Logic gate using 555 timer(toggle switches and led circuit)
- Thread starter meepmorp
- Start date
Welcome to AAC!
Show what you've tried.
That works too, though does depend on whether 555 sinks or sources current in LED.
Yes, the LED would be need to be connected between V+ and the 555 output for that to work.
The resistor should be no more than about 600Ω to insure the 555 is in the Reset state.
Even if reset only requires 400uA?
Nevermind....could be as much as 1.5mA
This circuit add 50% duty cycle (regardless of change in frequency) if desired.
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The TS wants the LED continuously on when power is applied, so connect the LED to V+ instead of ground.
First pass at circuit for post #5. R1-C1 set the flash rate. To reduce parts and clutter, this circuit has a fixed 50/50 on/off ratio. C2 is power supply decoupling. It is a bit larger than normal because the 555 is switching the full LED current.
As above, R2 is less than 600 ohms for the bipolar 555. For the CMOS 555 in this schematic, it can be increased to almost anything. for example, it can be whatever value the R1 timing resistor is. With the CMOS 555, LED current must be limited to 50 mA max.
ak
As above, R2 is less than 600 ohms for the bipolar 555. For the CMOS 555 in this schematic, it can be increased to almost anything. for example, it can be whatever value the R1 timing resistor is. With the CMOS 555, LED current must be limited to 50 mA max.
ak
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Corrected in #11. Thanks.
If the LED is off its a don't care condition... Or so everyone has assumed, since there's not many obvious alternatives!
He could have meant that if one switch is on (either switch) then the LED is illuminated continuously but if both switches are on it flashes.
Already changed as of 12:25 pm per crutschow.
