Hi folks This looks like a great forum! I've been reading some background material and trying to see if the answer to my question is in the forum, but I haven't found anything. Let me say briefly that I "used to be" a chemical engineer, so I have some technical background, but it was CHEMICAL. I'm pretty lost when it comes to electronics. I understand basic generation a/c and d/c, circuits in school 30 years ago, etc. What I know about circuit boards would fill 1/2 a paragraph, lol.
I am trying to design what I think is a simple device to sound an audible alarm when boiling water in a pot reaches a low level. I wanted to achieve this without a mechanical float, and I found a circuit that seems to fit the bill, sort of. Below is a copy of the circuit, but the designer at circuitsgallery.com doesn't seem interested in helping people figure out why it doesn't often work. The principle, as I understand it, is that a probe is inserted into the water do the desired depth. This provides a ground and keeps a transistor closed (learned about how transistors work last night, lol). When the water drops below that level, the voltage in the line opens the transistor and causes the alarm.
I have a number questions, but I'd like to ask just a couple to get started (don't want to scare anybody off with 1000 questions about something so simple).
1. Would you consider this generally a good design, and one that could be modified to work for my specific situation. For instance, if I want to use an 18" long stainless rod as the probe, I imagine I might have to change some of the components in the circuit in order to make it work.
2. Can this be made to work using a battery rather than a/c power supply? I would like to make it portable and to use as little battery power as possible.
Hopefully I've described things adequately. Any help, or direction if this is the wrong forum would be greatly appreciated!
Dan
I am trying to design what I think is a simple device to sound an audible alarm when boiling water in a pot reaches a low level. I wanted to achieve this without a mechanical float, and I found a circuit that seems to fit the bill, sort of. Below is a copy of the circuit, but the designer at circuitsgallery.com doesn't seem interested in helping people figure out why it doesn't often work. The principle, as I understand it, is that a probe is inserted into the water do the desired depth. This provides a ground and keeps a transistor closed (learned about how transistors work last night, lol). When the water drops below that level, the voltage in the line opens the transistor and causes the alarm.
I have a number questions, but I'd like to ask just a couple to get started (don't want to scare anybody off with 1000 questions about something so simple).
1. Would you consider this generally a good design, and one that could be modified to work for my specific situation. For instance, if I want to use an 18" long stainless rod as the probe, I imagine I might have to change some of the components in the circuit in order to make it work.
2. Can this be made to work using a battery rather than a/c power supply? I would like to make it portable and to use as little battery power as possible.
Hopefully I've described things adequately. Any help, or direction if this is the wrong forum would be greatly appreciated!
Dan
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