LOW FREQUENCY OSCILLATORS Circuit
If the capacitor is replaced with an electrolytic, the frequency of
oscillation will reduce. When the frequency is less than 1Hz, the
oscillator circuit is called a timer or "delay circuit." The 555
will produce delays as long as 30 minutes but with long delays, the
timing is not accurate.
555
Delay Times: |
C |
R1 = 100k
R2 = 100k |
R1 = 470k
R2 = 470k |
R1 = 1M
R2 = 1M |
10� |
2.2sec |
10sec |
22sec |
100� |
22sec |
100sec |
220sec |
470� |
100sec |
500sec |
1000secThe following circuits show a 1-5 minute timer and 10 minute timer:
|
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