Yours truly is no stranger to DIY sous vide setup, having dabble in
various microncontroller based home made sous vide setup. The PID controlled arduino sous vide setup by yours truly can be found here http://shin-ajaran.blogspot.sg/2012/12/coming-to-... This PID controlled arduino sous vide has been instrumental in setting up for the perfect dinner dates with the missus. I have cooked fabulous steaks, short ribs, lamb racks, and the epitome of my DIY sous vide home cooking: the effortless Beef Rendang. Details of the beef rendang can be found here http://shin-ajaran.blogspot.sg/2012/12/coming-to-...
After rubbing shoulders with humans at several maker faire, or maker inspired activities across the continents spanning many miles apart https://www.flickr.com/photos/uclengineering/1111...
humans often remarked: "it looks so complicated/dangerous/scary!", "I want to have one but I can't write the program/wire the electrical/solder the electronics", " i want to buy a commercial one/the parts/components, but it is out of my reach", etc.
After seeing a fellow foodie and sous vide enthusiast trying to justify to own a sous vide setup; considerations include the cost, the complexity of setting up, the safety. Perhaps there might be something I can help to bridge this money/time/technological gap. Note: sous vide campaigns on kickstarter is tempting, but the waiting time for delivery is causing him anxiety.
After some searching online for cheap alternatives, I came across this temperature controller from aliexpress that cost U$5.97 with free shipping (to Singapore, that is). It sports an 8bit 32pin MCU the STM8S103K http://www.st.com/web/catalog/mmc/FM141/SC1244/SS...
On the aliexpress product page, nothing was written about the control
theory used to ensure the settling time, the rise time w.r.t to the target temperature. This module also sports a relay that is capable of 10A to be used to control a heating apparatus. The other nice thing is, it fits in a regular name card holder. Nonetheless, the entry price is low enough to tempt me to click "BUY". There is a caveat, the manual that comes in the package is in chinese.
1. U$5.97 temperature controller module from "middle kingdom"
2. a modified single face plate AC socket & plug (UK standard socket and plug) repurposed from an extension
3. a heating vessel of choice. Reuse an existing crock pot, slow cooker, water heater and more.
1. digital thermometer
2. Fluke wireless thermometer is optional
this post also appears on my blog http://shin-ajaran.blogspot.sg/2014/09/cheapest-u5...
Step 1: Prep the U$5.97 Temperature Controller
prep the U$5.97 temperature controller. The exposed AC end that is very
close to the LHS push button has to be insulated. I have used some hot glue, and also a casing to isolate from human touching the PCB connectors accidentally. Thus module comes with screw terminals as connector for the DC supply and AC load. Solder a DC connector to the supply side. For the AC load side, I have used 2 jumper wires, one end is cript with a fork cable lug, the other end is tinned, and to be connected to a screw down terminal block. Jumper wires (in this case the blue and brown wires in the picture) are
needed to connect to the modified AC plug & socket. No colour scheme for jumper wire. I have used brown and blue from the recycle bins. If you want to be consistent with the colour of the live wire, use brown colour wire.
Step 2: Prep AC Socket & Plug
A modified AC socket & plug (UK standard socket and plug) is needed to used with the temperature controller module.
This step can be potentially hazardous if safety procedures are not observed. Do NOT work on an electrical AC socket while it is plug into a live source. Make sure the exposed leads are properly insulated. Wear proper foot wear that comes with rubber sole. Check the working environment has an ELCB tested to be functional. Do NOT use thin wires for AC load. Use the wire from a standard 3 core power cable.
Perform electrical wiring of a standard single face plate AC socket & plug as if it is going
to be used as an extension. Now, instead of the live wire (brown colour, UK standard) going directly to the socket pin where it is supposed to be; make an "open circuit" on the live wire and connect the exposed ends to the screw down terminal block. This terminal block will act as a "switch" to be controlled by the relay on the temperature controller module. Jumper wires (in this case the blue and brown wires in the picture) are needed to connect to the temperature controller module's AC load connector. No colour scheme for jumper wire. I have used brown and blue from the recycle bins. If you want to be consistent with the colour of the live wire, use brown colour wire.
Please note this might not be the best way of doing it with the wires exposed. If you have a better way of connecting a relay to an AC live wire, give me a shoutout.
prep a heating vessel. I have used a cheapo 1.3L mini heater jug cum
cooker as my heating vessel. It comes with an adjustable knob for the heat setting and is rated as 1100w (max) on the box. Any heating vessel that uses an AC wall outlet should suffice. But take note on the heating characteristic of the vessel.
connect all the components together. before turning it on, perform a
final check for correct wiring, proper insulation, AC safety standard, etc.
Step 4: Heating/temperature Test
perform intial heating/temperature test. make sure the temperature of the water bath is
registered by the sensor of the temperature controller module is approximately to the reading on the digital thermometer.
Step 5: Test Cook an 64degC 45min Egg
test cook an 64degC 45min egg.
Step 6: Observations
I have only cooked an egg at 64degC for 45mins. the cooked egg could be better. By observing the process of turning on and off of the relay by the controller, it appears to me this temperature controller module operates on a threshold basis. If temperature <= threshold by X, turn on the heater via the relay. else turn off the heater.
more observations need to be done to confirm whether it is running some sort of control theory or otherwise. The settling time taken to reach the ideal temperature and hold on it long enough for the cooking process do affect the outcome of food product cook en sous vide
I have cooked a chicken breast 65degC for 120min. The temperature has a wide fluctuation during the cooking period, especially when the relay is On/Off. the range of temperature observed was from 64.4 to -67.6 degC
Nonetheless, the supposedly 65degC 120min chicken still edible and the supposedly juicy and not dry texture