# Tag Info

17

Lots of problems with your circuit: T1 is used as a emitter follower. Its output will therefore be less than the 3.3 V input. Figure 700 mV for the B-E drop, and the maximum the gate of Q1 is driven to is 2.6 V Q1 is used as a source follower. Its output will thefefore be less than its input. Unlike a BJT, as T1 is, the G-S voltage is not so easily ...

16

Here's a slightly different approach in stead of a Lua vs. Python shootout: Six of the most popular ESP8266 "runtimes": AT Command SET. Popular when the 8266 is paired with another MCU. Communicates via the serial port. ~64k of 128k RAM available. MicroPython. A MicroPython script interpreter with user friendly GUI that can be accessed via the serial ...

13

which is best for fast switching do I need to use MOSFET driver IC such as ICL766 with IRFZ44n or is it better to use lower VGS MOSFET such as AO3400 You don't want fast switching to drive LED strips! If the FET switches in a couple tens of nanoseconds, you will send very high di/dt currents into your wires which will radiate electromagnetic interference ...

12

Resistors are the wrong way to do what you want. Step back to your actual problem, leaving out how you think it should be solved. There are basically two reasonable approaches to making 3.3 V and 5 V power from 9 V. These are a linear regulator and a buck converter. A linear regulator is like a self-adjusting series resistor. It keeps the output voltage ...

12

The diode is there to protect the opto-LED in the event of a reverse polarity connection. The HF11L datasheet states that the absolute maximum reverse voltage for the emitter (meaning the IR emitter, the LED) is 6 V. Typically a 5 V supply would be used for the MIDI driver but it's worth being careful. In your case pretty well any diode - including an LED ...

11

9V batteries are great for smoke alarms, but pretty shocking for anything else. The capacity of a standard PP3 (alkaline) is about 400mAh and has an internal resistance of around 5 Ohms (in fact some low duty ones internal resistances closer to 20+ Ohms). So basically not a lot of energy, poor current capability, and lots of energy wasted internally. If you ...

11

It's simply an AF (audio frequency) coupling capacitor, removing any DC that is on the signal.

10

You have two problems 1) The output you see (ets Jan 8 2013,rst cause:2, boot mode:(3,6)) is printed by the startup (bootloader) code. After that, the communication continues on a different baudrate (IIRC either 9600 or 115200 baud, depending on the firmware revision). 2) The 3.3V output of an FT232 can't deliver the current required by an ESP8266: not by ...

10

Also note that that battery is 3.7 V nominal voltage. Fully charged it will probably be 4.2 V. Way too much for the ESP8266. Conclusion: you need a voltage regulator. Look for a buck boost regulator like this: - Or this: - Or this: - Or this: - Or this: - Or try googling "low power buck boost 3.3 volts 150mA" yourself EDIT SECTION A really small ...

10

The ESP8266 chip is relatively new to the market (circa 2014, I think). So it's short market availability has limited its adoption somewhat -- some early adopters have chosen it, but that's usually not a benefit to high volume, low cost designs. There are also many more well tested chips/modules that have better documentation and better support. TI, Silicon ...

10

The radio contains a voltage controlled oscillator that is locked to an external reference oscillator using a phase locked loop (PLL). This results in a very precise high frequency signal for the radio on the chip. The radio will use one or more oscillators to upconvert and downconvert the signal to the required RF channel. This will be entirely distinct ...

10

The first RC does indeed act as a low pass filter. The second capacitor (the one on the right), combined with the load impedance presented by whatever is connected to the audio out, acts as a high pass filter. Together, these two filters act as a band pass filter.

9

There will be gaps around the manhole cover, either air due to sloppy fit, or in the concrete/bricks. The 2.4GHz exploits those gaps with its 100cm/(11 * 4) = 100cm/44 = 2.2cm quarter-wavelength to leak out. The 433MHz, 6 times longer in wavelength, has exponentially tougher problem in "leaking out". EDIT Here is link to prior answer on shielding, ...

9

The ESP8266 ADC is not really a very good one for instrumentation purposes. I believe it's not very linear (especially for voltages near 0V) and the internal reference voltage might be +/-10% or worse tolerance- loosely specified (with no accuracy limits that I can see, kind of a "bonus" functionality that you shouldn't depend on too much for serious ...

8

You should show us what circuit you've tried, but your simplest solution is this case would be a single P-channel MOSFET. simulate this circuit – Schematic created using CircuitLab When your ATtiny's GPIO pin is high, the MOSFET will be switched off, and when the pin is low the MOSFET will be switched on. Make sure you connect the Drain & ...

