PI front end Opamp

[Mdtoday]

I have recently been testing a few Opamps suitable use in my updated PI design (I'll post when complete).
Ended up settling for the OPA1611 from TI which works well.
Used with non inverting gain of 63 and +/- 5v supplies.
For anyone interested, it might be worth a look.

http://www.ti.com/lit/ds/symlink/opa1612.pdf
cheers

MDtoday

[6666]

I think I still have some of those in the junk box, will be interesting to try them out.

[liudengyuan]

good

[eclipse]

Opa1611 is replacing lme49990 which have been quite popular and for example used in the early QED designs.

[liudengyuan]

I think that an excellent pulse detector needs to solve many problems. The low-noise preamplifier has certain advantages, but this is not the key point. The focus is on zero drift and temperature drift problems. The factors of pulse detector instability are The most important is coils and FETs, and you want a highly stable machine. We must solve the FET instability, or add an automatic control circuit to the preamplifier. To deal with the drift of components,

[dbanner]

Don't forget fast coil field switch off.

[liudengyuan]

In all diy detectors, the delta pulse design is reasonable, and of course there are disadvantages.

[liudengyuan]

Only known to have fast recovery diodes, no fast FETs were found

[kt315]

delta pulse eliminates the drift of frontend in start of every cycle of measuring. High Slew Rate: 27 V/us is low for delta pulse, we wait >50 from TI.

[liudengyuan]

Is there a FET that is more stable than irf740? Please express your opinions

[6666]

Is there a FET that is more stable than irf740? Please express your opinions

Whats your definition of stable ?

[liudengyuan]

If you measure with an oscilloscope millivolt, you will find that the signal from the coil is unstable, and it is constantly beating and drifting, so the preamplifier follows and drifts.

[kt315]

Is there a FET that is more stable than irf740? Please express your opinions

very amazingly to get the question from men living in country that does all electronics in the world.
we (WE) have to get this info from you.

[dbanner]

If you measure with an oscilloscope millivolt, you will find that the signal from the coil is unstable, and it is constantly beating and drifting, so the preamplifier follows and drifts.

Could you please explain in more detail.

[liudengyuan]

hi