Power booster : tips for decreasing noise

Thread Starter

Bobbylabidouille

Joined Nov 16, 2014
1
Hello everybody, here my first post!

I have a problem with an analogic circuit. This circuit works but, while working, it creates too much noise ... I would be glad to get some tips in order to improve it!

The input signal is a potential sweeping from 0 to 5 V (NI-6009). This potential is applied on a load (Resistance, electrochemical cell etc...) and then current is recorded through a resistance. The circuit helps the NI-6009 to sustain power in the range of 0,5 W to 1 W.

exportV3.png

I carried out experiments with a 10 Ohm-load, I obtain standard deviation of the input signal of ~ 100 mV and the aim would be, if possible, 10 mV.

I managed to reduce the standard deviation to 60 mV in inserting capacitors between the bases and the emitters of the transistors, but I don't really know what to do...it is above my competencies...

Does someone know what I should insert and where in the schematic above?

Many thanks by advance!
 

GopherT

Joined Nov 23, 2012
8,009
Put some large caps across your four power supply sources (2 x 5v and 2 x 12v).

Also, TI advertises the tL 071 as a low noise version of the tL081. Both are fairly old. Newer, lower noise op amps with the same pin-out are a ail able from TI.
 

GopherT

Joined Nov 23, 2012
8,009
Feedback cures all if his transistions are slow enough, oops, he has a noise issue - time for a better amp design.
This is a good option - middle option in RonV's link.
 
Top