I'll have a LVDS signal with data or a square wave, in the range of maybe 1 MHz to 2 GHz. I figure I can pump it through an 10EP89 ECL buffer to give it some heft. Each output will become almost 2 volts p-p.
I'd like to light an LED if there is signal present. How does this look?
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The 10 pF caps shouldn't load my signals much, especially in the lower signal path that doesn't need to be super fast.
I suppose I could buy some fancy RF detector chip, but I'd rather just use fairly ordinary parts.
Any other ideas?
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John Larkin Highland Technology, Inc
lunatic fringe electronics
I suppose I could clock a 1 into an ECL flipflop, and clear the flop at, say, 1 KHz. The flop would drive the LED. That's a more 'official' design, a bit more expensive maybe.
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John Larkin Highland Technology, Inc
lunatic fringe electronics
What I've done (not knowing the duty cycle of a signal pulse) is toggle a flipflop. On anything regular, that makes a 50% duty cycle square wave.
Flipflops have true/invert outputs, so a capacitor-resistor limiter into a back-to-back LED pair makes indicator that only lights up when there's logic transitions.
This one was battery-powered, sensing a TTL pulse.
Oh, you can also simplify it if you don't mind it missing a single transition one way only. Signal thru C, R to ground, through R into tr. Add collector led/r. Job done.
I thought the symmetry was pleasing, with equal loading on each logic line. I guess I have lots of signal, by RF standards, so one zero-bias detector should work fine.
Even one diode should work.
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John Larkin Highland Technology, Inc
lunatic fringe electronics
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