Propane Flame Projector Controller

[4pyros]

Why do you need AC for flame conductivity testing?

John

You can not test for flame rectification without AC power.

 

[alec_t]

How about home-brew heating elements made from coiled nichrome wire (toaster/electric fire element), running off 24VAC?

 

[jpanhalt]

You can not test for flame rectification without AC power.

True, but you can test for flame conduction. Flames conduct in both directions, but better in one direction, which accounts for the DC offset/rectification that is often used. However, that use is often in a situation when AC is readily available. If AC is not available, then DC will conduct when there is a flame and not conduct when there isn't. Here is a patent using DC: https://www.google.com/patents/US2684115

John

 

[4pyros]

How about home-brew heating elements made from coiled nichrome wire (toaster/electric fire element), running off 24VAC?

Alac; I am thinking about it.
I would call it a Hot Wire Igniter.

 

[4pyros]

True, but you can test for flame conduction. Flames conduct in both directions, but better in one direction, which accounts for the DC offset/rectification that is often used. However, that use is often in a situation when AC is readily available. If AC is not available, then DC will conduct when there is a flame and not conduct when there isn't. Here is a patent using DC: https://www.google.com/patents/US2684115

John

Thanks John; I will look into that.

 

[4pyros]

Alac; I am thinking about it.
I would call it a Hot Wire Igniter.

Seems it has been done before but needs lots of power.
https://www.instructables.com/id/NiCrome-"hotwire"-ignition-for-propane-flame-effec/?ALLSTEPS

 

[4pyros]

Thanks John; I will look into that.

There is not much out there on electrical conduction of flames but I did find a flame detector kit;
https://www.thaikits.com/index.php/...-sensor-12vdcOnline Electronic Kit Store.html

Any idea how this works?

 

[alec_t]

Seems it has been done before but needs lots of power.

Yes, it will need lots of power. The gas blowing on the hot wire will cool it! I expect whatever you use will need a fair bit of power .

 

[alec_t]

Any idea how this works?

I would hazard a guess that the 'transformer' at bottom left plus a few adjacent components form an inverter putting out a high voltage (>1kV?) which is applied to the probes. Conduction between the probes when ions in a flame are present would then be detected by the rest of the circuit to energise the relay at bottom right.

 

[4pyros]

I would hazard a guess that the 'transformer' at bottom left plus a few adjacent components form an inverter putting out a high voltage (>1kV?) which is applied to the probes. Conduction between the probes when ions in a flame are present would then be detected by the rest of the circuit to energise the relay at bottom right.

I am not entirely sure high voltage is needed, I saw one schematic that ran off 12 volts but could not find much info on it.

 

[4pyros]

A Google of "uv flame detector" will bring up some of what I mentioned. However, the suckers aren't cheap

I finally found this and yes not cheep about $50!
**broken link removed**

 

[4pyros]

Put me in the IR group. Thinking about it a little more the UV I worked with were designed for a nice blue flame. Based on response I am also thinking a pilot light system, much like used on what are now older furnaces.

@ John, we had some of those radiant heaters you linked to around our loading docks. They work great! Serious warm heat during winters like this.

Ron

The IR sensors I have seen are about $100 for a sealed unit and around $20 for a hobby board that could melt.

 

[KeepItSimpleStupid]

4pyros: That's $45 for the sensor and $60 for the board.

 

[4pyros]

4pyros: That's $45 for the sensor and $60 for the board.

Cheaper here;
**broken link removed**

 

[large_ghostman]

Thats really cool! I vote IR as well, I use IR transistor detectors on my railway, if you put them down a small dark tube a little way then they are pretty immune to outside light and very directional