High temp thermometer.

Response time might be an issue. Smash the bulb.

Low wattage 120V bulbs are apparently mostly vacuum inside-- higher wattage ones have some inert gas.

Why not use a thermocouple? Or an RTD? That temperature is in the 'friendly' range.

What's wrong with a platinum resistance thermometer element?

-- Bill Sloman, Nijmegen

It has the thermal inertia of a 'hot plate', in which it will be in direct contact. Speakin' of "smashing bulbs" I designed an easy ultra low current igniter from one...

Regards Ken

Cost and performance. A bulb costs $.05 and is good to 2000F, using steel wire connects and glass is ok near 2000F,

Check $. Regards Ken

You can also make a Pirani vacuum gauge with one, if you can expose the filament to the chamber.

Choose your glass carefully. 2000F is 1093C, and soda glass melts around there

You can find cheaper examples, but if your time is worth anything, it's a lot cheaper to buy something calibrated than it is to try and improvise.

-- Bill Sloman, Nijmegen

if you're talking about an iron gauge, that requires a rather good vacuums before you energize the heater. I suppose one could make one.

Mr Edison discovered the thermionic effect, trying to do research on the soot build up on the heaters in lamps. His work led to many new ideas that got stolen by big business and other proclaimed inventors.

Jamie

You mean an _ion_ gauge (eg. Bayard-Alpert)? No, those are kind of a gassy triode.

A Pirani gauge measures the heat loss in keeping a filament at a fixed temperature, which is more-or-less linear with pressure over a range. Kind of like a hot-wire anemometer in still air.

Their useful range is mostly at higher pressures than the ion gauges (before you dare fire up the filament in the ion gauge).

Stolen _from_ Edison?

Best regards, Spehro Pefhany

Thermocouple?

Type J should do just fine and there are lots of cold junction compensated transducers available.

And the problem with a thermocouple is...?

They stink on ice. But never mind.

Cheers

Phil Hobbs

Yes, that is what I meant.

We also have a thermocouple vacuum probes in our system, too. It just heats an element and senses it, but the ion gauge is the final determination before HV is enabled.

Yes, that is correct. We have a separate control circuit just for that area, which handles both aspects.

Sure.. Read your history.

You read down a bit and see how the Edison effect gets a new label on it and then becomes some one else's property.

Nice world we live in. Bunch of cut throats.

Jamie

Lots of multimeters come with a thermocouple sensor, which should be good for that temperature range. 600F is a walk in the park for thermocouples.

My thought also.

Cheers

The OP needs one for around 500-600 F. That's the sweet spot for a J or K.

As Phil Hobbs says, even at a sweet spot, they are still thermocouples, and consequently unsuited to making accurate temperature measurements, not that Ken S. Tucker is going to be ambitious about accuracy.

-- Bill Sloman, Nijmegen

maanantai, 28. toukokuuta 2012 19.49.54 UTC+3 Ken S. Tucker kirjoitti:

Thermocouples are probably better but one thing with lamps. Today many bulbs or lamps are made of molybdenum. Because it is cheaper. So you should calibrate your sensor.

Yes, use a halogen bulb - they have a quartz envelope which will easily take that. A G4 capsule type isn't too big.

I used these as combined heaters/thermistors in a recent project where the duty cycle was such that they had plenty of time to reach ambient after the heating phase. Worked fine, but I found silver braze to be the most reliable way of connecting wires which were then insulated with fibreglass. In my case, the temperatures were lower than yours, so I don't know if silver braze or fibreglass would survive.

Copper braid is tempting as connecting wire, but be wary of the odd broken strand poking though the fibreglass sleeving, so use single core if you can.

Cheers