Author Topic: Perfect Toast Every Time!  (Read 25193 times)

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Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #25 on: November 07, 2014, 01:32:23 am »
BTW, one thing I love about this old toaster is that when it ejects the bread, it really sends them flying out of the toaster to be then catched by a plate sitting nearby to its left. 

« Last Edit: November 07, 2014, 02:13:46 am by Beeper »
 

Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #26 on: November 07, 2014, 01:50:18 am »
I have another theory:  Once the surface of the bread starts to show some critical rapid rate of temperature rise, the optimal brown to perfection toasting time can be accurately approximated by the MCU to correctly then apply the coup-de-gras heat dose.
 

Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #27 on: November 07, 2014, 02:14:39 am »
Macbeth, when I was visiting London, staying at a B & B near the airport, everyday morning there was offered at breakfast fried bread! ( and pasteurized orange juice and greasy pork sausage!)

 bleurgh!
« Last Edit: November 07, 2014, 02:17:53 am by Beeper »
 

Offline Bored@Work

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Re: Perfect Toast Every Time!
« Reply #28 on: November 07, 2014, 06:57:52 am »
Me and my girlfriend have very different ideas on how to toast bread. She likes it light, I like it browned.

Cost of two new toasters - 120 Euro
Cost of a sharpie for marking knob positions on the toaster - 2 Euro
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Offline _Sin

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Re: Perfect Toast Every Time!
« Reply #29 on: November 07, 2014, 07:14:17 am »
Macbeth, when I was visiting London, staying at a B & B near the airport, everyday morning there was offered at breakfast fried bread! ( and pasteurized orange juice and greasy pork sausage!)

 bleurgh!

I can only apologise on behalf of my nation for your OJ experience. Sadly the British orange crop has been less than abundant in recent years, and importing whole oranges just for the juice is a bit wasteful...

Fried bread and greasy pork sausages on the other hand, are key components of the breakfast of champions (though for the real thing you might have to head North of London to the tune of 400 miles, where the fried starch component is supplemented with a tattie scone and the sausage flattened and de-skinned to more efficiently absorb the cooking fat).

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Offline mzzj

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Re: Perfect Toast Every Time!
« Reply #30 on: November 07, 2014, 07:47:19 am »
Just some idea. I am still brainstorming my project before committing to its implementation.

Firstly, the 555-timer circuit does a pretty good job, I only want or probably need to get a MCU to do a better job.

The key to toasting success with the original 555 design was to become a sophisticated toast maker. After a few slices of my favorite bread, I could correctly re-position the browning control to compensate for a heated toaster or compensate for the few different types of bread and bread temperatures I would encounter.

I just want a MCU to somehow get close to getting toasting right without me having to fiddle around with some bureaucratic toaster user interface having some fancy LCD screen or many pots to set moisture content, mass, initial temperature, etc.

What I will finally make must be simple to use.

But maybe I can accept adding a few momentary-contact buttons to give the toaster MCU some insight into the specific toasting task? A button for thick bread, cold bread, for instance? And tiny LED's to indicate these toasting customizations have been turned on for the current toasting session?

I just have to find some safe, clever way to make my toaster work better, I don't need perfect and neither me or my girlfriend will tolerate a complicated setup or toaster operation.

I have salvaged some infrared motion detectors from an automatic light that detects the presence of moving humans in it's vicinity. I wonder if I can somehow embed a single glass fiber optic to be positioned close to the surface of the toast and safely couple infrared light within this very thin heat-resistant thread of glass to some sensor on the PCB and get an idea of the heat radiated from the surface of the toast toasting to give me an idea of the toast surface temperature? The problem is that with these types of  infrared detectors, they want to detect moving objects, while a toasting slice sits still during the hot ride it is on.

Would an infrared sensor(such as above) detect the rate of change of temperature at the critical start of toast temperature?

I also know that I can purchase an infrared hand-held temperature meter that can accurately see the heat of a remote object, and I can cheaply buy this instrument this week on sale at a local store. In this way I can measure the surface temperature of the perfectly toasted toast at the instant of its final ejection. 

I can easily control the heating elements with a TRIAC and PWM to preheat the toaster(and the bread) to some standard temperature, thereby normalizing the starting temperature. The main consideration here is that this operation must not take too long. I would accept about a minute or so of first slice use  "calibration" by the toaster.

