Build a (Tayda) RAT.

[italianguy63]

I also have a mini 1590A version too.

Truly a Rodent of Unusual Size.

The little one!

[Ben N]

The little one!

And all thru-hole! That is insane! Kudos, and I won't be trying that.

[bamslam69]

I built a Tayda Rat a couple of years ago.  I made it with all of the correct values.  I installed a 12 position rotary switch with all of the diode clipping options I could thing of.  The first position is without clipping diodes.  It makes a really good clean boost.  My Rat pedal is one of my favorites.

Actually going to do something similar, but thinking about using a DIP switch arrangement, so you can add in whatever clipping arrangements. Dumb move?

[iainpunk]

i think that dip switches can be really cool for inside a pedal, but another thing that impacts clipping a lot more that people realise is the 1k resistor before the signal hits the diodes. on my breadboard, i used a 5k trimmer and a 330 ohm resistor in series, to change the curve/knee and the treble amount in the distortion, going from bright and hard to softer and darker.

cheers

[bamslam69]

Finally built my RAT, but just from the layout on the tagboard effects site. I added the 8 switch DIP board for diode clipping, and currently have it set at some random red LED's.
The thing sounds wicked! Can't wait to give it a run at band rehearsal.

[iainpunk]

has anyone done a cmos rat yet? i think an opamp driving a cmos gainstage into distortion would be cool.
to match the amount of distortion created by diode clippers, and to keep the opamp in control of the frequency spectrum, the gain of the CMOS inverter stage should be low, like really low. i think between A= 5 and 10, quick and ditry calculations say 7.

cheers

[Ben N]

has anyone done a cmos rat yet? i think an opamp driving a cmos gainstage into distortion would be cool.
to match the amount of distortion created by diode clippers, and to keep the opamp in control of the frequency spectrum, the gain of the CMOS inverter stage should be low, like really low. i think between A= 5 and 10, quick and ditry calculations say 7.

cheers

That sounds cool, but what is Rat-like about it?
I'm pretty sure peeps have built Rats with a CA3140, so that's one way to get CMOS goodness in a RAT.

[iainpunk]

has anyone done a cmos rat yet? i think an opamp driving a cmos gainstage into distortion would be cool.
to match the amount of distortion created by diode clippers, and to keep the opamp in control of the frequency spectrum, the gain of the CMOS inverter stage should be low, like really low. i think between A= 5 and 10, quick and ditry calculations say 7.

cheers

That sounds cool, but what is Rat-like about it?
I'm pretty sure peeps have built Rats with a CA3140, so that's one way to get CMOS goodness in a RAT.

what makes a rat a rat is the frequency response of the opamp and its negative feedback loop. using cmos in the way described doesnt change this, as it has the same ''relative gain'' as diodes would have.

CA3140 isn't cmos, its bipolar for the most part, but uses 2 input mosfets, AKA Bi-MOS. you want the 3130 or 3160 for that.
just substituting the 308 for a cmos or bi-mos opamp, where it has its cmos gain stage inside a strong feedback loop and still utilising diode clipping, is wildly different than replacing the diode clipping with cmos clipping.

cheers

[PRR]

...CA3140 isn't cmos, its bipolar for the most part, but uses 2 input mosfets, ...

Correct. An odd old duck.