Homebrew PCBs

Rob,

It does, but the maximum operating temperature is 200�C for the 4148. 
With ~-2mV/�C tempco, it is difficult to build a controller that works 
well up to that temperature. You also need to calibrate it because the 
tempco is not constant over the full temperature range, nor is it 
exactly -2 mV/�C. I was unhappy with the way it worked when I did it, so 
I switched over to the RepRap thermistor. Unhappy with the poor 
performance at hot temperature, I bought the thermocouple based 
temperature controller.

The linearity of diode type temperature sensors is pretty good for short 
temperature ranges, but going from room temperature to the temperature 
ranges we are using didn't give me satisfactory performance.

For me, the thermocouple is the best route. Thermocouples are tricky 
because their terminations make additional thermocouples in series with 
the measurement couple, screwing up the readings. A packaged solution 
that takes care of the termination issues is the easiest way. At $8.99, 
a bargain! No fuss, no muss, no bother. And digital readout, too.

Harvey


On 1/1/2017 9:56 AM, Rob roomberg@... [Homebrew_PCBs] wrote:
>
> Always learning something new here.
> 1N4148 + LM741 makes a temperature sensor
>
>
>
> On 01/01/2017 07:11 AM, 'David C. Partridge' 
> david.partridge@... [Homebrew_PCBs] wrote:
>>
>> It\u2019s a Vivid IP-330 described as having \u201chot roller\u201d technology.
>>
>> I need to dig it out as I can\u2019t remember what I did to increase the 
>> Temp range (probably just changed a resistor in the op-amp circuit 
>> that used a 1N4148 as a Temp sensor).
>>
>> Can\u2019t find a parts list \u2026
>>
>> *From:*Homebrew_PCBs@yahoogroups.com 
>> [mailto:Homebrew_PCBs@yahoogroups.com]
>> *Sent:* 31 December 2016 18:11
>> *To:* Homebrew_PCBs@yahoogroups.com
>> *Subject:* Re: [Homebrew_PCBs] Re: Temp upgrades of lam's HOW high is 
>> high heat conditions
>>
>> Really? This grabs my attention.
>> What make and model?
>> Can you take a picture and share?
>> Is there an online parts list we can eyeball that shows how 
>> concentric heaters are mounted?
>>
>> On 12/31/2016 11:53 AM, 'David C. Partridge' 
>> david.partridge@... <mailto:david.partridge@...> 
>> [Homebrew_PCBs] wrote:
>>
>>     But, but the heaters are concentric with the rollers (or at least
>>     they are in my laminator) so
>>
>>     stopped/forward/reverse should make no difference.
>>
>>     Dave
>>
>
>