At the same time, I do not want to dry out the bread during  this calibration.

I have a theory:  Once the surface of the bread reaches some critical temperature, the optimal brown to perfection toasting time can be accurately approximated by the MCU to correctly then apply the coup-de-gras heat dose.
I think infrared temperature sensor and/or brownness detector are the best possibilities.  ;)
Something like this:
 https://www.sparkfun.com/products/9570
Or how about some electrical nose that will determine the correct toast degree based on smell?  ???
More measurements would be required.
 

Offline _Sin

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Re: Perfect Toast Every Time!
« Reply #31 on: November 07, 2014, 08:42:29 am »
I'm not convinced by those suggesting an optical approach to detecting 'brownness' in terms of getting the perfect toast - I think doing that right will be non-trivial.

Conceptually it's fine because I certainly know what the toast I want should *look* like, but I have trouble relating that to an arbitrary number on a dial, even on a toaster I'm familiar with.

Unless you're always toasting the same bread, and it's very uniform in appearance and you never stick the heel of the loaf in, then the results will be quite varied and thus the toaster will not be easy to use.

A white loaf generally toasts to a golden brown. A brown loaf toasts to a slightly darker brown. A loaf with fruit in will change unevenly. Marbled bread all bets are off.

If you *did* go down this route, and the above assumptions (and perhaps more - lighting conditions, especially under the glare of the changing heating element?) can't be assumed, then I think you'd need a good way to quickly specify *how* brown you want the toast, relative to how it starts. And that needs to be intuitive so you don't incinerate brown bread, etc.

My ideal interface would probably show an image of the untoasted slice on a screen, with a simulation of what it will look like after toasting. Set the dial until the image looks like what you want, and toast away.

Great, now I want to build a toaster. And also I want toast.

Mostly toast.
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Offline EEVblog

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Re: Perfect Toast Every Time!
« Reply #32 on: November 07, 2014, 08:48:52 am »
I was offered a job once at a small design house that had a patent on new toaster that used temperature controlled metal plates against the bread that ramped up and temp the toast a certain temp to ensure the most optimal result. And it could never burn.
Toasters were a running joke on another forum I was on at the time, so I didn't want to be known as a Toaster Designer!
 

Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #33 on: November 07, 2014, 12:23:04 pm »
mzzj has the right sensor, but how do I somehow protect it from the heating elements and yet position its point of view directly at the, say, near the middle of the toast's surface? 

I don't really know yet how to somehow keep this sensor far away from the toasting elements yet optically give it a clear view of a tiny spot on the center of the toast toasting. Whatever I do, it must be safe and yet robust in construction. I don't want any wires, PCB material or sensors burning to offer more flavor to the toast or encounter the sensor somehow getting entangled with mechanical moving toaster parts or especially with the inserted bread. I can't have it's field of view quickly fouled by crumbs from the toast. 

The sensor can only handle 85-deg C.

 I do have some #28 AWG silver coated solid copper Teflon wire-wrap wire, but I would only feel comfortable with this sensor mounted safely away from the heating elements, I want it sitting on the PCB.

Somehow this sensor must see through the material supporting the toaster's heating elements and not see the blazing heat of the heating element wires nearby.

The MLX90614 thermometer is small, very nice. It is factory calibrated in wide temperature ranges: -40 to 85°C for the ambient temperature and -70 to 382.2°C for the object temperature. The measured value is the average temperature of all objects in the Field Of View of the sensor. The MLX90614 offers a standard accuracy of 0.5°C around room temperatures.

Will a single tiny strand of glass fiber optical fiber do the job?
Will the optical fiber accept the very low freq. heat infrared when it is likely optimized for visible to UV light?
Will it only allow light input along its length and not from the sides facing the heating elements?
 How can I safely and securely mount  this optical coupling fiber to the heating element area?

I need some light weight, small diameter, non-toxic material that functions as a high temp resistant light tube, should I call NASA now to get to work on it as a favor to all those countless millions of people that love their proper toast in the morning?
« Last Edit: November 07, 2014, 01:43:00 pm by Beeper »
 

Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #34 on: November 07, 2014, 12:36:41 pm »
EEVBLOG, In my IMHO you would be admired by all geeks, engineers and toast lovers all over the world. No one has yet accomplished the engineering task of adapting the so easy to manufacture and cheap to make and use of a push-the-lever-down-two-slice-toaster design to consistently give the desired toasted result!

