PI settling time

[GT Blocker]

Hey all.
I wondered if the settling time on my HammerHead is due to warm-up time for components or what. It seemed that when I changed from the TL082 to an LPM7716 that the time for the circuit to stabilize increased (although I like the 7716 better, so it's no big deal in the long run).

By 'settling time'. I mean the time from start-up to a stable and clean waveform at TP4.

So the question is: What factors are in play here?

Hope the question makes sense...thanks, GTB

[joecoin]

How long is it taking for the waveform to settle?

Got a picture of the waveform?

[GT Blocker]

clocked times

Hey Joecoin,

I measured 35sec for my LME49710/LMP7716 combo as opposed to 30sec for the original NE5534/TL072 stock setup. Same with the TL082, not much of a difference.

I posted the waveform in my TP4 thread in the HH project forum a while back and it still looks the same in either of these configurations. The consensus in that post was that the waveform is fine. Here's the link to that thread:
http://thunting.com/geotech/forums/s...ad.php?t=14469

Do these times seem longer than they should be? If so, I wonder why....

Thanks, GTB

[homefire]

GT:

I would think the coil it's self would be the major player.

Warming up is going to cause machanical as well as electrical variations.

Just my Thoughts.

[GT Blocker]

Hmmm

Good point, homefire...

I'm wondering if the settling time is due to metal objects and EMF in my WAY over cluttered 'lab'. I figured there should be some warm up time for the components, but 30+sec seemed a bit much. I'll have it boxed and on a 'stick' by the end of the week, so we'll see how she behaves outside then.
I picked up a NEW "Treasure Hunter All Vision Pro" on Ebay for $20 just for the mounting rod (now THERE'S a piece-o-crap detector, Pro my arse!). For that matter, if anyone wants the coil and control box for 10 bucks plus shipping, PM me. I can't believe they claimed that thing retails for just under $400! LMAO. The mounting rod is nice tho....
Anyway, I'm getting off topic, laters.

Thanks!

[gef12]

hi
Have you noticed any difference in performance other than the settling time .. I am currently using tl052... and was trying an AD version (forget the number as i speak ) and that was a tad better ...
your thoughts
cheers

[joecoin]

Throw the coil in the freezer for an hour, after taking it out of the freezer fire it up and time it.

[Tinkerer]

Settling time

Check your power supply.

Tinkerer

[GT Blocker]

Mystery solved...

An update on the settling issue.

As time has gone by the problem worsened and I noticed that (HHvD1) IC1 & C3 were getting noticeably warm as well (I know, "Check your power supply.Tinkerer", but that seemed fine then).

Turns out that C27 (in the DC offset) was failing (bad from the start, more or less, and now shorting out). After replacing C27, instant starts/no settling time, mystery solved, whew.

My thanks to all of you who pitched in trying to figure this out!
GT Blocker

[homefire]

Crazy Stuff. With exception of electrolitic type, I've never seen one fail. Must have been bad from the start like you said.