Hello.
I want to build a simple circuit that would control a humidifier in a terrarium.
I have 39 ohm 10 Watt resistors.
I have two kinds of PTC thermistors: "10P" and "16P" — I don't know their characteristics curve.
I was not able to find a good datasheet with the graph for "10P" and "16P" thermistors.
The big one, the "16P" can control a 12 volt, 40 ohm light bulb that is wired in series.
At 20 degrees C, the wet thermistor conducts enough current for a light bulb to burn bright, after two minutes, the thermistor gets hot and the light goes out.
I also have 5.1V, 5 watt 1n5338B zener diodes, 20pcs.
To control the load, I bought a 5-60 VDC Solid State Relay with a 3-32 VDC input.
Ideally, I would like this circuit to be sharp enough to use regular relays without causing contacts to buzz, as the voltage nears the low threshold.
Can zener diodes be used to solve this problem?
How did they solve this problem in the analog days?
What circuit should I use to control the humidifier load,
so when the water starts precipitating down and accumulating in the lowest spot in the system,
the humidifier circuit would be opened by the relay?
If I were to design a circuit as in this picture:
How do I calculate the values of R1 and R2 to get the sharpest corners on the graph on the oscilloscope?
The half-wave AC generator symbolizes the changing resistance of the thermistor.
Can I combine the thermistor with R1 or R2?
Thank you.
I want to build a simple circuit that would control a humidifier in a terrarium.
I have 39 ohm 10 Watt resistors.
I have two kinds of PTC thermistors: "10P" and "16P" — I don't know their characteristics curve.
I was not able to find a good datasheet with the graph for "10P" and "16P" thermistors.
The big one, the "16P" can control a 12 volt, 40 ohm light bulb that is wired in series.
At 20 degrees C, the wet thermistor conducts enough current for a light bulb to burn bright, after two minutes, the thermistor gets hot and the light goes out.
I also have 5.1V, 5 watt 1n5338B zener diodes, 20pcs.
To control the load, I bought a 5-60 VDC Solid State Relay with a 3-32 VDC input.
Ideally, I would like this circuit to be sharp enough to use regular relays without causing contacts to buzz, as the voltage nears the low threshold.
Can zener diodes be used to solve this problem?
How did they solve this problem in the analog days?
What circuit should I use to control the humidifier load,
so when the water starts precipitating down and accumulating in the lowest spot in the system,
the humidifier circuit would be opened by the relay?
If I were to design a circuit as in this picture:
How do I calculate the values of R1 and R2 to get the sharpest corners on the graph on the oscilloscope?
The half-wave AC generator symbolizes the changing resistance of the thermistor.
Can I combine the thermistor with R1 or R2?
Thank you.