Mini Temperature Sensor

[nztdm]

I had an idea that a mini temperature sensor would be very useful for inside laser hosts. Its just an idea at the moment but I have some parts on the way.

Basically, it will consist of:
SMD PICAXE 08M/08M2 Microcontroller
DS18B20 Digital temperature sensor on thin leads (TO-92 package)
4.7k SMD Resistor (needed for temp sensor)
78L05 SMD Voltage Regulator
Mini piezo buzzer

OR to save a little space, I could use a thermistor on leads (i have some tiny thermistors)
This will need a 10k SMD resistor instead of 4.7k
10k SMD trimpot for calibration

Basically it will come to about $8.50

The largest part is the buzzer. It's about 1cm diameter and 0.7cm high.
I know tiny SMD piezo buzzers exist but I cannot source them in small amounts. (Plz let me know where I can find some)

For single cell builds, I can just forego the voltage regulator as the PICAXE runs fine off of 3-5V.
However, with these varying voltages, thermistor readings could vary which causes all the more reason to use the DS18B20 digital sensor. If you can fit a TO-92, you should use the digital sensor.

My plan is, to make it constantly beep at an agreed upon temperature for when I program the chip.

Also I have not done SMD soldering before but I learn quick. :thinking:

Tell me if you think anyone would be interested.

 

[lasersbee]

1) the thermistor will be MUCH smaller than the TO-92 device.
2) an LED will be MUCH smaller than a buzzer.
3) normal sized hosts already take up most of the free space
in a host so the circuit MUST be made Ultra Small.
4) a good idea just the same....:beer:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

 

[Cyparagon]

Or just use a thermal switch that cuts power to the driver for $1.50

 

[Multimode]

Or just use a thermal switch that cuts power to the driver for $1.50

Thats just boring.

With a micro controller, you could have a slow flash for 'approaching temp' limit, solid for 'at limit' and then if temp continues to rise an auto power off.


ATB
MM

 

[Cyparagon]

Why stop there? Add in voice recognition, finger print security, and solitaire while you're at it.

 

[Multimode]

Why stop there? Add in voice recognition, finger print security, and solitaire while you're at it.

I can't understand how this would help in protecting for overtemperature
....a built in game would be good though :beer: Solitaire is a bit boring, Monopoly would be much better

 

[lasersbee]

Why stop there? Add in voice recognition, finger print security, and solitaire while you're at it.

Yeah.... why use a current regulated driver... Just use a resistor...:crackup::crackup::beer:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

 

[DrSid]

Why use resistor ? Select proper battery and go direct !

 

[lasersbee]

^^^ There you go....
@ nztdm...

never let naysayers interrupt your train of thought...
If you think it is a good idea... I say go for it..:beer:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

 

[Cyparagon]

I can't understand how this would help in protecting for overtemperature

voice recognition and finger print verification to over-ride the shutoff, and solitaire to play while you wait for it to cool.

LEDs are boring.

 

[nztdm]

Thats just boring.

With a micro controller, you could have a slow flash for 'approaching temp' limit, solid for 'at limit' and then if temp continues to rise an auto power off.

That sounds like a good idea. I could even make it a bi-colour LED.

Yeah.... why use a current regulated driver... Just use a resistor..

A 78L05 SMD is miniscule, and will provide 5V out even if the input is 8.4V which it could get up to with 2 Li-Ions. And I didnt know it limited current? I thought it just kept voltage at 5V or have I understood them wrong?
For a single cell host, the PICAXE can run fine off as little as 3V up to a very maximum of 5.2V.

Why use resistor ? Select proper battery and go direct !

Do you mean add another battery?. That will take way too much space and will be a hassle to replace. The circuit will only draw barely milliamps from the main batteries anyway.

I can't understand how this would help in protecting for overtemperature
....a built in game would be good though Solitaire is a bit boring, Monopoly would be much better

How could you play monopoly with one LED?! Morse code?

voice recognition and finger print verification to over-ride the shutoff, and solitaire to play while you wait for it to cool.

LEDs are boring.

PT-54 is not boring xD Maybe that can be the overheat light. Will overheat it even more. :eg:



Feel free to suggest ideas for what the LED will do. Maybe it could just flash real slow when its cold and flash faster as it heats up.

 

[Cyparagon]

Yeah sure, PT-54s make great indicator lamps. I Prefer half-megawatt carbon arcs for my "on" indicator though.

 

[Flaminpyro]

I wonder what a light like that one costs ?

Well only 3k I think I'll get one for the stern and one for the poop deck of my new yacht :crackup:

:thinking: maybe I should put one on the bow also...

"Short Arc" On Indicator Ver 2

Edit: 4,000 Watt High Pressure Xenon Short Arc Search Light

 

[nztdm]

Heres a layout for the single-cell build. This is a minimal layout with no calibration trimpot, that will just have to be programmed as good as possible.
The pin that the GREEN side of the bi-colour LED is on, supports PWM output, which means I can make the LED display any colour between red and green such as yellow and orange.

It is very tiny at 8.4mm X 10.6mm

i dont know how high the chips sits atop the pcb but i MAY be able to put one of the resistors under the chip reducing the size by about another 25%


And here is the board for the 2 cell version which needs the voltage regulation circuit.
It measures 12mm X 16mm

 

[Multimode]

Great job nztdm,

I was thinking of making a linear driver controlled by microcontroller so that I could select modes (like the flashlight drivers).
if I go ahead, I'll include your idea of the the temp sensor and LED indicator.
+1

ATB
MM