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Voltage activated switch?
- Thread starter JohnnyAwesome
- Start date
Because it's been a while since I reviewed my own internal 555 schematic.
Your point is that when the Trigger input is held low, the Threshold input can override it. I agree for the original bipolar 555.
However ...
This is an undocumented condition, similar to having both the Set and Reset inputs to a S-R flipflop in the active states. Note that not all 555s are created equal, and some manufacturer's parts are configured such that it is the Trigger input that can override the Threshold input. The ambiguity about which input overrides which is is particularly true of the CMOS variants.
ak
Your point is that when the Trigger input is held low, the Threshold input can override it. I agree for the original bipolar 555.
However ...
This is an undocumented condition, similar to having both the Set and Reset inputs to a S-R flipflop in the active states. Note that not all 555s are created equal, and some manufacturer's parts are configured such that it is the Trigger input that can override the Threshold input. The ambiguity about which input overrides which is is particularly true of the CMOS variants.
ak
That's correct, I know what you are saying. That's why I specified a LM555 on the schematic
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