I bought several parts years ago planning to build my own 3d printer.
I'm just not getting back to the project.
I need help determining what kind of termistor i have for the hotend?
it's insulated 2 wires red cable.
I hooked up temperatore sketch i found from youtube. The sketch works but i dont think the the reading is correct. It jumps up and down even without the thermistor connected.
which sketch would be the right one for me to use?
And what is the resistance of your device at a known temperature? Change the temperature, either hot or cold and measure the resistance. What values do you get?
about 17-20 room temperator
heated with a lighter up to 200, there were delays tho
17-20 WHAT does that mean?
Maybe i misunderstood.
I hook up ohmeter to both end of the thermistor and the the number was around 19.
heat up the tip, it went up to 200.
did another measurement with 100ohmes in between and steady at 9. Heat it up with lighter, it went up to 25.
If that is a thermistor intended for temperature measurements, it is unusual, as it appears to be PTC (positive temperature coefficient). The resistance increases with temperature, and the resistance seems to be very low. Please post a close up, focused pic of the thing, showing any markings present.
To make temperature measurements, I suggest to get a NTC thermistor with 10K or 25K Ohm resistance at 25 Celsius. There are standard programs for Arduino that will give you reasonably accurate measurements with those, especially if you calibrate the sensor using this online calculator.
Yea there's no marking. I'm not even sure if my measurement is even correct. I guessed on the resistor.
Do you understand how to make a resistance measurement on your meter? The resistor in the photo above looks to me like 150 Ohms, so check that with your meter (and some other resistors, if you have them). If you don't have a collection of resistors, you can salvage some from discarded electronics.
you are correct, i measure the resistor alone and it's 150ohms. I have yet find a higher ohms resistor. Can't believe there aren't any 10k in old power supply.
The PCB on many discarded toys with internal electronics will have a collection of "old style" resistors with leads. Get them at thrift shops, garage sales, etc.
You can buy thermistors with known characteristics very cheaply on line. One random example
I have more electronic junk in the garage, i'll have to scout through. Too cold to be out during this midwest cold wave.
Also, i was wondering if i can use npn2222A transistor for thermistor? I used it for my HP heat sensor.
You can use the 2N2222 base-emitter junction as a diode temperature sensor. It obeys the diode equation, which is exponential with temperature.
The forward voltage drop changes by about 2 mV/degree Celsius, which you can read with an Arduino Uno R3, using the 1.1V analog voltage reference option.
https://www.pveducation.org/pvcdrom/pn-junctions/diode-equation
cool thanks. i'll try that. Do i still need the 10K R?
10K will work.
You get the best sensitivity and accuracy over a range of temperatures if you choose a resistor that has the same value as the thermistor, for a temperature in the middle of that range.
Omg I feel stupid. I don't think that was a sensor after I found a complete kit. The red wire must be the heater core and the tiny white cable is the thermistor.
The narrow red/black cable with the white JST connector is probably the heater power.
Surely some instructions came with that kit, so check 'em out!
no, the red/white is the fan. The actual sensor is all white. As i mentioned in the beginning, i bought this long time ago, no manual or pdf to go by.
Any recommended sketch i should play around with?
All i'm after is find what sensor it is so i can run the correct sketch and hook up the correct controller for a project with my kids with Bottle2PLA for his starter 3d printer.
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.
