AMZ (Jack Orman) Mosfet Boost (aka HBE UnoMos)

[johnk]

here's a great sounding mosfet booster. I drew up two versions. one with a buffered bypass and the other with a true bypass. BTW, it works great on both guitars and basses. both are VERIFIED.

[GeGhostRider]

hi Johnk,
thank you for all your contributions to this great site.
I was planning to build this booster using your true bypass layout but I'm wondering about the 1M resistor; shouldn't it go one row up for ground connection?
thanx again

[johnk]

yep. it should. FIXED sorry about that.

[peavey_xxl]

For some reason this one is giving me fits.   I have adjusted the 62k with no luck changing the bias on the drain.  

[BetterOffShred]

So I built this real quick, and put a 2n7000 in it (flipped to match DSG orientation ) but I don't have a 9v1 zener.. I think they are 1n4739 or something.. so I tried a 15v zener and nothing.. tried a 1n4001 as another layout for this effect indicates will work.. nothing. . I've built quite a few effects so far and I'm fairly sure everything is hooked up correctly and I knifed everything, so I'm thinking I just need the correct diode in there for it to work.  Will this layout work without that 9v1?

-Brett

[nocentelli]

It should still work without the diode.

[BetterOffShred]

Yeah I'm going to just rebuild it, it works intermittently if I prod certain areas of the board.. I'm not sure about my 2n7000'situation either. I appreciate the input man. Thanks.  In the meantime I built the other one, tiny boost or whatever. It sounds great too. I've been rediscovering the glory of boosts in front of my '68 Bassman I finally got going. They really bring a whole new dimension.  Thanks again
-Brett

[Pedalhead]

I’ve built a couple of these. Great circuit. I use mainly single coil pups and they’re useful to up the gain (without effecting the tone too much) of pedals that prefer humbuckers. On my builds I’d say the signal gets slightly brighter going through them, but pretty close to a flat frequency response. I coupled one with the AMZ Presence Control to make a tone boost, one of my first pedal builds.

[BetterOffShred]

Yeah I rebuilt it and it works great with the 2n7000 now.  It's super quiet too, I really like this one. The mini boost seems to add a little 'fatness' to the sound comparatively, but I like this for straight boost.  I also built the Smalley NPN boost real quick last night, and that's pretty cool too. I tried it with a few different trannies and I found the 2n2222 to be the most headroom and least breakup, but it still adds some grit as you turn it up.  Cool boosts.
-Brett

[Dreadneck]

Hi!

I know this post is old now, but where there is hope right? ;)

I've tried to build this pedal from your layout (the right one, true bypass boost) but can not get it to work..
As far as I know I've followed the layout and instructions correctly.

There is sound when the pedal is off, but nothing when it's on. The LED lights up when I turn it on aswell, so I don't think there are any issues with power.

Though I am confused with the switch and output from the circut board. I have looked it up elsewere and everyone has completeky different versions of the same pedal.

[PMowdes]

Post a new thread in the debugging section.

You need to included some pictures of your board (top and bottom) and voltages if you are able to measure them at each leg of each of the transistors.

Someone should be able to help

[Matlevo12]

Please someone, correct that image.
The 1M pulldown resistor should go between the 1st row (in) and ground, not from the 3rd row, like it's said on the second post.
This setup WON'T WORK, and most likely HAS NOT BEEN VERIFIED please correct it!
It's the first veroboard image that shows up when you're looking for Jack Orman Mosfet Boostee on google image, this is going to mislead a lot a people!

[amsterdam]

the 1M resistor can be removed all together. It is most definitely in the wrong place in both layouts. http://www.muzique.com/schem/mosfet.htm

[Matlevo12]

It's not in the original schem because it's a pulldown resistor you can add to avoid pops.
Can be useful if you don't want to chase leaking caps, but it goes between the board input and ground, not after the first cap. I did test it because I was too lazy to double check the layout, it didn't work.