want to order a couple PCB's from Jack first, one for the Mosfet Boost and one for the Mini-Booster.

[gaussmarkov]

  cool.  actually, i got the pot at an old electronics supply store here in berkeley called Al Lasher's.  i try to go in there whenever they might have what i want.  a lot of their stuff is obscure chinese manufacture.

i've never bought a pcb, or etched one for that matter.  another forumite kindly etched one for me and pcbs rule when it comes to the big circuits.  i've been happy with perf so far because i have been making the simpler projects.  like you, i learned it from the beginners' project (yay aron!).  and i have enjoyed doing my own layouts in eagle.

about the breadboard, i totally missed how useful that is at first.  finally, after seeing breadboards discussed for the tenth time i got one and now i understand.  you're right.  they are a great way to learn and experiment.  now that i am using breadboards too i do a breadboard layout and a perfboard circuit layout.      i suppose that's a little compulsive--but hey, i'm enjoying it.   

[vanhansen]

Doing a project on PCB will be a first for me.  Everything has been perf, even if it was adapted from a vero layout. 

Doing layouts, no matter what format, I find to be so helpful.  As long as it's still fun, I'll keep doing it.  It's all about fun for me anyway.

[gaussmarkov]

by the way, i like your website.  thanks for putting that up.  it's more work than most of us realize.  i recently acquired gaussmarkov.net and plan to start posting somethings there but i don't want it to be lame.  so it's taking a while.  .... 

[vanhansen]

Thanks.  It's changed face a few times and changed locations once.  It grew too big for my ISP's personal space.  It took me a few designs to get to where it's easier to maintain.  CSS absolutely rocks.  That saved loads of time right there.  I had the Mosfet Boost page up in a matter of minutes.  I just copy the last page I did, change the content, add a link to the index and upload.  What takes the longest now is coming up with what to say. 

[Guitar Toad]

Nice report Erik. Are you gonna try one of the new low voltage boosters next on the AMZ site?

I'm slowly getting parts in to build the Liquid Drive and RangeMaster and RangeBlaster.

I agree. You have a great page. I look at it a couple times a week.

Thanks for the report on this Mosfet Boost. I may need to try it sometime.

[vanhansen]

Thanks, Todd.  I've looked at the low voltage boosters page several times.  I may try one out on the breadboard.  If anything it'll be a learning experience.

Thanks for looking at the site and enjoying what's there.  It's nice to know that folks are liking what they see.

[squidsquad]

Of the many things I've built...the Mosfet Boost is the one that goes to ALL gigs.  I run it slightly above unity...and it helps preserve the high end when I run thru my Memory Man & Electric Mistress.

The Mini-Booster is also great & easy to tweak.

[vanhansen]

Hey, thanks for chiming in, squidsquad.  It's always nice to hear from you with all the experience you have. Last night I messed with seeing how it behaved with the gain set lower and I found the same thing as you, it adds some more high end and sparkle.  I guess this could also be used as a variable gain buffer of sorts.  Either way, I like it.  It's very "non-interfering" to the original sound which I like a lot.