Re: strange 29 Hz spike

[Guest guest]

Hi Pete --

I am using the Pendant, with the snap in leads. When I first saw the

spike, I did check for 60Hz interference, but did not see anything

there. I saw the spike on one child, but when I moved the same leads to

another child I didn't see anything. I will retry another time on child

1 to see if the spike reappears.

I am sure this is some sort of interference, but I have just never seen

it at 29 Hz before. Here is one more strange data point. When we

noticed the spike was more prominent in the back of his head, the kid

said " Lets see what happens when I turn around. " . When he turned his

back to the receiver, so that the lead was closer to the computer the 29

Hz spike attenuated, but was still there. Maybe there was something

coming from the wall behind him.

Theresa

Van Deusen wrote:

> Theresa,

>

>

>

> The 29 Hz spike does sound strange. What amp are you using? 29

> sounds suspiciously close to half of 60. If you did have a strong

> spike at 60 Hz of electromagnetic interference, you could get a first

> sub-harmonic spike at around 30. Did you use the same hookup, just

> unplugging one child and plugging in the next then back to the first?

> Try changing the connection, changing the electrodes, etc. and see if

> it persists.

>

>

>

>

> Also one other question ... neither of my test subjects had much

> activity at all above 20 Hz. I assume this is normal. However, the

> boy

> had a prominent spike at 29 Hz ... I never saw this before. The spike

> was high at Pz, and smaller at Fz, but still present. I moved the

> lead

> back to Pz and it got strong again. The spike did not show up on my

> daughter, who was sitting in the same location when I tested her. Any

> idea of what might cause a spike at 29, but only on one individual?

>

> .

>

>

>

>

> --

> Van Deusen

> pvdtlc@...

> http://www.brain-trainer.com <http://www.brain-trainer.com>

> 305/433-3160

> The Learning Curve, Inc.

>