Hi All:
I have a fountain at our church that was built from scratch by an artist and I need some control circuitry. One of our members started on the project but his health has deteriorated and he cannot find his schematics. I have some experience with electronics. I used to build TTL logic circuits with gate chips, flip-flops, etc. when Radio Shack still had tube testers. Nothing since, thus I am very rusty. So-
Requirements
Sense the water level to stop the fountain pump if the water level is too low.
Automatically control a 24vac irrigation valve to fill the reservoir.
I thought about mechanical at first but here are the issues.
1) Fountain is set in concrete pad [part of the design]. Reservoir is under fountain, below grade and not visible.
2) Fill/drain plumbing is already in and is under the concrete & fountain. The irrigation valve is also in place on the edge of the pad - about 9ft [2.75m] away.
3) Access to reservoir and pump maintenance/removal is under several inches of stone. It is a cylinder about 8in [20cm] dia. x 10in [25cm] deep. Clearance is about 1 to 2 in [2.54 to 5cm] total on the sides when removing pump.
Could you please eyeball the attached? As I stated, I am very rusty on my circuit design - especially non-ttl. I got the idea to use a Schmitt NAND gate from a plant soil moisture indicator [preventing dc electrolysis of probes]. So I 'hijacked' the concept and expanded with some digital logic concepts. You will see that I am using U1B as an oscillator to generate an ac signal for all of the probes. My main concern is if I am using the correct logic - positive vs negative.
Also - I would like to include LEDs to indicate which probe is above water level. I can borrow ideas from other schematics with npn transistors driving the relay coil but I have forgotten how with pnp transistors.
Any and all opinions will be welcome.
Thanks in advance for any help.
Bob
I have a fountain at our church that was built from scratch by an artist and I need some control circuitry. One of our members started on the project but his health has deteriorated and he cannot find his schematics. I have some experience with electronics. I used to build TTL logic circuits with gate chips, flip-flops, etc. when Radio Shack still had tube testers. Nothing since, thus I am very rusty. So-
Requirements
Sense the water level to stop the fountain pump if the water level is too low.
Automatically control a 24vac irrigation valve to fill the reservoir.
I thought about mechanical at first but here are the issues.
1) Fountain is set in concrete pad [part of the design]. Reservoir is under fountain, below grade and not visible.
2) Fill/drain plumbing is already in and is under the concrete & fountain. The irrigation valve is also in place on the edge of the pad - about 9ft [2.75m] away.
3) Access to reservoir and pump maintenance/removal is under several inches of stone. It is a cylinder about 8in [20cm] dia. x 10in [25cm] deep. Clearance is about 1 to 2 in [2.54 to 5cm] total on the sides when removing pump.
Could you please eyeball the attached? As I stated, I am very rusty on my circuit design - especially non-ttl. I got the idea to use a Schmitt NAND gate from a plant soil moisture indicator [preventing dc electrolysis of probes]. So I 'hijacked' the concept and expanded with some digital logic concepts. You will see that I am using U1B as an oscillator to generate an ac signal for all of the probes. My main concern is if I am using the correct logic - positive vs negative.
Also - I would like to include LEDs to indicate which probe is above water level. I can borrow ideas from other schematics with npn transistors driving the relay coil but I have forgotten how with pnp transistors.
Any and all opinions will be welcome.
Thanks in advance for any help.
Bob
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