Surf PI 1.2 - Big Jitter on pin 1 of LM358. How to get rid of it?

[Polymer]

What does the signal look like on pin 7 of the LM358?
I assume the voltages on pins 8 and 4 are stable?

They look stable now. Is ist okay that -voltage is not quite as much as +voltage (-4.2v to +4.9v)?

Screenshot of DC +- 5v Pin 4 +8 LM 358

Signal Pin 7 of LM358:

[ionut_mtb]

They look stable now. Is ist okay that -voltage is not quite as much as +voltage (-4.2v to +4.9v)?

Screenshot of DC +- 5v Pin 4 +8 LM 358 [ATTACH]40518[/ATTACH]

Signal Pin 7 of LM358: [ATTACH]40519[/ATTACH]

Original surf pi have same reading. my homemade surfpi, same. -4.2 +5v

[Polymer]

POLYMER, do you have any battery powered analog clocks in the house ??
i experienced similar problems a few years back,
took battery out of clock !!

instantly allot better,
1 second pulse from the analog clocks coil !!

i live in a semi-detatched, could still detect neighbors kitchen clock, dang !!

deff worth syncing the 7660...........

just my 2 peneths worth

Thank you for this hint DOOLEY!
That reminded me of of what I did round 25 years ago: making pulses from a battery operated analog wrist watch audible.
The pulses sounded like gunshots ... I don't wear watches anymore, so couldn't say if that would annoy my PI.

We do have two battery operated clocks in the house - without power for now. Will play around to see just how annoying they are for a PI.

[Polymer]

Original surf pi have same reading. my homemade surfpi, same. -4.2 +5v

Thank you for the verification of the voltages ionut_mtb!

Hope we don't both have it wrong

[Polymer]

Update:

I found I somehow don't like the 7660's (had too many hassles with them on Baracuda & Surf),
so I put in a LT1054 according to specs of datasheet
using it as a Voltage Inverter/Regulator from 12v.
It works well and I also have nice symmetrical +-5v rails now.

[Qiaozhi]

Update:

I found I somehow don't like the 7660's (had too many hassles with them on Baracuda & Surf),
so I put in a LT1054 according to specs of datasheet
using it as a Voltage Inverter/Regulator from 12v.
It works well and I also have nice symmetrical +-5v rails now.

This fact is already mentioned in both the MPP and Geotech Baracuda Build Documents.