Hi All
I'm new to Arduino as wanted a hobby after retirement to keep brain working. I have decided to make a useless box for my grandson as a first project. The main useless box program runs when connected to the USB. I have made a very simple servo program to move the servos while making the box for test runs/line up, running on a UNO R3. This is when i discovered the simple program works when connected to the laptop USB, but not when to the jack supply only, as this is how I wanted to run the box.
I have read on some forums that there can be an issue with the RX getting "hung up " when running through the jack and to ground the RX pin through a 10K resistor. I've tried that as well but still the same happens as above. Works OK on USB for main useless box program and simple program but not off jack.
I would like to run through the jack plug, as this takes away batteries and thought it would be easier to run off a 5V transformer plug and don't want grandson getting fingers in it. As i understand it is also protected using the jack for polarity, but not using VIN.
Please would you dumb down the answers, as I'm new to the electronics/Arduino scene.
Note that an Arduino is not a power supply. Which servos are you using? How many?
The difference in powering with USB and powering via barrel/Vin is that the voltage in the barrel/Vin goes through a voltage regulator to convert a voltage >= 7V to 5V. With virtually no heatsink, that voltage regulator will overheat and shut off if you draw too much current; a higher input voltage (e.g. 12V) will make the situation worse than a 7V input voltage.
Hi
Thank you all for replying so quickly. I will answer posts all together. Hope this is ok.
The voltage to the jack is 8V. The Arduino steps this down to 5V when I check at servos.
There are 2 x MG995 servos. Current approx 10mA each according to the spec.
I'm connecting the servos via 5V pin from the Arduino.
I have no LED connected yet, was going to look at this but when servos etc all lined up.
The simple program has no "while" coding, it is just enough to move the servo back and forth by manually inputting the degrees required.
Stupid question, but, Is the VIN and barrel the same source then ? they both do the same thing. I thought the barrel was safer due to the polarity protection.
When I see diagrams for batteries, they feed into the VIN. Can i just hard wire the power supply from a 5V transformer plug into the VIN. What are the consequences??
Thank you all once again for taking the time to help.
Then you should read the start of the forums instructions on , how to post, code, drawings, etc as much as you can as people here have no idea what you have in front of you.
2112
The power supply is a "connect it" multi adaptor with various Volt outputs, max 300mA 3.6VA(max).
Thanks for the warning about the regulator.
OK so as i understand it, use 5V regulator through the jack to power the Arduino, then a separate 5v supply to power the servos.
I'm still confused as to why when I connect from the laptop to the Arduino via the upload cable, everything works fine, even without a separate power source for the servos. Again this may be obvious but I'm missing it.
bluejets
Thank you for the prompt, but I have looked for this previous and not found where this is. I have found the About, FAQ, terms of service, Privacy and couldn't see the type of content you described . I'm obviously missing something simple again, so apologies. Where is this info please?
Thank you again for taking your time to read and inform me of my mistakes.
An Arduino is intended to control things, not power them. A few LEDs are fine, anything more is asking for trouble.
Servos generally pull too much current for an Arduino to source. Sadly, there are many examples online that contradict this and you can get away with it with USB power and one or two small, lightly loaded servos.
From memory, an Uno can provide ~150mA through the power jack and 500mA using USB power (e.g. from the laptop). You can use a USB charger - most of us have them littering the house as e-waste that came with our previous phones. Try this first.
Best though is to run the servos with a more powerful supply.
sterretje
Thanks for the heads up I did not take that in (reply5). I think then that the USB feed from the laptop does not go through the regulator, therefore being able to give enough power to the servos, however bad practice this may be, Thanks wildbill. So when I use the jack, the regulators will not allow enough power to the servos, therefore the need for separate power supply.
Eventually I get what you have been saying.
wildbill
Thank you for explanation and the advice, will have a try.
Thank you everyone for your patience with me on this.
bluejets
Found the advice section you informed me of. Apologies it would have helped everyone.
I wasn't lying that I needed it dumb down. You probably didn't realise how dumb it had to be haha.