Super Simple Temperature(Heat) Activated LED/Cooling Fan Circuit (NC or NO??)

           Super Simple Temperature(Heat) Activated LED/Cooling Fan Circuit 

                                    (Normally Open or Normally Closed??)

I was looking for a simple temperature controlled cooling fan circuit for my prototype inverter, and was excited to run across one on YouTube from electronicsNmore called "Super Simple Temperature(Heat) Activated LED/Cooling Fan Circuit."

Great! Simple! 

Just like what I was looking for.

Super Simple Temperature(Heat) Activated LED/Cooling Fan Circuit from electronicNmore

So, I ordered some 45 degrees C (113 degrees Fahrenheit) bimetal temperature sensors that I found on Amazon "High Quality KSD9700 250V Bimetal 45 Celsius NC Temperature Control Switch Pack Of 10." 

The parts arrived promptly from China via U.S. Post Office, so I immediately set about getting the circuit up and running on a breadboard. 

However, it did not work! I was very puzzled - this is a very simple circuit to build.

I checked the video comments again. Sure enough, he said "Normally Closed" sensor.
  
  

Normally Closed sensor for Super Simple Temperature Activated Cooling Fan Circuit

  

So, I thought I would do a simple test to see if the sensor was really "NC" (Normally Closed), or perhaps the vendors sent "NO" (Normally Open) by mistake. A direct connect of positive to negative and directly to the fan should tell me. If the sensor is Normally Closed, then the fan should com on without the breadboard set up. 

The fan did not come on. It would appear that the vendor sent Normally Open temperature sensors instead of Normally Closed sensors! 

So, I had the wrong temperature sensors for this circuit. Let me see, my options were that I could send the sensors back to the vendor, but I got these fairly cheap, and the postage would just add to the cost. Or, I could look for a "NO" version of the YouTube circuit. I thought i would be easy.... wrong thought. 

I searched YouTube for a "Normally Open" version of the cooling fan circuit only to be disappointed. One blog said just buy the "NC" version if you have an "NC" circuit. Well, I already did that. How many times would this part problem happen?? So, I spent a few more hours on Google looking for a "Normally Open" version of this simple circuit without finding one.

After hours of searching, I was at a loss. I took electromagnetic theory in college, but other than that, I have no electronics training. So, writing up my own circuit is not something that I normally attempt. Then I remembered a comment from Mr. Swagatam Majumdar on his "Low Battery Indicator" circuit. You could reverse the polarity of the circuit in order to convert it to a "High (Overcharge) Indicator" circuit.



 

Converting a Low Battery Indicator into a High (Overcharge) Battery Indicator

Maybe I could turn the super simple temperature controlled (Normally Closed) circuit into a Normally Open circuit.

So, I gave it a shot. I reversed the positive and negative on the cooling fan circuit, changed the polarity of he transistors, and reversed the diode polarity.

And it worked!

Super Simple Temperature(Heat) Activated LED/Cooling Fan Circuit Normally Open

I am thrilled. Now I have a simple temperature controlled cooling fan circuit no matter if I have NC or NO type sensors. Excellent.

Ideally, if the circuit fails, you would want your cooling fan to be able to come on at start-up by default. That will be one of the things that I will test for. My guess is that the "Normally Open" sensor will not fail over when the sensor fails, but might fail over if I lose a transistor.

I have not checked yet, but you probably do not need a circuit for the "NO" sensor. I am thinking that it should work with a direct connect. But, it is good to know that electronicsNmore also provides an indicator circuit in his video, and the circuit can be used for whatever your needs may be.

Thank you to electronicsNmore on YouTube, and to Swagatam Majumdar at Homemade Circuit Just For You.

Video from electronicsNmore:

Amazon "High Quality KSD9700 250V Bimetal 45 Celsius NC Temperature Control Switch Pack Of 10." 

Amazon "10 Pcs Bimetal Temperature Control Switch Thermostat 40C N.O TLRS9700"
." 
YouTube video link:

Super Simple Temperature(Heat) Activated LED/Cooling Fan Circuit

Update 12/16/2014:   

O.K., new thought there. I am thinking I can use his circuit with a slightly higher temperature for a automatic shutdown to prevent overheating. Maybe place it downstream of the "On" LED (part of the inrush protection circuit), and downstream of the fan so that the fan keeps cooling after the circuit shuts down. He also has an indicator light circuit in this video that I can use when the shutdown kicks in. Great. Don't want to start a fire or ruin the parts....

