AMZ / Jack Orman Mosfet boost + Mini boost - 2 pcbs OR dual booster pcb?

[tishinator]

Hi there,

It has been a while since I have been on the forum.  A lot has gotten in the way of this hobby for me.  It is good to be back.  If I am asking this in the wrong place, please let me know.  I have no problem with moving it to wherever is the most appropriate.

At this point I would not call myself incredibly experienced.  I have built a couple of single transistor fuzz pedals, some cable testers, and when I was feeling adventurous I put together a pair of the runoffgroove "Umble" pedals.

I am planning on building a pedal that has both an AMZ mosfet booster and AMZ mini booster in the same box.  I intentionally want to have both as I am a fan of running multiple boosters into each other, and I would like the option of choosing one versus the other.  (Thinking of using some clever switching to be able to switch the order of the boosters on the fly, but this isn't about that.)  I am not familiar enough with the details of the AMZ "dual booster" PCB (http://www.muzique.com/schem/dual.htm) to know if this will allow me to build both on the same PCB or if I really need to get the separate PCBs for each one, or if some other PCB that Mr. Orman has will really meet my needs.  My concern is that the example schematics on the dual booster pcb site appear to show a single transistor, and the mini booster schematic has two on its own. 

The boosters I'm looking at are here:
http://www.muzique.com/schem/mosfet.htm
http://www.muzique.com/amz/mini.htm

I could just use perfboard and avoid the PCB altogether, but it appears that many folks use PCBs to speed up their build time and I would like to give that a try.  Up to this point I have wired everything using perfboard, and I can see the convenience of the PCB - less risk of my own error.

Has anyone had enough experience with the dual booster pcb to let me know if that will meet my needs?  Just trying to make sure my parts list is accurate before I go buy stuff.  Thanks in advance for your help, I appreciate it.

Thanks,
James

[Mark Hammer]

It's a little hard to be certain, since the posted picture only shows one side of the board.  But the legending certainly indicates room for up to 4 transistors, and the accompanying possibilities shown for what can be installed include both a mini-booster and a mosfet boost, so I think you're okay.  The challenge will be determining/deciphering wich pads to simply bridge with a piece of wire and which to install components into.

[duck_arse]

from the amz page:

This is a selection of just some of the circuits contained on the AMZ Dual Booster PC Board. The basic idea is to create a single pc board that can be used to make multiple projects, including boosters, overdrives and more.

Booster #1 and Booster #2 are totally independent and you can mix types of boosters from the schematic above. The most obvious use is to put them in series to use the first booster to overdrive the second boost.

the mosfet boost is circuit 4 or 5, and the mini boost is #6 on that page. the above quot suggests you can build any 2 of the six circuits on the one dual pcb, exactly what you want. although I've never seen the board itself.

(typing same time as mark)

[tishinator]

Thanks to both of you - I see that now you've pointed it out.  I think I was taking some of the diagrams to literally (like not seeing the section of the mosfet booster that surrounds Vr - the extra resistors & electrolytic cap).  Surely this is my lack of experience showing.

I think I was just missing the last diagram, or just not putting it together when trying to put the specific schematic for each into that generic context.  I see what you're saying now, they are darn near the same pattern just with some minor differences. 

Thanks for your help.  I'm glad to be getting back into this, I enjoyed it when I was able to build on a more regular basis before.  I'm looking forward to my first pcb experience, I think it will speed my build time dramatically.

Thanks again for your help, I appreciate this forum and the help I'm able to get here. 
James

[duck_arse]

I'd love to use printed circuit boards for all my circuits, but I'm stuck with vero, unfortunately.

good luck and let us know how you go.

[tishinator]

Just a quick update, in case anyone else runs into this.

Got my PCBs in the mail today and had time to check out the additional page that is set up for the technical details for the PCB.

The short answer is that it is possible to build something like the mini booster and mosfet booster, but the schematics are indeed different.  I am going to check with AMZ to find out if I am hosed (as I have already ordered parts for the mini booster and mosfet booster schematics shown above) or if I am being "too literal" in reading the schematics on the technical details page.

I'm sure this will work out fine, but recording my experience in case someone else finds themselves in the same situation.

[tishinator]

Well, after looking more intently at the options, what I can tell is that...

A) It is completely possible to build two mini boosters on the PCB, without any real parts modifications, if I am reading things properly.

B) It appears possible to follow the Mostfet Booster schematic, but I'm not sure yet on a couple of differences that I've emailed some questions on to AMZ.  I'm sure it is possible, but it may require more work than the Mini Booster. 

Lesson learned - when getting a PCB, do that first before ordering all the parts for schematics that you're not completely sure about.

