Hi everybody, I have come up with my own circuit for a repeat cycle timer that switches a motor ON for 1 minute and OFF for 4 minutes and repeats this forever.
The NAND gate oscillator generates a 1 Hertz clock pulse which is fed to both the counters.
The first counter counts till 60 pulses (i.e. 60 seconds = 1 minute) and then directs the clock pulses to the second counter. The second counter counts till 240 pulses (i.e. 240 seconds = 4 minutes) and resets both the counters. This causes the first counter to start counting again.
The relay is activated using the first counter using a relay driver transistor 2N5089TF (with hFE 400). I read on the internet to use a transistor that provides at least 5 times the required current gain (375). The relay draws 75mA and since the NAND gate supplies about 1mA so the required current gain is 5 X (75/1) = 375.
The circuit will be powered by a 12v sealed lead acid battery to run a 12v water pump.
I am looking for any comments / suggestions from the experts to improve this circuit. Thank you in advance for your valuable time and inputs.
The NAND gate oscillator generates a 1 Hertz clock pulse which is fed to both the counters.
The first counter counts till 60 pulses (i.e. 60 seconds = 1 minute) and then directs the clock pulses to the second counter. The second counter counts till 240 pulses (i.e. 240 seconds = 4 minutes) and resets both the counters. This causes the first counter to start counting again.
The relay is activated using the first counter using a relay driver transistor 2N5089TF (with hFE 400). I read on the internet to use a transistor that provides at least 5 times the required current gain (375). The relay draws 75mA and since the NAND gate supplies about 1mA so the required current gain is 5 X (75/1) = 375.
The circuit will be powered by a 12v sealed lead acid battery to run a 12v water pump.
I am looking for any comments / suggestions from the experts to improve this circuit. Thank you in advance for your valuable time and inputs.
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