 CD74HC14E's problem with output
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Tonic
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Sun Jul 06 2008, 11:48AM
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Registered Member #528
Joined: Fri Feb 16 2007, 10:32PM
Location: Warsaw, Poland
Posts: 166
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Now I'm working on primary feedback circuit and obviously I can't get it working. The signal (in my case, NE555's output) is catched by this 1:200 ratio current sense transformer:
The rest of feedback circuit is done exactly as in Steve Ward's DRSSTC scheme  (1N4148/1N5819 combo -> 1kohm resistor -> DC blocking capacitor -> 1N4148 clamping diodes -> 74HC14)
The 74HC14 (exactly it's CD74HC14E) is powered by +5V + decoupling capacitor. I've checked with another samples in case of destroyed chip.
Waveforms:
The top is NE555's output, bottom 74HC14's input, set at 5mV/div (0.2mV peak-to-peak)
Now see, how 74HC14's output looks:
Now one thing wonders me, 0.2mV p-p seems to be pretty low value.. the NE555's output has 13V p-p, wouldn't the 74HC14's input signal voltage be higher?
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