Diagram of the two opto couplers? In a message dated 7/25/2013 4:10:54 P.M. Eastern Daylight Time, paulsw...@gmail.com writes:
Bert pretty sure he is just asking for a diagram. He is interested in the method of noise isolation. Regards Paul. On Thu, Jul 25, 2013 at 3:32 PM, <ewkeh...@aol.com> wrote: > I do not understand your question, I am referring to low noise applications > like counters for dual mixers or other AV measurements, but also Shera and > even Tbolt where external noise should be kept to a minimum. When you > chase 1 E-14, isolation is key and I always like to err on the cautious > side > and as I stated we use blue tooth or USB but in the case of USB there are > always H11 in the circuit. Some still like to use RS 232 and the subject > came > up and I have on my boards H11's like on the counter Corby uses but he > ended up using an external power source and I like to eliminate that > requirement. David had the right answer using the power that the RS 232 > mouse uses > out of a DB 9, started looking but I do not have one any more and I can > not > find any data. > Bert > > > In a message dated 7/25/2013 2:48:43 P.M. Eastern Daylight Time, > ma...@non-stop.com.au writes: > > Hi Bert, > > I am sure your circuit is clear in your head, but would you mind attaching > detail? > You have perked my interest with the "low-noise" keyword ;) > > > -marki > > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of ewkeh...@aol.com > Sent: Thursday, 25 July 2013 11:39 PM > To: time-nuts@febo.com > Subject: [time-nuts] RS 232 > > Since joining time nuts over four years ago I have not used a single MAX > 232 chip. Two reasons MAX do not give me isolation and do generate noise > in critical applications. I prefer the use of two H11 opto couplers which > work perfect. On the receiving end the diode along with a current limiter > and blocking diode for the negative level works perfect. On the output > side > a power source is needed. If one uses an USB adapter it does have the + 5 > volt which again works perfect. How ever many prefer to use RS 232 > direct and that is why I hope to get some comments and suggestions from > the > list. Corby used on our counter circuit that he described a separate > power > source. > Present MAX circuits use a + 1.4 volt threshold but considering legacy > the question is what should the voltage swing be to make it compatible > for > most PC's and what options exist to get the necessary voltage. In the > past > other pins on the RS 232 port where an ideal power source. Still an > option? > Bert Kehren > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.