It is indeed a very challenging engineering problem worthy of the Nobel Prize.
« Last Edit: November 07, 2014, 12:50:48 pm by Beeper »
 

Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #35 on: November 07, 2014, 01:08:04 pm »
__Sin, thank you for your input, but you've got all the right arguments for the wrong sensor, it is temperature alone, I think, that  is the key. We should not  be trying to get a image to try to figure out the completion status of a varying toasting object.
« Last Edit: November 07, 2014, 01:23:09 pm by Beeper »
 

Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #36 on: November 07, 2014, 01:14:28 pm »
So, at this point all I know is that the key to toasting success with the original 555 design was to become a sophisticated toast maker. After burning a few slices of my favorite bread, I could correctly re-position the browning control to compensate for a heated toaster or compensate for the few different types of bread and bread temperatures I would encounter.

Alas, by the next morning, I usually have forgotten or confused all my expert "settings."

What's worse: If I make my toast at my girlfriends house and then forget to reset the Browness Control to her "very lightly toasted" desired setting, then I quickly find myself in the doghouse with her! It's something like not resetting the toilet seat cover, but somehow very more important.
« Last Edit: November 07, 2014, 01:24:56 pm by Beeper »
 

Offline _Sin

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Re: Perfect Toast Every Time!
« Reply #37 on: November 07, 2014, 01:20:08 pm »
__Sin, thank you for your input, but you've got all the right arguments for the wrong sensor, it is temperature alone, I think, that  is the key. We should not  be trying to get a image to try to figure out the completion status of the toasting object.

I'll be interested to see how you get on with that - I'm kind of sceptical that you can consistently decide when things are toasted to the same degree just from the temperature.  If the results are in any way reliant on the temperature profile of the heating cycle (including ambient effects such as room temp and even the bread temp) and/or the make-up or structure of the bread, then the temperature of the toast might not be a reliable indicator, nor entirely intuitive to alter depending on what you're toasting...

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Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #38 on: November 07, 2014, 01:28:04 pm »
_Sin, thanks again for your insight, you could be right and I failed to clarify my reason to chose temperature over imaging .

I am not considering temperature alone, but rate of change of temperature.

My theory(yet unproven) is that there exists a critical point, that it would be possible to detect a point in the toasting cycle where there is noticed a fast rate of change of temperature, and this time point would clearly give the MCU the correct feedback that toasting is very close to completion.
« Last Edit: November 07, 2014, 01:38:46 pm by Beeper »
 

Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #39 on: November 07, 2014, 02:04:40 pm »
 

Offline robrenz

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Re: Perfect Toast Every Time!
« Reply #40 on: November 07, 2014, 02:52:53 pm »
IMO the perfect toaster would have tiled array of 20mm square independent heater and optical pickup zones on each side of the bread. This would cure the uneven browning situation that inevitably occurs and all the other variables.

Offline Alex Eisenhut

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Re: Perfect Toast Every Time!
« Reply #41 on: November 07, 2014, 03:09:01 pm »
Macbeth, when I was visiting London, staying at a B & B near the airport, everyday morning there was offered at breakfast fried bread! ( and pasteurized orange juice and greasy pork sausage!)

 bleurgh!

I can only apologise on behalf of my nation for your OJ experience. Sadly the British orange crop has been less than abundant in recent years, and importing whole oranges just for the juice is a bit wasteful...

Fried bread and greasy pork sausages on the other hand, are key components of the breakfast of champions (though for the real thing you might have to head North of London to the tune of 400 miles, where the fried starch component is supplemented with a tattie scone and the sausage flattened and de-skinned to more efficiently absorb the cooking fat).

All OJ from a box is pasteurized, the companies hire perfume experts to put back some essential oils to make it taste better.
How else can you get OJ year round that always tastes exactly the same?
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Offline Macbeth

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Re: Perfect Toast Every Time!
« Reply #42 on: November 07, 2014, 03:42:57 pm »
IMO the perfect toaster would have tiled array of 20mm square independent heater and optical pickup zones on each side of the bread. This would cure the uneven browning situation that inevitably occurs and all the other variables.
This. Also you could fashion 8-bit pixel style images of Jesus and Virgin Mary on the toast and declare them a miracle and make your toaster a place of pilgrimage, fleecing the tourists for a slice. It could be more profitable than Lourdes.
 

