| ??? 08/21/07 18:32 Read: times |
#143461 - Could be, but I've never encountered it ... Responding to: ???'s previous message |
Kai Klaas said:
Richard said:
I don't recall EVER having an oscillator fail to start or have it fail in some other way. I know of some people having had problems with 8048 suffering from relaxation oscillations in the 10kHz range. I know of some self built radio remote controls also suffering from these nasty relaxation oscillations, especially those ones which had a socket for crystal changes. And I know from people having had problems with second hand US-army crystals, which suffered from too low Q and refused to start. Kai My 8048 types were mainly in the 2.5 to 6 MHz range, and, frankly, I never had any trouble with their oscillators starting. Now, the 8048 has negative-going RESET ... Perhaps they used that to kick-start the oscillator ... though I doubt it. Crystal sockets were more popular then than now, I know not why. They do add a bit of resistance (probably insignificant) and considerable capacitance (That might have been a contributor to the problem!) to the circuit. I've used 'em with no trouble, but that doesn't mean it's not risky. Military crystals were packaged to be compatible with the sockets that were common in military communication hardware. Those had larger pins than we see today, which handily plugged into sockets made to mate with them. The sockets were typically gold-plated, though the crystal cases and their contacts were not. The military crystals with which I've had what little experience I've had with them were in the 2.5 - 12 MHz range, mostly around 5.1 or so, |
