How to get a Firefly schematic?

[Paul Marossy]

Anyone know where to get the schematic for the Firefly? I tried going to Doug's site, but they won't come up when I click on the links....

[Mike Burgundy]

I'm sure Doug's just messing about on his site and it will be sorted soon, but if you can't wait I have a copy somwhere. Mail me if you want me to dig it up.

[Ansil]

how about a layout for the firefly.    anyone have one.  somethingl ike      stuart's plexi layout.

[Mike Burgundy]

I also did one of those *rummage rummage*
see if I can find it...

[Ansil]

I also did one of those *rummage rummage*
see if I can find it...

cool cool

[Travis]

http://www.missouri.edu/~lnra54/FireFly_sch.gif

[Doug H]

As you guessed, I'm in the middle of doing some mods to my site. I accidently re-named the schem files before I put up the link page. I'll have the mods done in a few days.

For now, here are the links:

http://home.cfl.rr.com/dbhammond/Firefly_sch_R1.gif

http://home.cfl.rr.com/dbhammond/Firefly_sch_R2.gif


Doug

[Paul Marossy]

Thanks, Doug.  

[Paul Marossy]

Does anyone have a PCB layout for this one? I am interested in the boost version. I may build it just for kicks.

[Ansil]

Does anyone have a PCB layout for this one? I am interested in the boost version. I may build it just for kicks.

if you do let me know. i would like to get a pcb for this.  or at least some sort of layout as i suck without an auto router

[Doug H]

Someone at ax84 (can't remember who ) sent me this turret board layout they did for it. They included the resonance control from the original schem with the boost version. I have not verified this but at first glance it looks ok.

http://home.cfl.rr.com/dbhammond/firefly_layout.jpg

Doug

[Paul Marossy]

Thanks, Doug.
Anyone have any tips on where to get the transformers? Mouser?

[Doug H]

Thanks, Doug.
Anyone have any tips on where to get the transformers? Mouser?

Antique Electronics and Angela Instruments usually have the best deals on hammond iron. I have bought a lot of stuff from Antique and have been very happy.

You don't need to use a separate filament and power transfomer if you don't want to. I did because I could do it surplus and keep it cheap. Hammond makes a 190-0-190 transformer that will work fine for this circuit. It has the filament and power windings in one package and will save you some real estate on your chassis. In that case you don't need a 4-diode bridge for rectification either, just use 2 diodes and ground the center tap of the power transformer. (My transformer is not center-tapped so I had to use a bridge.) Check the ax84 P1 schem for reference on how to do that.

Can't remember the model # but the ax84 guys use it for the P1. It will be 10-20V lower on the plates, but if you want to run the 12au7's a little hotter just reduce the 560ohm cathode resistor a little. I don't suspect it will make a big difference soundwise either way.

Just keep the power dissipation on the 12au7's below max spec, 2.75W if I recall correctly. If this is your first foray into tube circuits and/or you need help with this kind of stuff, start by checking Randall Aiken's site and read the tech section. It has very good info about biasing and calculating power dissipation among many other things. I invite you to come over to the ax84 forum and ask questions over there. There are many FireFly builders there and many helpful people that can help you get started.  High-voltage tube circuits are a different world than stompbox pedals and there are different considerations you have to make. (If you're already familiar with all this stuff, ignore what I just said. )

Doug

[Paul Marossy]

Well, I am familiar with tube stuff, but not enough to design my own stuff.
I learned a lot by reverse engineering my Seymour Duncan Convertible and most of all of the modules that were available for it. I built several of the modules myself, designed some PCBs, made layouts, etc. The pages I wrote up on this amp can be found at my website under Guitar Amps.

Anyhow, it's kind of fun messing around with tubes. This Firefly project looks like a simple enough project for starters. Sometime, I would like to buy one of those Allen Amp kits and build it myself. Money and time are my two biggest enemies right now...