Offline miguelvp

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Re: Perfect Toast Every Time!
« Reply #43 on: November 07, 2014, 03:45:39 pm »
IMO the perfect toaster would have tiled array of 20mm square independent heater and optical pickup zones on each side of the bread. This would cure the uneven browning situation that inevitably occurs and all the other variables.
This. Also you could fashion 8-bit pixel style images of Jesus and Virgin Mary on the toast and declare them a miracle and make your toaster a place of pilgrimage, fleecing the tourists for a slice. It could be more profitable than Lourdes.

Google "selfie toaster" we are getting one for our daughter for xmas, she is in college so the plan is for her to put it in the common area kitchen. :)
 

Offline robrenz

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Re: Perfect Toast Every Time!
« Reply #44 on: November 07, 2014, 03:47:10 pm »
IMO the perfect toaster would have tiled array of 20mm square independent heater and optical pickup zones on each side of the bread. This would cure the uneven browning situation that inevitably occurs and all the other variables.

This would also allow heat profiles ranging from toasted through where the bread is crispy throughout like melba toast to a crispy brown surface with a still soft core.

Offline mikerj

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Re: Perfect Toast Every Time!
« Reply #45 on: November 07, 2014, 04:11:21 pm »
216 seconds at 154 Celsius might be a good starting point.

A long time ago I remember seeing a news article about a toaster being developed which used a sensor to detect the caramelisation of the sugars produced by the Maillard reaction (the process that causes browning).  This was allegedly going to give absolutely perfect toast every time, but Google isn't showing me any currently available toasters that use this method,  However it did find this patent.
 

Offline miguelvp

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Re: Perfect Toast Every Time!
« Reply #46 on: November 07, 2014, 04:32:04 pm »
216 seconds at 154 Celsius might be a good starting point.

Pretty much they used a reflow oven :)

But again, don't use the same physical oven for both, I would even have an independent temperature sensor per toaster oven to avoid lead contamination.

 

Offline m100

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Re: Perfect Toast Every Time!
« Reply #47 on: November 07, 2014, 05:07:36 pm »
However it did find this patent.

Ionisation chamber ?  Radioactive Source?   aka a smoke detector   :-DD
 

Offline BeeperTopic starter

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« Last Edit: November 08, 2014, 02:44:39 am by Beeper »
 

Offline BeeperTopic starter

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Re: Perfect Toast Every Time!
« Reply #49 on: November 08, 2014, 12:58:26 am »
Scientists in Macbethland have figured it out, but they were using a toaster-oven. I am using a toaster!

==========================http://hub.jhu.edu/magazine/2013/spring/engineering-perfect-toast
....
Minsky concentrated on toast, which turns out to be tricky. Blame it on browning. "Browning is a positive feedback process that is actually exquisitely sensitive," he says. "As the toast becomes brown, or darker, it starts to absorb much more infrared radiation from the heating elements, thereby quickening the heating process, causing it to brown faster and faster." A few extra seconds or degrees of heat, he says, can make or break a piece of toast. The perfect amount of browning is essential, Cowan says, to achieve the Maillard reaction—the chemical reaction between an amino acid and a reducing sugar that in bread's case leaves a brown color.

Some researchers in the United Kingdom already had uncovered, or so they claimed, the recipe for perfect toast: heat at 154 degrees for 216 seconds. Using this as a base, Minsky and his team went to work tricking out an off-the-shelf toaster oven. They inserted a precision thermometer and connected it via relay to a controller that managed the heating process. The students then programmed the controller to maintain a constant temperature for the precise desired amount of time. The controller turned the heating element on and off if the interior conditions went above or below the specified temperature.

The results, Minsky says, were delicious. "It was shockingly good. We thought the first slice might have been a fluke, but we used two whole loaves of bread and every piece we made was light and golden brown, just the perfect amount of crispiness."
One small step for mankind.
==========================

They only used one type of bread!
What would the result be with switching from white to wheat to rye or muffin?

« Last Edit: November 08, 2014, 01:29:01 am by Beeper »
 


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