Hi Chris;
       I see that you are still giving out great information and advice. 
Could you possibly " point" me to the schematic of the serial AS-1 
period "extender". As I recall I built the Roberts circuit years ago 
with limited success. I'm pretty sure I did not get the component values 
correct. I will try the Roberts circuit again after I try the AS1 
"electronics". I searched for the AS1 schematic/detail but only found 
very general info on it. I haven't "played" with this "stuff" for years 
but I feel a very strong resurgence of interest in Seismology since I 
started this project again.  Thanks, Ed.



On 9/17/2012 5:22 AM, chrisatupw@....... wrote:
> Edward Ianni 
> To: psnlist 
> Sent: Mon, 17 Sep 2012 0:53
> Subject: Old hobby resurgence
> Hi all:
> I have two very old seismometers and I would like to extend their 
> "periods", electronically and EXTERNALLY if that is possible. I tried 
> this a long time ago but I am not heavy into electronics and could not 
> come up with the right values for some of the circuits that I looked 
> at. The two Seismometers are a Kinemetric SH1 "Intermediate"(about 5 
> second period), and a Sprengnether (square box type) with a 1.5 second 
> period. Is it possible to do this easily and is there a circuit 
> somewhere with relatively simple instructions for calculating 
> component values? Thank You. Ed.
> Hi Ed,
>     The short answer is Yes !
>     You can extend the period of a seismometer electronically by about 
> x10 with two stages of the parallel Robert's circuit, or you can use 
> the simpler serial type used in the AS-1. So the Sprengnether could 
> easily go out to 15 seconds and bring in the surface waves fairly 
> respectably. I suggest that you extend the SH1 only to about 25/30 
> seconds and this is a bit more difficult since you may have to 
> suppress 1/f noise. You have the problem with requiring a 1/f^2 
> amplifier characteristic and this gain has to go to periods beyond 
> what you require and the excess 1/f noise has to be filtered out.
> Regards,
> Chris Chapman


  
    
  
  
    
Hi Chris;

            I see that you are still giving out great information and
      advice. Could you possibly " point" me to the schematic of the
      serial AS-1 period "extender". As I recall I built the Roberts
      circuit years ago with limited success. I'm pretty sure I did not
      get the component values correct. I will try the Roberts circuit
      again after I try the AS1 "electronics". I searched for the AS1
      schematic/detail but only found very general info on it. I haven't
      "played" with this "stuff" for years but I feel a very strong
      resurgence of interest in Seismology since I started this project
      again.  Thanks, Ed.

      

      

      

      On 9/17/2012 5:22 AM, chrisatupw@....... wrote:

    
    

        
Edward Ianni <edwianni1@...........>

          To: psnlist <psnlist@..............>

          Sent: Mon, 17 Sep 2012 0:53

          Subject: Old hobby resurgence

        
        
Hi all:
                      
        
I have two very old seismometers and I would like to
            extend their "periods", electronically and EXTERNALLY if
            that is possible. I tried this a long time ago but I am not
            heavy into electronics and could not come up with the right
            values for some of the circuits that I looked at. The two
            Seismometers are a Kinemetric SH1 "Intermediate"(about 5
            second period), and a Sprengnether (square box type) with a
            1.5 second period. Is it possible to do this easily and is
            there a circuit somewhere with relatively simple
            instructions for calculating component values? Thank You.
            Ed.
        
 
        
Hi Ed, 
        
    The short answer is Yes ! 
        
    You can extend the period of a seismometer
            electronically by about x10 with two stages of the parallel
            Robert's circuit, or you can use the simpler serial type
            used in the AS-1. So the Sprengnether could easily go out to
            15 seconds and bring in the surface waves fairly
            respectably. I suggest that you extend the SH1 only to about
            25/30 seconds and this is a bit more difficult since you may
            have to suppress 1/f noise. You have the problem with
            requiring a 1/f^2 amplifier characteristic and this gain has
            to go to periods beyond what you require and the excess 1/f
            noise has to be filtered out.
        
Regards, 
        
Chris Chapman