AlainB
Member
Hi,
This is my first post here. My knowledge in electronic is pretty small.
I used an HP Laserjet II fuser to transfer toner from paper to PCB copper plate. It is working very well. I made a driver for the motor and it is controlled by a Gcode file using TurboCNC 4,1 software.
I would have 2 questions and one wish about the circuit controlling the temperature of the lamp.
1- There is a little chatter when the relay switch on or off (like a buzzer). Not very much but still. I read somewhere that a capacitor would correct that but I cannot find back this article. I think they were talking about a 10Mf, 25 volts. Where should I put this capacitor? Or is there a better way to control this chatter?
2- The heating lamp is very powerfull. About 630 watts. It can destruct the whole fuser assembly in less than 10 seconds if not well controlled. I know it because I destructed one last week. Look at the picture. My question is how can I protect the relay. It get on for one second and off for 6 to 8 second approximately. I use a 20 amp. automotive relay. My other fuser has been destroyed because the contacts points of the relay fused together. This happened just after I installed a diode on the relay. I am wondering if it was a coincidence or if having the diode installed the wrong way could have weld the contacts points? Anyways!! ...So how could I protect this new relay? I mean not putting a diode but protecting it from the power of the lamp.
3- I wish I could monitor in real time the resistance of the thermistor. The DTDP swicth purpose is to isolate the thermistor and cut power to the relay while reading the thermistor value. A constant reading would be more interesting but it is not working if I plug the Ohms meter without isolating the thermistor. Would there be a way around that?
With this circuit, the cut in/cut out differential is about 1 to 1,4K. The working temperature is when the thermistor resistance read 6 to 6,5K.
Alain
This is my first post here. My knowledge in electronic is pretty small.
I used an HP Laserjet II fuser to transfer toner from paper to PCB copper plate. It is working very well. I made a driver for the motor and it is controlled by a Gcode file using TurboCNC 4,1 software.
I would have 2 questions and one wish about the circuit controlling the temperature of the lamp.
1- There is a little chatter when the relay switch on or off (like a buzzer). Not very much but still. I read somewhere that a capacitor would correct that but I cannot find back this article. I think they were talking about a 10Mf, 25 volts. Where should I put this capacitor? Or is there a better way to control this chatter?
2- The heating lamp is very powerfull. About 630 watts. It can destruct the whole fuser assembly in less than 10 seconds if not well controlled. I know it because I destructed one last week. Look at the picture. My question is how can I protect the relay. It get on for one second and off for 6 to 8 second approximately. I use a 20 amp. automotive relay. My other fuser has been destroyed because the contacts points of the relay fused together. This happened just after I installed a diode on the relay. I am wondering if it was a coincidence or if having the diode installed the wrong way could have weld the contacts points? Anyways!! ...So how could I protect this new relay? I mean not putting a diode but protecting it from the power of the lamp.
3- I wish I could monitor in real time the resistance of the thermistor. The DTDP swicth purpose is to isolate the thermistor and cut power to the relay while reading the thermistor value. A constant reading would be more interesting but it is not working if I plug the Ohms meter without isolating the thermistor. Would there be a way around that?
With this circuit, the cut in/cut out differential is about 1 to 1,4K. The working temperature is when the thermistor resistance read 6 to 6,5K.
Alain
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