On 7 Nov 2007 at 11:03, Steffan Heydon wrote about :
Subject : Re: [microelectricitygermkiller2] R

>
> Hi Tony,
> The URL for the 9V batteryvoltageamplifier 9 + 18, +25, +33V is below.
> I just realized the link I provided did not take you to the actual
> page.
>
> http://www.geofex.com/circuits/+9_to_33.htm

Yes an interesting site And didn't find that but figured out the gremlin; will
do next time i'm on
line. Thanks.

>
> Rather than switching the output jack, I think I will just use a small
> push-to-make switch in order to manually switch the LED test circuit.

Yes, a good move. leds use a lot of power in that circuit. Anyting to make it
micropower
would be good.

> I take it the zener diodes are just to run the LED as the zener
> diodes, the LED and the 22 uF cap were removed from your modified
> circuit?

Huh? My modified circuit? My own circuits are in pencil in a little book here
and right now I
can't find the book.

Hmm, its a while since I designed on this. think you needed higher value Z's for
the higher
supply voltage, so you probably right. Take care not to exceed the opamp specs
or they will
fade on you.

>
> So you are saying to add a 2.4 mega ohm resister between pin 2 and the
> 0.1 uF cap? This will change the frequency 1/60 hertz or every 30 sec?
> You have found this to be more effective than the 8 hertz setting?

No, i didn't say that. . The published circuit that i worked from had those
values and that goes
at nominal 4Hz. You will have to try altering those values to get what you want.
I personally
had the feeling that the older design of about 1Hz was more effective but have
no way of
being categoric about that. Also I battled to get the signal to be symmetrical
at slow speed.

Have fun,
Tony



>
>
>
>
> Blessings,
>
> Steffan
>
>
>
> On Nov 7, 2007, at 10:23 AM, Tony Moody wrote:
>
>
>