I'll add my 10 cents here. Because the accumulation time can be very long 555 class timers become a serious issue due to the large R&Cs involved. I will guess some accuracy is desired. As Chris says a start button to an arduino. The difference I might suggest is a GPS 1sec PP into the arduino for counting. Then through a serial port you could input what ever accumulation time you might like. Using a 64 bit integer thats a lot of seconds that are quite accurately timed and semi-traceable to real time for events. Have fun. Curious what you are counting? Regards Paul WB8TSL
On Tue, Nov 15, 2016 at 7:47 PM, Scott Stobbe <[email protected]> wrote: > If you are trying to avoid writing code, the 74hc5555 might be worth taking > a look at. > > On Tue, Nov 15, 2016 at 3:00 PM Chuck / Judy Burch <[email protected] > > > wrote: > > > > > I'm building a laboratory scintillation counter that uses my HP 5335a > > counter as a read-out. The FREQ mode gives only approximate results > > (maximum gate time is about 5 seconds). The TOT mode counts pulses for > > an arbitrary time that can be set using the "external arm input" on the > > rear panel. So I need a timing pulse (of either polarity) of known and > > adjustable width (time). One way to do this is with a PIC frequency > > divider taking the counter 10MHz output down to 1 PPS following that > > with two or three ripple counters to get a 1 - 5 - 10 - 50 ... > > sequence. That I understand. > > > > How do I get a pulse to start with a push button and then stop for > > example 500 or 10,000 seconds later? > > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
