Temperature Sensor

[QUAZ HOLT]

A circuit to be install in a magnet or stator coils. This would allow the temperature to be monitored while the generator was operating. Great idea I thought so into the skunk works I go. Now the parts to do this are all on my desk. The next hard job is to find them. These parts are small, smt there are called. I think it stands for small miniature thingy.
Heres the schematic of the control.

The main part of this circuit is the thermal sensor Microchip tc1047a -40c to +125c. This chip is a sot23 package and cost about .95 cents.
Some pictures of the small parts.

These small circuit boards that I made allow me to use surface mount components (Oztules you would like'em). The small trimmer is used to adjust the alarm level.

This is the finished unit. Its works on a 3.6 volt rechargeable lithium cell and draws .22 milli amps. It should run for a long time per charge. Bill

[Saidrich]

Another project completed on a rainy day. Good for you Quaz.

[willib]

very nice

a while back i bought a temp probe at the dollar store ,it has four led's labeled

all ok

getting warm

better shut me down soon, she's a gonna blow captain and there's nothing i can do about it.

bang ping swish, run for your life

[commanda]

Hmmm.... small miniature thingy; will have to remember that one.

I've just thrown down a similar circuit for a temperature monitor for batteries. I added a meter movement to mine to display the actual temperature, as well as a switched output to feed my dump load controller. True to my penchant for complete overkill, I used a quad op-amp and 3 trim pots and a precision voltage reference..

Amanda

[oztules]

Nicely done.......

You see Bill the difference is that you know what your doing...

(how can you hold of those itty bitty bits and not burn your pinkies)

.............oztules

[dinges]

Good idea, I was planning on installing a temp.probe in my 10ft stator too.

However, I will only insert the temp.probe (don't know exactly what type yet; a common diode (1N4148), NTC or whatever. Any silicon junction can perform the temp. monitoring task, and we don't need super high accuracy & linearity here. Just a 'watch it, it's getting very hot in here!' would be enough, for me.

I will simply install two brass bolts to the outside world for connection of the temp. measuring equipment. That way, I can always choose whether to use the temp. probe or not.

Maybe that's the reason so little work gets done here: no more rainy days. 30+ deg C for several days now. I'm not complaining. PV works fine

Peter.

[BigBreaker]

A microcontroller can do this for multiple signals, including temperature, tach, voltages and currents in one programmable chip.  It's worth it for everyone to read up on their capabilities.

[kitno455]

i wonder how close you can get the sensor to the coils? i mean, it will eventually start to develop a voltage from the mags passing by?

allan

[QUAZ HOLT]

Willib, I have made one that monitored the fire temp. This was to tell when to add wood. The only problem it did not have an on/off switch, needless to say when it started beeping it woke me up and I thought it was a fire alarm. Stumbling around looking for what was that beeping in the dark till I came to my senses. Duh ouch Bill

[QUAZ HOLT]

Oztules, the secret is tiny metal fingers. Bill

[ghurd]

Bill, Want some (25?) SMD 723s?

G-

[QUAZ HOLT]

Peter, these thermal chips make life simple. The number is a (TC1047A by Microchip (tm)

and here is a basic circuit.

Just subtract 500 mv from the voltage and the Celsius reading. Calibrated for you to 1 degree. You could add a offset like Commanda talks about to get a direct readout. Bill

[QUAZ HOLT]

Kitno455, Sounds like your idea needs testing. Will give it a try to see if it has any effects on the output. I tried a RF transmitter in close proximity to circuit and this test seems to have no ill effects. Bill

[dinges]

Had something like an LM35 in mind. Guess it's more or less the same. Don't need super high accuracy here, just a rough temperature indication.

With the correct use of two potmeters (one for offset of the 500mV, the other for 'rescaling' of mV to deg.C) it might even be possible to have direct 'deg. C' readout on a DMM display?!

Hmmm, your IC doesn't even need a rescaling of the output, only an offset of .5V; i.e. connect a potmeter to +3.6V and to gnd; adjust the wiper to .5V, connect ground of DMM to the wiper. Connect the + probe of the DMM to the output of the IC: finished; direct degrees C. readout on a DMM! Will look in the datasheets for the LM35 whether it's a simple with that one too.

But, with long lines from windmill to the readout, it may perhaps be necessary to lower output impedance of the temp. IC.

Hmmm, didn't know Microchip made temp. sensors too. Thought they only made microcontrollers (PICs)

Peter.

[QUAZ HOLT]

Ghurd, Have not used that ref. I used the 385 2.5v for this one. Three lead TO92. like a small leaded plastic transistor. What current do 723s need and what package do you have. My reference circuit total is .03 ma . Had to steal this one out of and old circuit. It always seems that things are held up for some 50 cent item. Bill

[QUAZ HOLT]

This point you bring up needs some testing. Will make a test at 100 feet from my solar cell and then test reading at end of cable. Will post results. Good dvms will not load the sensor much and rescaling the meter could be done by a felt pen and tape. These type of circuits need to be displayed so others have lots of options when making sensors. Lots of stuff in my brain that needs to get out. Bill

[wooferhound]

If you put a temperature sensor in the stator, it will have wires going to it. The magnets passing by your wire would generate an AC voltage that would make your readings wildly inaccurate.

[kitno455]

thanks- that is what i was trying to say.

allan

[commanda]

For the sake of completeness, heres the circuit

Have done the pcb layout but not built it yet.

Amanda

[QUAZ HOLT]

It's worth it for everyone to read up on their capabilities. BigBreaker, I dumped a stack of books on my brothers desk. I would say 2 feet tall and said "read this and you will be tested on it in the morning." Most of that stuff has a horrible learning curve. Post the circuit and the code. Share the knowledge and get lots back. Bill

[QUAZ HOLT]

You guys just cant wait for the test. It works good in practice. Wonder if it will work in theory. Will see if you are correct. Bill

[willib]

its a very steep learning curve , but the payoff at the top is very rewarding

i made my own programmer , designed it too , wrote the programmer code also , i had to modify the code to program the Pic 16F88 because it was a newer chip at the time

[RP]

Use the tiniest lead wires you can to the sensor and twist them very tightly.  This way you should be able to cancel most of the induced current in the wires,  Also consider orienting the device so its flat face is parallel to the axis of rotation (like if it was stuck to the edge of a magnet).

You may actually want to do some testing on this before commiting it to resin!

Since any induced current will be AC, you might be able to strip it off with series inductors and parallel capacitance across the wires.

[QUAZ HOLT]

The test results are in. No magnetic effect with this sensor. I believe that common mode rejection in the circuit eliminates low level noise. Very thin twisted lead wires and proper placement allow this sensor to operate without interference. Quality Control, pass. Now beta testing. Bill

[QUAZ HOLT]

RP, correct. Did, did, done and doing. Thank you for your input. Bill

[ghurd]

Its not that they could fit this circuit, its just I don't want them!

They were an accident. LM723 specs? Forget the package #, and they are at the shop.

Like most people, I can't use (see) them.

They simply need a good home with a tiny soldering iron, in the US or Canada.

Yaw-who to ghurd1

G-