[email protected] said: >> Alternatively, is there a simpler way to achieve the goal? > No, you really need a level shifting stage that > converts the PPS to RS232 levels.
I've been running a PPS from a TBolt directly in to a RS232 without a level shifter for years without any problems. In the old old days, the 1488 and 1489 were the TTL to RS232 level shifter chips. (I forget which was transmit and which was receive.) The receive side had an input threshold of roughly 1.4 V, same as TTL logic. All the followup replacement chips kept that property. Too many people depend on things like this working. On a lab bench, I'd expect things to work fine without a level shifter. It won't work as well with long cable runs or crappy grounds. If I was doing something like you want to do, I would do something close to what Brent Gordon described. I might add a 50 ohm resistor. Part of me tries hard to be nice to lab gear like coax cables. The idea of deliberately cutting a cable in two just isn't part of my culture. But it's a great way to get some coax already connected to a connector and it doesn't cost much. (actually you get two of them) That approach is often used for high speed scope connections. Solder one end of a 1K resistor to the point you want to look at. Attach center of coax to the other end. Find a nearby ground. Set the scope to 50 ohm input. That gives you a 20:1 divider. (actually, 21:1, use 950R if you want better accuracy) Most TTL/CMOS drivers are happy with a 1K load. -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
