SayantanM4

The capacitance of the variable capacitor will determine the frequency value of transmitted fm signal. Actually this requires some trial and error methods. You have to take a radio and set to a particular frequency such that it is being used by no other channel. Now slowly rotate the variable cap and you'll find a point where the radio sound becomes dead silent or it can make a very high pitched sound nearby the frequency. That point will be that operating frequency. The cap value has a highest value of 40pF

Yes the AT commands take care of all of them . there is a complete list of AT commands available on the google. Actually the entire thing happening in this AT commands are quite complex. We just use them to finish our task. Actually a complex process happens in the hardware. The SIM used here is a normal 2G/3G SIM, nothing special. I have not tried 4G SIMS yet. Thanks Sir!

bro..enter your ssid and pass of your router here...in the starred areas, at the beginning of the code

hey man you had set baudrate in the serial monitor at 9600...set it to 115200 then press rst on nodemcu and then see

please download the fzz file attached there and open up code tab

Thanks Sir

Thanks for the information Sir!! I'll keep that in mind always, and by the way, you can use either 817 or 4N35 or MCT2E, just reading about the inside BJT characteristics from the datasheet is necessary...

The IR Led receives about 4mA of Current and that is sufficient for its glow...the BJT part is fully seperate...it has no dependance on that 4mA...it is a fully seperate circuit and that bjt is controlled by the IR light falling onto it's base, we apply seperate KVL equation for that BJT part, .....yes that BJT is actually saturating and 1K is good for that

Yes.. Good job.. actually I used a different library... You can use your version too... Just modify the temperature finding part and you are all set... Cheers

No....line voltage is not used to energise the relay...5-6V DC signal is used to energise the relay coil..look at the circuit carefully...it is a normal 5V relay

Thanks... You can use this in your arduino and home automation projects

The circuit has complete isolation and hence safety... The ir and Bjt side is fully isolated and if there is any error on the Ac line the user will be safe.... I've done previous experiment and observed datasheets of the optocoupler and found that the ir led will glow at a forward voltage of 1.2 to 1.4V...beyond that will destroy the ir.. So as current is not that too high I used a standard 1k resistor and found the forward voltage of 1.2 across the ir led... The second ir led is a Base current limiting resistor and current there is as low as 20-40 mA...so there also I used a 1k resistor and used a Darlington configuration and found the relay being driven properly

https://www.instructables.com/id/Controlling-Appliances-From-Smartphone/I've also done a similar project... Cheers..

where the other end of the 10K resisitor ar gpio 15 would go???

where the other end of the 10K resistor at gpio 15 would go???

Thanks bro..I'll check your instructable

Yes it works just fine..there are two videos describing it at the last step..Absolutely it would be best with wood with air tight gaps..but I did not have the required tools right now with me so I managed with cardboard..

You can also use the proposed structure..add some motors too. so that it can be called to your side

LOL..Yes it is a bit awkward looking due to lack of proper parts..anyway it's just a sort of tutorial..you can make it even better by attaching display wheels,etc..

I would like to power the nodemcu with a good 9V battery (eg Duracell or any good company.. Not the Chinese cheap ones) or with a Li battery( with voltage rating greater than 5V but less than 12V) along with protection circuit( protection circuit is mandatory for Li batteries).

Thanks 4 the suggestion

yes sir..sorry I don't have it actually now..I will update that as soon as possible...sry again

Thank you Sir..you can add more sensors like BMP180 or BMP280 for pressure and altitude...there are lot of documentation and videos regarding it..

Thanks Sir

Ha Ha LOL...caught it right bro....Just cut my index today.... XD

Yes Sir... there are actually many drawbacks of this system....but it would be helpful in a less congested area... also the 20cm can be changed to any value as you want in the code...

In Step 5 it is attached..it is recommended to see in desktop...and I used that for my version of this bot

Attached in step 5...recommended to open in desktop... and mine one runs on that code.

Yes..attached in one of the steps

Thank you sir! You can also extend that app and extend the code a bit which can also control your AC and other stuffs. If you face any problem relating to the above instructable feel free to comment or mail at mightysanu123@gmail.com.

nice one bro! I actually tried this for a cheap number game, u can use 4026 for many purposes like a visitor counter,etc.

the formula includes R1, as per calculations...and yes it will not be a perfect square wave ...but it will work fine for feeding clock for counters and flipflops

Yes that's good, also I used a frequency to test it which was not used by any local radio station. For making it beyond normal typical frequency...normal radios might not have that frequency. In that case a separate receiver must be made...I will try to make that one in a few days.