Homemade Modified Sine Wave Power Inverter(350/500w) on a Breadboard

I am very excited to have finally gotten this hefty little circuit working on a breadboard today. 

I first saw this on a You Tube video called Homemade Modified Sine Wave Power Inverter(350/500w) by electronicsNmore.

 
O.K.,  first I have to admit that I was not able to get it working the first time through. I had let it sit on the back burner while I worked on some other things. But, today, I gave it another shot, and am happy to see it working from a breadboard.

 The circuit was designed by John Parfrey, as is indicated in the schematic.

Homemade Modified Sine Wave Power Inverter(350/500w) by John Parfrey

Second time through, I wanted to test that it was functioning by leaving out the 7808 voltage regulator, just to make sure that it worked. After confirming that it did work, then I add the 7808 voltage regulator, upside down on the breadboard, simply because the schematic shows the input to pin #1 was to the right, and I wanted to visualize that. The remaining parts are laid out pretty much as the schematic has it.


There are at least two things that do not match to specifications (on my breadboard), the transformer and the 0.1uF electrolytic capacitor (to the left of the schematic). The design calls for a 10-0-10 center tapped transformer, and I am using a 12-0-12, 4 Amp transformer. Also, I do not have the 0.1uF electrolytic capacitor, and am currently using a 1uF electrolytic capacitor (until I can order the correct capacitor).


Otherwise, I am using the STP55NF06L mosfets, for the 500 watt version (as is shown in the schematic).

I did observe that the waveform is indeed a modified sine wave (using a 4 watt light bulb):

Modified Sine Wave from John Parfrey's Power Inverter design

You might also notice that the frequency is nowhere near the 60 Hz that I want it to be, indicating that the change to a 12-0-12 transformer may require less resistance than indicated in the schematic. You might note that ElectronicNMore YouTube video indicates that he is using an old microwave oven transformer, so the design can be modified successfully. Other factors that can affect frequency would be that I am using the 'cheap' version of the 4017, which does not operate as effectively as more expensive versions, and my battery amperage on this breadboard is minimal. (You can see from the breadboard photos that my power source is AA batteries. I also test with a 7 Amp Hour battery, and a 22 Amp Hour battery). A more powerful battery under a larger load would be more likely to deliver a different frequency.


Being relatively new at this, I think one of my initial problems was that I had not seen the breadboard on this one. So, I will add breadboard pics for others who may want to try it out.

Homemade Modified Sine Wave Power Inverter(350/500w) on a Breadboard

 
 Here is a close up view with the positive rail at the top:

Homemade Modified Sine Wave Power Inverter(350/500w) on a Breadboard02

Here is a view from the other side, which shows that after the 7808 was added (upside down), I used the inner rail for the positive side downstream of the 7808:


 

Homemade Modified Sine Wave Power Inverter(350/500w) on a Breadboar03

Finally, I am including a link to the You Tube video that shows the inverter in action.

You will want to read the text following the video, as ElectronicsNMore also added circuit inrush protection, a fan, and a low battery indicator. You can search the ElectronicNMore video channel for the design (and video) regarding circuit inrush protection.

Also in the video, he demonstrates his finalized project, using a both a hand held sander and high power garage light. You may notice in the video, he is using the 350 watt version of the schematic (by using IRF3205 mosfets). Nice to see a video of the inverter in action.

You Tube Video "Homemade Modified Sine Wave Power Inverter":

Schematic Reference

   Modified Sine Wave Mosfet Inverter Schematic by John Parfrey
 
Videos from electronicNmore:
 
   Homemade Modified Sine Wave Power Inverter(350/500w)
    
   Simple/Effective Solution To Inrush Current Problems

   Simple 120/240 VAC LED Power Indicator

   12V Lead Acid Battery Low Voltage Alarm Circuit 

   12V Lead Acid Battery Overdischarge Cutoff Circuit

  Super Simple Temperature(Heat) Activated LED/Cooling Fan Circuit

   Under Voltage/Over Voltage Cut Off Circuit (12vdc/120v/240v) (Video)

His temperature activated cooling fan (above) uses the bimetal sensor normally used with NiMH battery packs, available on Amazon and Ebay. Here's a link to an Amazon listing:

Amazon (Normally Closed??) "High Quality KSD9700 250V Bimetal 45 Celsius NC Temperature Control Switch Pack Of 10." 

