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mole42uk · 22nd Jul 2021, 7:21 pm

A quick update, I’ve had a month off due to medical intervention at the hospital, but I did move the project forward today by testing the “completed” hardware. The 1MHz and 10MHz square waves are good but I was disappointed to find that the 1MHz sine wave output was rather low level, until I remembered that the output emitter follower needs a 12v supply. So then I tested the power supply, nice steady 5v for the logic and GPS receiver but the 12v has a nasty 50Hz ripple of about 500mV, degrading the 1MHz sine performance somewhat. That’s the next job…..

22nd Jul 2021, 7:21 pm	#62
mole42uk Nonode Join Date: Aug 2010 Location: Resolven, Wales; and Bristol, England Posts: 2,614	Re: 1MHz output impedance query? A quick update, I’ve had a month off due to medical intervention at the hospital, but I did move the project forward today by testing the “completed” hardware. The 1MHz and 10MHz square waves are good but I was disappointed to find that the 1MHz sine wave output was rather low level, until I remembered that the output emitter follower needs a 12v supply. So then I tested the power supply, nice steady 5v for the logic and GPS receiver but the 12v has a nasty 50Hz ripple of about 500mV, degrading the 1MHz sine performance somewhat. That’s the next job….. __________________ Richard Index: recursive loop: see recursive loop