As a part of the question yesterday that has been complained on its feasibility (I did all the thought using my high school knowledge with little further reading so sometime, idea seemed to be stupid and blamed unreliable by some reviewer over here), I have successfully made a pump control for watering my root-top garden and answer the question myself.
See here (and the linked part 2 as well).
In short, for a certain frequency, the Pi network works as a transformer. It can be tuned to match between any combination of source and load impedance.
That's how a great deal of antenna matching circuits look like.
This particular circuit is tuned to ~3GHz, but the exact properties (input and output impedance) can ...
Have you considered just keeping the ESP8266 in deepsleep and having the reed switch cause it to wake up?
Here's a door alarm project using an ESP8266 which does that:
More discussion here: https://github.com/esp8266/Arduino/issues/1488#issuecomment-205113504
As Neil_UK's answer points out this arrangement is not good for power supply because it will change the resistance value if connected element is not high impedance element.
For power supply, you can use linear regulators like 7805 for 5V supply. You can also find 3.3V version of linear regulators. The higher voltage will be dissipated by mostly heat for ...
So actually if you take Vout, connect it to the + terminal of a device, and the - terminal to GND, the voltage of this circuit will be dependent on the resistance of the device. So what is this arrangement of voltage dividing good for?
It's good for driving very high resistances, where the load resistance has no significant effect on the output voltage. It ...
You should be using a N-channel MOSFET.
Previous answers suggest using a BJT, but BJT will have about 0.6V voltage drop, and the microcontroller will probably read that as a logical 1.
The MOSFET will have almost 0V drop (assuming the current is very small) thus removing that issue.
simulate this circuit – Schematic created using CircuitLab
You should be using an NPN transistor if you are expecting it to work the same as your relay version in your schematic.
You should check how much current is being drawn through the relay contacts when they are closed and the voltage across them when open to ensure you choose a transistor that can take the voltage and current.
Probably around 10k would be sufficient. It is only a pullup for the reset signal, so not super critical. The esp01 board might already have a resistor on reset, in which case you don’t need another.
P.S from what i googled, the esp-01 has no pull-up, so 10k should do it.
Note: your battery is drawn the wrong way up.
I did some deep dive into timing and as result, I modified two values in Tasmota firmware. Problem is not related to HW failure in 99%, but for me it is not yet fully clear if the problem lays in unreliable ESP8266 internal clock or somewhere else.
It appears it can be also related to system actual load that impacts clock, as some users reported that they ...
This simulation does not work in reality.
Current Transformer does not have enough power to driver a high enough burden resistor.
Diodes have voltage loss not accounted in the simulation
Using voltage dividers and dc bias works very reliably but does not offer the clamping of the zener diode, this feature I had to give up.
The "PWM" used in equipment for radio controlled models , is not actually true PWM where pulses are sent at a fixed frequency with an on-time proportional to the off-time betweeh 0% and 100%.
The "PWM" used in RC is actually a a pulse that varies between 1-2ms in width. So for 0%-100% it would be 1-2ms. But if it's -100%-100% then it ...
I fixed it. The value for R3 at 10kOhm on the RX-line was wrong in my schematic and I didnt bother to check while putting the board together. Everything is working as intended now.
Thanks for your input!
At the very least, you nead a different 3.3V source. If it tries transmitting anything, just the ESP8266 will draw over 100 mA, which is the maximum the LDO in CP2102N can provide.
Also, you cannot just short two voltage sources and call it a day - you need to protect those outputs against reverse current. CP2102N is fine, since it handles both directions on ...
Your MOSFET will not turn on fully with Vgs=3.3V. You can use a 74HCT logic gate with a 5V power supply to convert 3V3 into 5V. The input voltage thresholds of HCT gates will read 3V3 levels correctly with good noise margin. Use a gate resistor on the FET, like 1kohms, to slow down the switching.
Since the load is inductive, the FET absolutely needs a ...