Reddit reviews Signstek 3 1/2 6802 II Dual Channel Digital Thermometer -58°F~1022°F(-50~1300°C) with 2 K-Type Thermocouple Sensor Probe

Or you can just take a rheostat or dimmer switch or whatever and and mount it in a wallbox inline with the AC and badabing badaboom your twenty dollar weller just got a whole lot fancier. The just use a thermocouple and sharpy to mark various temps around the dial.

Have you seen what Amazon has on sale today?

http://www.amazon.com/Signstek-Channel-Digital-Thermometer-Thermocouple/dp/B00FFYEPVQ/

Also, for the price, this thermocouple can't be beat:
https://www.amazon.com/gp/product/B00FFYEPVQ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I'm on my 4th or 5th roast with the same setup and it's worked out well so far. I haven't had much to tweak, just:

• Replaced the plastic stirrer rod cap with a regular hex nut and some washers.
  
• Made a riser ring, 2" tall, from some aluminum sheet metal
  
• Disconnected the popper's heating element because it plus the oven was trying to draw over 20 amps. The element would cut out after a minute or two (heat limiter most likely) but I don't want to pop any breakers, and all the real heating comes from the oven not the popper.
  
  I haven't had to touch the stirrer rod yet. Monitoring the temperature of the beans is done with a digital thermometer, I simply shove the probe down into the beans. Feel free to hit me up with any other questions.

When I got my new source XL gr1 inset it to 366 and it defiantly improved. If you want to test it get one of these Signstek 3 1/2 6802 II Dual Channel Digital Thermometer 1300°C 2372°F with 2 K-Type Thermocouple Sensor Probe https://www.amazon.com/dp/B00FFYEPVQ/ref=cm_sw_r_cp_awd_xHQLwb0FWK2S2

Throw a themocouple in your oven next time you clean it. You can be within a few %, which is more accurate than your oven's built in thermometer is anyway.

If you don't have one or a multimeter, you can buy a themometer with 2 probes for $20: http://smile.amazon.com/Signstek-6802-Channel-Thermometer-Thermocouple/dp/B00FFYEPVQ/ref=pd_sim_hi_21?ie=UTF8&refRID=03ER12NYTAT2H33ZTVAH

Drill a hole for a probe and use something like this https://amzn.com/B00FFYEPVQ

A cheap thermocouple will go a long ways with this (and future diagnostics). I got one from amazing for about 20$.

http://www.amazon.com/gp/product/B00FFYEPVQ/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

Alternatively - you could just replace the resistor with a 4.7k pull up - which would cost all of 50cents.

Do you need that many channels? I would go with something simple [this] (http://www.omega.com/pptst/OM-EL-USB-TC.html) if you don't need to centralize a bunch of inputs.

If you don't need USB (logging/monitoring) you could use something like this instead.

If you can afford it (say $70) - don't get a Thermapen, get a K Type thermocouple brain and a food-grade submersible probe.

The brains are universal and cheap (and read up to two probes independently)

https://www.amazon.com/Signstek-Channel-Digital-Thermometer-Thermocouple/dp/B00FFYEPVQ/ref=sr_1_9?ie=UTF8&qid=1483083745&sr=8-9&keywords=K+type

The probe looks like this:

https://www.amazon.com/Cooper-Atkins-50360-K-Thermocouple-Stainless-Temperature/dp/B00DYC9ZUW/ref=sr_1_1?ie=UTF8&qid=1483083631&sr=8-1&keywords=K+type+thermocouple+food

Apart from these two pieces, you need a 9V battery. Some 3M foam tape is also good if your dad does Sous Vide. These thermocouples allow for constant probe readings the way you'd use an old fashioned roasting probe, except you can use this under water, in oil, in a smoker, on a grill, in a fridge, or in a pan. For things that overcook quickly or are blind cooked, this is the best thermal tool you can get right now.