Temperature sensor

[pete123]

I've ordered exactly the same temperature probes & display as Jonnycj mentioned at the bottom of this link.

ukwoodfiredovenforum.proboards.com/index.cgi?board=bvovens&action=display&thread=242&page=4

Thanks for the advice Jonny.

I've ordered the transformer as well. If I can't face the electrical work I could put a 12V battery inside the wood store.

I may have bought the wrong display? I think these are the correct ones. --- This one is 24V?? I'll post again if I ever work it out.

www.ebay.co.uk/itm/Digital-DC-Temperature-Meter-K-Type-Thermocouple-C-/250559826626?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a56878ac2#ht_2190wt_888

I bought the ones which end "EGT" by mistake. Take care they are very similar.

OK ignore some of the above. The original thermocouple & display work perfectly it was the transformer that was wrong - It must be a DC one & the link above is for a halogen light and won't work - see below post for the correct one - modified 25/6/12

[dougclay]

Those thermocouples are the same as I got, they are a lot bigger than the picture on ebay would make you think... the probe is about 1cm in diameter so not really one to squeeze between your floor bricks...
The cable is very long though, so I have cut one of them into smaller cables. Thermocuples are all about the join between the two types of metal so as long as you have a good tight twist at the end, you have a thermocouple, a weld of some kind would be better, but for experimental purposes... :-)

[pete123]

How far do you set them into the bricks? Can they be flush? Or do you leave them sticking out into the oven by 10 - 20mm?

[dougclay]

The 2 different metal wires will be welded to the inside of the end of the probe, so if you are talking about the large ones from hk... I would make it flush... the end face is probably as sensitive to temp as the outer edge... test is with a lighter and see which part of the probe causes the biggest jump in temp... it should be the very end..

[pete123]

Thanks - Very helpful. I'll try that when they arrive.

[faz]

Personally, I wouldn't have the thermocouple directly exposed to the oven interior, as it may suffer from corrosion. Bedding it into a brick or the mortar say 10mm behind the face would seem better to me. It should still respond fairly quickly to temperature changes within the oven and there shouldn't be too much lag.

[turkey]

if they are that fat what about drilling a hole into a firebrick and fill the hole with very wet homebrew to get a good solid fill. Then you should get the reading of the oven fabric?

[pete123]

Thanks the're not here yet I'll play around with them when they arrive,

[pete123]

This is a mainly duplicate entry from my own build post:-

I've worked out my thermocouple issues now.

I was using the wrong transformer. It was a 12 V A/C one and I needed a DC model.

for £1.99 I've discovered these.

www.ebay.co.uk/itm/Philips-Mains-....61#ht_512wt_888

I give in - the e-bay link didn't work - try typing in "Philips Mains Adapter 12v 50mA Output DC Plug" into google - its some sort of digibox power supply.

I've cut the end off & it works a treat. I'm not sure exactly how to keep them waterproof though.

I thought I would cheat & only bought one transformer and ran a wire in parallel from one to the other. I should have paid more attention in physics class because that doesn't work. You need one transformer (ie. plug) per display. At the price it won't break the bank.

24degrees C. isn't far off & when I waved my weed burner inside the oven it was straight up to 90 or so.

Success.

So in a nutshell both the original thermocouples and the displays work perfectly. It was the transformer I bought that was wrong. The displays are a bit fussy but having got the correct transformer - happy days.

Read more: ukwoodfiredovenforum.proboards.com/index.cgi?board=pompeiiovens&action=display&thread=296&page=15#ixzz1ypcRDmXn

Attachments: