On Mon, February 26, 2018 2:29 pm, Tom Van Baak wrote: > BTW, a trick for blinking LED's -- use two of them out of phase: one that > the user sees on the front panel and one that is blacked out or hidden > inside. A flip-flop (Q and /Q) or even a set of inverters is all you need. > The current draw thus remains constant in spite of the blinking. You could also use a long-tail diff-pair, with the LED in the collector circuit of just one side of the pair. Only costs one extra transistor and a few resistors and then the current draw is (close to) constant whether the LED is on or off. -- Chris Caudle

Hi, On 02/26/2018 08:42 PM, Gerhard Hoffmann wrote: > Am 26.02.2018 um 20:20 schrieb Tom Van Baak: >> Fun fact -- there's a wide spur at ~2 Hz on the 5065A phase noise >> plot. What do you think that is? On a hunch I opened the front panel >> and reset the blinking amber battery alarm lamp, and voila, that noise >> went away. Makes sense when you think of the power variations >> associated with a blinking incandescent lamp. > > There was a Tektronix sampler that had a few ps sampling jitter to the tune > of a blinking LED on the mainframe  :-) I was just about to comment on that. The Tek 11803 / CSA803C TDR module has a blinking LED with "HOT" TDR pulse. It however skews the timing so a later firmware disabled the blinking. Sadly to say, I don't have that FW on mine CSAs Cheers, Magnus