[duck_arse]

that page of circuits has no part references, and the image of the board I can see is very small. but from looking at the board, it has all the spaces needed for parts to build two complete, nearly completely seperate, miniboosters. the mosfet booster 1 and 2 are just the lower half of a minniboost, and you link over the top fet until you get the resistors in the right places.

with a better picture of the board and traces, and which mosfet booster you wanted, I could work out component placings for you, but jack has probably done this somewhere at his site. I don't think you're hosed, you are good to go.

[tishinator]

Well, my combination was going to be a mosfet boost and a mini booster.  I was not completely hosed, but the circuits do have a small bit of tweaking to fit the dual booster pcb.

I worked out what I thought would work and emailed Jack, he was very cool about it.  I think that due to my current level of experience that my best bet is to suck it up and order the extra parts for the updates for the PCB.  If it were just for myself, I would probably get more adventurous with making them fit - but I'm making it for a gift and would like the layout to be extra clean.  Really, most of the excess parts I can use for other future projects, so no harm done (other than to my pride).

[duck_arse]

I'm getting more confused as we go on. what parts did you get first (a miniboost set and a mosfet boost set?), and what parts do you think you need now?

[tishinator]

Sorry, didn't mean to cause any confusion or frustration for you.  To clarify, I think I am in a good position at the moment.  I am just documenting my experience here in case someone ever searches for this so that they can benefit from my learning experience.  I did not mean to be unclear, I've been fairly busy lately and have been sleep deprived for some time now.

Here is a summary.

1.  I bought the parts for the stock schematics for both the mini booster and the mosfet booster AND I bought the dual booster PCB from AMZ.
2.  Upon purchasing the dual booster PCB from AMZ I received a link that described the various boosters that work with it, and promptly realized that the schematics were close but not exactly the same.  At this point I freaked out a little (see the sleep deprived comment) and thought I was hosed.  (That was rash and unfounded and posting that was probably not the smartest thing I've ever done in my life.  In reality I am not hosed.)  This 'buyers' site is the missing piece.  It has additional schematics with intentional variations on the stock schematics - each stock schematic includes their own type of power filter, and the mosfet booster has a network of resistors & capacitors called a "voltage divider" that appears to cut the power in half.  (I only know enough to be dangerous, at some point I will learn more about what the portions of the circuit are actually doing.)  The dual booster 'buyers' page has very similar circuits but different parts (more variation in the mosfet booster) to work with a single power filter section.  It appears the differences are partially to "bias" the mosfet (like a tube?) given the different power structure.  None of the schematics are on the 'buyers' site are exactly the same as the stock ones I linked to initially.
3.  I spent some time with the updated schematics from the technical information from the 'buyers' site for the dual booster PCB and each of the schematics that I bought parts for to identify the differences, and sent an email to AMZ about those differences to see if it would be simple or complex to incorporate the stock versions of the schematic using the PCB.  (I'm sure that simple or complex are in the eye of the beholder.) 
4.  Jack was very cool, and after assessing my experience he noted that both circuits need subtle tweaks when put onto the same board. 
5.  I realized that if I had been doing this on a more regular basis, I would likely have the skill set to make the original circuits work.  I was glad that I could use the original schematics to work out how (or at least to see the differences).  However, I also noticed that for a trivial amount I could just save myself some time and trouble by going with one of the proven variations on the 'buyers' site.  I whipped up a quick inventory of parts using the 'buyers' site and compared that to what I bought and I have most of what I need to build the variations that work with the PCB.
6.  While I recognize that doing what I originally wanted to do (using the stock schematic for each circuit on the board) is completely possible, I also saw that there is wisdom in going with a proven version.  One of the advantages is having something cleaner / clearer to debug.  I'm doing a few other "new" things for me with this build (trying the TTG light plate, those things look really cool) so I wanted to do everything I can to increase my chances of success.
7.  To make my life simpler I just ordered the small number of extra parts (to build the exact circuits on the 'buyers' site) and chalked it up to a life lesson.  (I have enough to build two, so I may still try my own experiments on the one that is not a gift and that doesn't have a deadline for the finished build coming up fast.)  I wasn't trying to disregard your offer for laying out the components, I made that decision for other reasons.

I am not in trouble at all, just wanted to document what happened for future generations of dual booster pcb users.  I think that this reflects more on my learning experience than anything else, and I think quite highly of AMZ, you, Mark, and Aron for setting up this forum for this sort of dialog.

[duck_arse]

ok, all clear now.

I recommend you read everything you can find on jfet boosters, mu-doublers, mini boosters and mos boosters at both amz and geofex. they will explain biasing and how these circuits work.