8

ESP family isn't a AVR! The Library you refere to is a Arduino IDE (Integrated Development Environment) library. The Arduino IDE has a hardware layer that gives it the ability to utilize several MCU arhitectures that isn't AVR, but they share the programming environment.

7

The device you have does not provide an analog output- it is a simple resistance comparator (bridge circuit into an LM393 inputs): Since the LM393 has an open-collector output, your loading it will cause the LED D2 to turn on and will reduce the voltage substantially. You can use the output as a logic signal into your micro, but there is no analog signal ...

7

Using a P channel MOSFET to switch the power is reasonable, but the way you propose to drive the gate is not. The microcontroller can drive the gate basically to ground, so turning the FET on is no problem. However, the micro can only drive the gate to 3.3 V, not to its source, so may not turn the FET all the way off. You want the gate to swing the full 0 ...

7

For critical systems, a failsafe circuit is used that has to be toggled continuously to activate the relay. The GPIO pin is toggled in the main software loop (typically) after doing all the normal processing. If the loop stops, the toggling stops and the relay is deactivated. simulate this circuit – Schematic created using CircuitLab C1 blocks DC ...

7

No this is probably not a sensible approach because the N channel MOSFET is wired as a source follower and cannot therefore produce a voltage output that is any greater than the gate drive voltage. In fact, with (say) 5 volts applied to the base of T1, the emitter will be about 4.3 volts and this drives the MOSFET gate. However, the MOSFET needs maybe 4 ...

6

When you hold the button down and the micro drives the ON/OFF line low, there's a low-impedance path directly from the battery, through the I/O protection diodes on the SENSE pin of the micro, to its power bus — this is a very bad thing. There's another path through your external diode and the ON/OFF pin, too. At the very least, you should have a ...

6

The antennas that you are using for the 433 MHz link are very marginal. While there may be regulatory issues at play, if you can increase the gain of both antennas, you would see far better performance on the 433 MHz link. At the very least, build a 15 dBi gain yagi antenna for the receiver and point it at the transmitter.

6

Unless you have a better than 1C temperature reference, I would not bother trying to get a higher absolute accuracy than what you get using nominal data sheet info. If you need a true high accuracy temperature reference, use a thermal couple or Platinum temperature sensor (RTD). If you want to try this anyways: The reference voltage, if your info is ...

6

The datasheet states a the minimum Vin must meet 2 conditions, one of them being: $V_{in} >(V_r + 3\%) + V_{DROPOUT}$ which for a 3.3V regulator becomes $V_{in} >(3.3V + 3\%) + V_{DROPOUT} = 3.4V + V_{DROPOUT}$ So, that leaves 100 mV to be "used" for dropout. You cannot use FIGURE 2-12 and FIGURE 2-13 from the datasheet to determine the ...

5

The 3.3V regulator on a ft232 is not that strong. 50 mA or so at best. The ESP is very power hungry compared to it. You need a better regulator. This is to say, the regulator on the FTDI is being overloaded, and the whole thing is losing power, essentially brown outs. The FTDI runs off the 3.3v internally, so when the regulator starts failing to regulate due ...

5

Your resistors are limiting the current of all your loads. The OLED module is the most sensitive to such limitations. As stated in the comments, you need a voltage regulator.

5

Currently I don't have the ESP8266 module to test this, but I think that you can use CH_PD pin to turn it on and off. No additional components required, just connect ATTiny85 and ESP8266 directly to your power source (3.3V from LM317) and one of the MCU GPIO pins to the ESP8266 CH_PD pin. When you set CH_PD pin high (3.3V), ESP8266 should turn on. And when ...

5

This probably comes down to one of two problems: You flipped some pins on the transistor. If I remember right, on a TIP41 the left pin is the base, the center the collector, and the right the emitter. This is when viewing with the black part of the package towards you and the pins down. Of course don't take my word for this. Check the datasheet. The ...

5

simulate this circuit – Schematic created using CircuitLab Figure 1. Voltage detection circuit. I suggest that you need a circuit to hold the reset pin on your micro until solar output is high enough to reliably power the circuit. Figure 1 uses a comparitor to do this function. When the supply voltage divider, R3 - R4, exceeds the R1 - R2 setpoint ...

5

"Only" 250mA is not the word I'd use when you want to drop up to 345V (if full wave rectified) - I'd like to hear you managed to dissipate 80+ Watt in a linear regulator. The 2 common options are a) full wave rectify, and use a buck converter to drop to 5V (addendum by bss36504: flyback converters do both) b) Use a transformer to drop the AC voltage first, ...

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