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4

In my opinion it is NOT SAFE, if your 18650 Battery Shield also charges the battery. Anyhow some pages state that it is possible to charge LiFePo4 batteries with 4.2V instead of the recommended 3.65V. https://www.powerstream.com/lithium-phosphate-charge-voltage.htm LiFePo4 batteries have a smaller energy density and therefore capacity. Thus those are not as ...


3

I would suggest using a 12V controller, and then adding a 3.3V switching regulator using the 12V supply. That would be 2 off-the shelf components and you're done.


3

If you put three resistors of the same value in series, then you would get equal voltage division between them. But chips are not like resistors. Their current usage is not constant and typically vary by orders of magnitude even within each clock cycle. See why this would be a problem? If you have good 3V batteries that supply 3V up to the maximum current ...


3

9v batteries are incapable of supplying enough current for a motor; their best application is tiny-current, standby devices like smoke detectors. You need a power supply that can deliver much more current than the 9v brick can. 6 AA cells in series would do much better. 6 pairs of AA-cells would give you longer run time (each 2 cells in parallel; the 6 ...


3

Unless you connect the ground of your ATTiny to the ground of your USB UART interface there is no circuit for the electrons to flow around. It works when powered from the computer because everything shared the same ground connection.


2

As is described in this post from the arduino forum, There is a MOSFET switch in series with the USB connector +5V input line. If the battery booster 5V output is connected to the USB input jack, then it will automatically power the UNO whenever power is disconnected from the barrel jack, and will be automatically disconnected whenever at least 7.0V is ...


2

If you scroll down on that page you link to you can see the power circuit. It uses an XC6206 voltage regulator which has a maximum input voltage of 7V and a dropout voltage that could be as high as 680mV. So you can feed between about 4V and 7V in to the VIN pad and it will step it down to 3.3V. Anything below 4V and you will go "out of regulation" ...


2

As soon as I connect up the battery, I loose the Serial Monitor connection (even though the USB cable is still connected). So I can no longer see what's going on inside the Arduino for debugging purposes. Why? How can I continue to see the Serial Monitor? Is there a way to see the serial output from somewhere other than the USB jack? Probably because ...


2

You can use a common ground in fact it's the normal thing to do with external circuits such as relays, servos etc


2

What is the CONT button potentially used for? That's the trigger. Connect that to (-) and a disc should fire. What is the EXT potentially used for? I just tried guessing by putting the 9V power supply into the CONT and EXT buttons by using a breadboard, nothing happened from this, That is for triggering another device when this triggers. With your pop ...


2

Wiring 6 batteries up so it gives you both a stack of 3 and a stack of 4 is not easy, and although you can do it you shouldn't do it. The only arrangement is this: simulate this circuit – Schematic created using CircuitLab (The grey link is optional and makes little difference if it's there or not). The reason you shouldn't really do that arrangement ...


2

Your idea is sound, but your implementation is flawed. First, you don't want to bother with "wake" and things like that - when the chip gets power it just starts from scratch - that's your "wake" signal. Your code will just be "Hold it on" and "Make a sound" followed by "Let it switch off". You only need one ...


2

The L293D has about a 2.6V drop on the output pins. That means for a 3V motor you need to provide about 5.6v for it to run at full speed. 5V will work, but it will run slightly slow and underpowered. 9V batteries are useless. Only any good for very low power applications like smoke alarms. They just can't provide the current you need. Instead you need to be ...


1

You could also use a 4 channel relay for making the motors work and they can be independent of using power from arduino and is really effective, I sometimes use it for high voltage optocoupling and can be used for small ones too all you need to do is build logic and everything would work fine I assume you know how to reverse polarity on a dc motor. Relays ...


1

The way you have it set up is fine if you aren't going to light up all the LEDs at full brightness. And if you do, you're not going to break your ESP32 Dev Board the way you have it set up in your diagram (since you are not running the power THROUGH the board). The LiPo battery probably has its own little regulator on it to prevent it from being damaged. ...


