I've started to play with this circuit which uses a TL431 has a super transistor, it is a beast in fact. Does anyone played with the tl431 to make a booster. It doesn't seem to be very common in guitar stompboxes.
(http://www.diale.org/img/bboost.png)
The first part is just a buffer to drive the tl431.
Any comments/sugestions? Similar projects?
Cheers.
Refs.: http://www.techlib.com/electronics/audioamps.html (http://www.techlib.com/electronics/audioamps.html)
1) As always...any sound clips?
2) Any controls involved?
It is just a VERY BIG clean boost. No controls.
Quote from: tca on April 20, 2012, 01:02:17 PM
It is just a VERY BIG clean boost. No controls.
Like...how big?
Well... bigger than: a SHO at full gain, a MPF102 minibooster, ...
With R5=180, current consumption is a beast. If you ever run battery, it should work nearly the same with R5=5K or so.
> first part is just a buffer to drive the tl431.
Actually to drive R3 coming back from a gain of -300, acting like ~~1.5K. The JFET is straining to wiggle against that. This is probably a Good Thing. If not straining it would probably sound a lot like an opamp.
Interesting use of a part specified for other work.
Hi PRR, nice to ear from you again.
I've tried with diferent values of R3; R3=5K will work but frequency response changes and a different value of C2 is needed to compensate the change.
Hey tca, I made something similar (the idea came from the same site you linked by the way...) but without the input buffer and with a diode as a clipper on the output (I wanted to make an overdrive). I posted a schem on the other site.
The real funny thing is that it can drive a speaker too.
Quote from: allesz on April 21, 2012, 06:47:00 PM
Hey tca, I made something similar (the idea came from the same site you linked by the way...) but without the input buffer and with a diode as a clipper on the output (I wanted to make an overdrive). I posted a schem on the other site.
The real funny thing is that it can drive a speaker too.
Just found your entry on the other side... and forgot to post my headphone amp with the TL431.
(http://www.diale.org/img/headphoneguitar.png)
It partially solves your problems of extra gain, and indeed it can drive a 8Ohm speaker.
Cheers.
Volume pot is wired unusually.... is that how you want it?
Quote from: PRR on January 25, 2013, 09:17:31 PM
Volume pot is wired unusually.... is that how you want it?
Yes I know, it makes the tone control working much better than the usual setup for a volume pot.
some images lost, so I'll repost what I have.
beastboost.png
headphon.png