Oven Control
Jerry2
Posts: 3
Seasons Greetings.
Our gas kitchen oven gave up the ghost just in time to not cook the bird.
I've replaced the temperature sensor and glow plug to no success. Repair estimates to replace the controller are astronomical (and none can be found), so I have decided to replace the controller with a stamp and interface electronics. The original (and still current) problem is that the oven will only heat up to about 250 deg. F. I changed the temperature sensor and glow plug so I will keep them.
On the surface, it looks like a fairly straight forward project with the following elements:
- a temperature sensor interface
- a glow plug interface to ignite the gas
- a stamp running a PID control loop
- a gas flow valve interface
- an ignition detection sensor (?)
- interface electronics
With the exception of the controller, I'm planning on keeping all of the existing elements in the oven (sensors, control valve and glow plug) and just replace the control electronics.
I have a few questions about the sensors and was hoping for some help here.
Oven Temperature Sensor: How do these things work? Does it appear as a temperature variable resistance? Should I build a voltage divider around it and interface it to an analog to digital circuit?
Ignition Detection Sensor: I'm assuming there is some kind of safety sensor in there that detects when the gas is ignited. Does anybody know how these work?
Glow Plug: I'm assuming this is a simple resistive element that heats up to ignite the gas. I'm also asuming that there is a relay of some sort that switches this to household AC power. Does this sound right?
Gas Flow Valve: Again, I'm assuming, but I think this is a simple solenoid on/off valve under PID control. Or, do you think it has some variable flow rate capability and if so, how does one control the rate? If it is a simple on/off valve then there would be a lot of glow plug switching to reignite the gas when more heat is called for.
PID Control Loop: This is actually the least of my worries as there are many well documented examples of implementing one, but any advice would be welcome.
Interface Electronics: If my above assumptions are correct then some AC relays with suitable drive transistors should do the trick but again, any advice is welcome.
Regards,
Birdless at Christmas
Our gas kitchen oven gave up the ghost just in time to not cook the bird.
I've replaced the temperature sensor and glow plug to no success. Repair estimates to replace the controller are astronomical (and none can be found), so I have decided to replace the controller with a stamp and interface electronics. The original (and still current) problem is that the oven will only heat up to about 250 deg. F. I changed the temperature sensor and glow plug so I will keep them.
On the surface, it looks like a fairly straight forward project with the following elements:
- a temperature sensor interface
- a glow plug interface to ignite the gas
- a stamp running a PID control loop
- a gas flow valve interface
- an ignition detection sensor (?)
- interface electronics
With the exception of the controller, I'm planning on keeping all of the existing elements in the oven (sensors, control valve and glow plug) and just replace the control electronics.
I have a few questions about the sensors and was hoping for some help here.
Oven Temperature Sensor: How do these things work? Does it appear as a temperature variable resistance? Should I build a voltage divider around it and interface it to an analog to digital circuit?
Ignition Detection Sensor: I'm assuming there is some kind of safety sensor in there that detects when the gas is ignited. Does anybody know how these work?
Glow Plug: I'm assuming this is a simple resistive element that heats up to ignite the gas. I'm also asuming that there is a relay of some sort that switches this to household AC power. Does this sound right?
Gas Flow Valve: Again, I'm assuming, but I think this is a simple solenoid on/off valve under PID control. Or, do you think it has some variable flow rate capability and if so, how does one control the rate? If it is a simple on/off valve then there would be a lot of glow plug switching to reignite the gas when more heat is called for.
PID Control Loop: This is actually the least of my worries as there are many well documented examples of implementing one, but any advice would be welcome.
Interface Electronics: If my above assumptions are correct then some AC relays with suitable drive transistors should do the trick but again, any advice is welcome.
Regards,
Birdless at Christmas
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