Amazon (Normally Open??) "10 Pcs Bimetal Temperature Control Switch Thermostat 40C N.O TLRS9700" 


YouTube video link: 
Electronic Projects Circuits Blog Article:

   Battery voltage monitor circuit by LM339

Homemade Circuit Designs Just For You Blog:

   Under Voltage/Over Voltage Cut Off Circuit (12vdc/120v/240v) (Blog)

  

100 Watt Inverter Circuit Schematic using Pulse Width Modulator IC SG3525 (my review)

100 Watt Inverter Circuit Schematic using Pulse Width Modulator IC SG3525

                                  (my review)

 Here's a nice little gem that I found on the circuitsgallery.com web site, designed by Khaleel.

 

 

12v to 230v Inverter Circuit Schematic using Pulse Width Modulator IC SG3525 by Khaleel

Fairly straightforward, and fairly easy to build. You have to watch for a few resistors that are 1/2 watt, some capacitors have strange terminology, and some of the symbols are explained in the text portion. So, be sure to review the article if you want to build this one.

 

I currently have this one running on the breadboard.

 

The design calls for a 12-0-12, 5 Amp transformer, but I only have a 4 Amp transformer, so mine is not quite to specifications. However, it still works. The Rt is adjustable if it is replaced with a preset or potentiometer. That adjustment was necessary (for me), due to my 4 Amp transformer. At any rate, the final result was that I was able to adjust to the 60 Hz frequency using a 4 Amp transformer and adjusting Rt as a potentiometer. (The 4 Amp transformer requires less resistance at Rt.)

 

The Pulse Width Modulation (PWM) automatically adjusts for powering devices with various power needs. I currently have it running from the breadboard, but I suspect I may build it with two outlets, or otherwise I would suspect that I should be able to use an extension cord with lights of various voltages.

 

Let me see, the only drawback of a circuit this straightforward is that the waveform is not a sine wave form, nor a modified sine wave form. Which means, it may be a bit harsh to use on sensitive electronic devices. I would only use it for lights.

 

Still, I am short on emergency lighting, and need some practice adding things like a fan and some circuit protection. So, I intend to build a finished version of this little one, simply for those reasons. 

 

Nicely done, Khaleel. I suspect this would be a quick build for most folks. This could be useful for emergency lighting, or for lighting the workshop. Thanks.

   

Reference:  

12v to 230v Inverter Circuit Schematic using Pulse Width Modulator IC SG3525

 

 

Make a Solar AA Battery Charger by TL497 (my review)

   Make a Solar AA Battery Charger by TL497 (review)

This is a project to use a solar panel to charge a small battery, such as a NiMH battery in the 3V to 9V range, with mAH measuring between 1,000 to 2,000 mAH. It's just great to see that they have also included the PCB layout for you on this design. Something I don't see very often.


http://www.eleccircuit.com/make-solar-aa-battery-charger-by-tl497/

The TL497 integrated circuit is a fixed-on-time variable-frequency switching-voltage-regulator control circuit. It features frequency control and current limit sensing, among other things.
 

Make a Solar AA Battery Charger by TL497 from Electronic Projects Circuits

First things first, I have to point out that I am not using their circuit as designed.

The circuit calls for a 5V 100 mA solar panel, and I only have a 6V, 1 watt solar panel available. Secondly, I am trying to use it to charge 4 AA NiMH batteries, rated 2500 mAH, which is also not to specifications. Third, it calls for a 40 uH inductor. I don't happen to have a collection of inductors, but I do have a few toroids available.

Be aware that I am not using this circuit as designed, so your results may be different.

Even with my changes, it looks to be working for me. However, I hope to be performing more testing on this unit.

The circuit seems to work well for me using AA batteries when I cover the toroid about 4 times, or for about 90 turns of 22 guage wire.
I don't have a micro Henry meter, so I cannot specify what I have in those units at the moment.

