"fetzer valve amp" schematic....

[casey]

does this schem. look right?


any improvements?


i'm working on a tube amp version......  should be cool.

http://www.freewebs.com/outofbrokeness/circuits.htm

[Eric H]

You might want to add an "output" indicator

I'd make the dc filter cap (2,2uf) larger --47uf to 100uf .

-Eric

[Lonestarjohnny]

and maybe a Master Volume so you can control the gain and volume, also shielded input and output wire would help keep thing's a little quiter.
Also on the Fetzer Circuit they forgot the 100uf filter cap on your 9 v. input,it should be axial or radial with the plus side of the cap going to the battery.
JD

[casey]

ok, ill try that out j.d.  
it'll take me a few seconds....

hey erik,

thanks...how's that look...

[casey]

how do i control the volume of the output stage without putting a rheostat
at the end of the circuit?

[Eric H]

ok, ill try that out j.d.  
it'll take me a few seconds....

hey erik,

thanks...how's that look...

Great --add another R/C filter to the preamp 9v input (or run a line over to the TDA input).

-Eric

[casey]

cool, im on it...

[Lonestarjohnny]

You could also do a Fender style Bass & treble tone stack somewhere there at your volume pot if you wanted to.
JD

[spongebob]

Personally I like the idea of using FET emulations as the preamp stage for chip power amplifiers, I connected  the runoffgroove "Eighteen" to a TDA2050 (~30 watt) chip, into a 12" speaker, killer sound! I wonder why commercial manufacturers insist on using opamps/diodes for distortion in their SS amps...

Oh, and if you really want 8 watt output you should increase the supply voltage a bit!

Nice page with tonestacks:
http://amps.zugster.net/articles/tonestacks/

[casey]

will the j201 handle 12v, cause if so, then i can just put them
both up to 12v....i just didnt want to because of the convenience
of one power supply or the easyness of the circuit...

thanks.

[spongebob]

yes, not sure what the limit is, but 12V will definitively do no harm, even 20V would be ok, I think.

[petemoore]

Make sure your capacitor voltage ratings exceed the power supply voltage.

[casey]

cool.

[Lonestarjohnny]

Casey, the J201's are rated to 20 V., but the higher voltage you run them the hotter they get and that mean's for every 10 degree's hotter you can double the ta draw, so if you loose 1 you might have to heat sink them or back down on the voltage some, you got a nice build going, let us know how it turn's out, I've got to where I can't stand my PV without the Fetzer being turned on all the time, it give's the tone and the extra gogettum that my amp don't got.
JD

[changes]

would any other chip do?
like 4558
or TL072 etc...

[Eric H]

would any other chip do?
like 4558
or TL072 etc...

The tl072 is very similar in specs to a LF353 and would work well here.


-Eric

[Prive]

would any other chip do?
like 4558
or TL072 etc...

The tl072 is very similar in specs to a LF353 and would work well here.


-Eric

Sorry guys, the TDA2003 is a 5 pins power amplifier with 10W at 15V, it isn't TL072 or op-amp replace.

Saludos, Marcelo.

[changes]

the output should go between the .1uF cap and the 1ohm resistor correct?

really cool i would like to see some other schems of amp clones like this....

[casey]

i have made some minor refinements to the circuit.

http://www.freewebs.com/outofbrokeness/circuits.htm

Now off to a tube version......

i'm going to need some help on this one folks.....

[Eric H]

would any other chip do?
like 4558
or TL072 etc...

The tl072 is very similar in specs to a LF353 and would work well here.


-Eric

Sorry guys, the TDA2003 is a 5 pins power amplifier with 10W at 15V, it isn't TL072 or op-amp replace.

Saludos, Marcelo.

Haha...that's what I get for responding to more than one post at a time.
Cheers, Marcelo

-Eric