1

Everything was correct and my circuit is also good. The only difference i found is to this below line: temp = (analogvalue * 3.3) / 1024.0; Which should be temp = (analogvalue * 1.0) / 1024.0; We are multiplying because we are referencing the voltage from voltage divider circuit as 1 volt. After doing this, i am getting the exact values battery voltage ...


1

Since it is a freezer (operating temperature unknown) I am assuming it is connected to the mains why not do the same with the electronics. This will save you a lot work and time and when you find out it will not work in a Faraday cage as stated by timemage. Leave the sensor wire long enough to mount the electronics outside just in case. Also consider ...


1

I think all this effort is unnecessary. The ATTINY45 pulls a maximum of 2uA when sleeping... ..and in practice I've found the typical current to be much less. If, say, you are using AAA batteries for you project then you could sleep for more than 100 years. In practice your batteries will self discharge long before this, so any potential power savings by ...


1

If you connect the AtTiny chips in parallel, they will all receive the full voltage from your battery. If you exceed the current output of your battery the voltage will droop. If the AtTiny chips need 3.5V and you give them 6V instead, it will likely destroy the chips. The short answer: Don't try to drive microcontrollers directly from batteries. You should ...


1

you can use a breadboard and jumper cable. connect the VCC and GND of battery to a breadboard, do this for your Arduino and sim card module too. just remember they should be in a one row. GND with GND row, and VCC with VCC row note: this way is okay just for debugging


1

My Nano clone appears to be the same make as yours. Certainly the underside of it looks identical. On my clone, and I believe yours, the TX LED is wired as follows 5V -- RESISTOR -- LED -- TXD/D1 The 5V node is just the 5V pin which is fed by USB bus voltage via a diode or by the output of the AMS1117 voltage regulator. The TTL level serial TX signal ...


1

Although your solution would work, it seems open to problems such as missed clicks, starting at a different place etc. A better, more robust and error free solution might be to use a hall sensor. Essentially what a hall sensor does is close a switch when a megnetic force is applied. So all you have to do is add a magnet to your conveyor/chain. This way, you ...


1

You need to connect (-) to both the battery - terminal and to the Arduino ground. Connect CONT to a digital output pin on the Arudino. When you set the Arudino pin to LOW, it should trigger the disc launcher. If the disc launcher uses CMOS logic you should be good to go. IF it uses TTL logic then you will need a TTL driver chip or a transistor or you might ...


1

No. Absolutely not. A LiFePO4 battery is 4.2V when fully charged. The absolute maximum voltage of an ESP32 is 3.6V. You will kill the ESP32. Instead you need to have a voltage regulator with a very low dropout. Ideally a switching ("buck") regulator with a zero-dropout "pass" mode to give the maximum life from your battery. Even better is ...


1

Simple: duty = (3.2 / vcc) * 255;


1

Check your battery, it is behaving like a rechargeable one without a charger. Mine have the letter "R" at the end of the part number. There are a lot of RTC modules that charge the battery. Conversely they are some that do not charge the battery. Are you powering it with something other then the coin cell.


1

Use a buck/boost voltage regulator. Those are high efficiency switching regulators, and can either increase or decrease the input voltage. Feed the output of the regulator directly into the Arudino's 5V (or 3.3V) line, bypassing the on-board voltage regulator. What input voltages do the 2 devices need? Both 5V? If so, you can use a single voltage regulator ...


1

Consider using a 12V sealed cell lead-acid battery. Those are fairly cheap and easy to find in a wide variety of capacities, and chargers are also simple and easy to find. A car battery would power your system approximately forever, since they have such huge capacity. Figuring out how long a given type of battery will last is a simple question of math. ...


1

I think you should go with 3 lithium batteries in series and for proper balance charging of batteries, you can use an off the shell 3s lithium charging circuit like this here.So you will get 4.2*3 = 12.6V on full charge and on full discharge you will get 3.7*3=11.1v out of the battery. So still I think your pump motor would work on 11v and ther are chances ...


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