I am testing in ambient light, such as what you might get in the shade, or when indoors.

At the moment, this one appears to perform better than the Solar Charger Circuit Project, and also appears to out-performs the 3 Volt to 9 Volt Converter (with either a 4.5V solar panel or a 6V 1 watt solar panel (that I have posted elsewhere). That is, sometimes it appears to perform better than the 3 Volt to 9 Volt Converter, sometimes not.

I will be doing more measurements, and trying to figure out the best way to test even though I don't have everything to specifications.
 
Previous Articles:

 Solar Charger Circuit Project (my review)

  3V to 9V Conerter (my review)
   
Currently testing for parallel charging, which is typically harder to do than charging in series.
You may get better results from charging in series.

I will also be looking at variations, such as number of turns on the toroid, etc.


Update Sep 7, 2015:

I have yet another AA charging circuit posted here:

Indoor Ambient Solar AA NiMH Charger & Night Light

Solar Charger Circuit Project (my review)

                        Solar Charger Circuit Project

Take advantage of the sunlight and use it as a power source. It can at least save on electricity prices continuing to rise, or be of help on a camping trip, or while traveling.

The Circuits Schematics Electronics blog has a schematic of simple power plant can be created and used to fill your motorcycle battery, your ebike battery, or for emergency lights:


     http://circuitschematicelectronics.blogspot.com/2012/06/solar-charger-circuit-project.html


The circuit is designed to charge a 12 volt battery, but I wanted to see if it would simply charge 4 AA NiMH batteries (4 to 5.6 volts).

So, I went about putting it together on a breadboard.
  
 

Solar Charger Circuit Project from Circuits Schematics Electronics

I was curious if I could use this to charge 4 AA NiMH batteries, and was not disappointed.
Therefore, first off, I have to point out that I am not using their circuit as designed.

Notably, the specifications call for a 4V, 200 Amp solar panel, and a ferrite rod. I did not use either. I do not have the BY207 (Diada 5 Ampere diode). Nor am I using a 12 volt battery.

You can use a ferrite rod, possibly from an old AM radio.  I don't have a ferrite rod, but I thought I would try it with toroids, as toroids I do have.

Also, the circuit calls for a 4V, 200 Amp (total) solar panel, but I only had a spare 6 volt, 1 watt solar panel.

The specifications call for a BY207 (Diada 5 Ampere diode), which I do not have.
Instead, I tried a 1N4735A, 6.2V, 1 watt Zener diode.

 The circuit is designed to charge a 12 volt battery, but I wanted to see if it would simply charge 4 AA NiMH batteries. So, I went about putting it together on a breadboard.

However, I did get some results. At first, it did not appear to generate enough voltage or amps for my AA batteries. With a little experimentation with the number of windings on the toroid, I was able to get some decent figures for the voltage required to charge my AA batteries.

It appears to respond to an increase in the number of turns of wire on the toroid.
I have 22 guage wire available, and a blue toroid from Digi-Key. The toroid spec out as Inductance Factor of 5.46µH and Permeability of 4300.

The circuit seems to work well for AA batteries when I cover the toroid about 2 times, or for about 60 turns of 22 guage wire. I don't have a micro Henry meter, so I cannot specify what I have in those units at the moment.

Again, this is not how the circuit was designed to be used, but I was happy to see that I could modify it for this purpose.

Currently, I am testing in ambient light, such as what you might get in the shade, or when indoors. This one appears to under perform both the use of the IC 497, and also under performs the 3 Volt to 9 Volt Converter that I have posted elsewhere.


However, it is much simpler to build, it is using parts that are generally available, and again, I am not using the circuit as designed. But, I was happy to see it respond to charging AA batteries.


Previous reviews:

   Make a Solar AA Battery Charger by TL497 (my review)

  3V to 9V Converter (my review)


Currently testing for parallel charging, which is typically harder to do than charging in series.
You may get better results from charging in series.

I will be looking at variations, such as number of turns on the toroid, serial vs. parallel charging, ambient light, etc.

Update Sep 7, 2015:

I have yet another AA charging circuit posted here:

Indoor Ambient Solar AA NiMH Charger & Night Light