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Grumpy Mike

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  • Motion Sensing Under Bed Lighting

    Sorry but there is an error with the circuit diagram. We had a member on the Arduino Forum who couldn't get this to work. This is because you have connected a 5V signal to the Vin of the Nano. This leads to a 5V regulator and as you (should) know a 5V regulator needs at least 6.5V to make it work correctly. So instead of what you put you need to connect your 5V regulated output to the 5V line of the Nano. The original circuit only worked by a fluke and it was on the very edge of it not working. A slight change in the actual voltage from your 5V regulated supply or a change in the type of PIR sensors will stop it working. When the Arduino member made this changes he got a fully working system. But for the sake of robustness everyone needs to make this change.

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  • Raspberry Pi Pico With I2C Oled Display and CircuitPython

    Step 1Once this code is run, once Thonny debug information shows on the OLED. How do you stop this?When the code is run for a second time you get an error message saying that the GP pin is in use. How do you stop this?

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  • Arduino Spectrum Analyzer on a 10x10 RGB LED-Matrix

    No, a connection from a speaker is not suitable as an input. This is because it is a differential signal, that is one lead goes positive while the other goes negative. Then they swap over with the positive going negative. It is these negative signals that will destroy your Nano input pins. To use a speaker you would need an audio transformer with a center tapped secondary biased at half rail, followed by a differential input operational amplifier.

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  • Cutting Plywood Parts on a Laser Cutter.  I Made It at Techshop

    This is insane. A 60 watt Epilog laser cutter is more than capable of cutting this thickness in a single pass. The fact that you need 4 & 8 passes shows how broken your Laser cutter was. Either the optics were very dirty or the tube was knackered. This article shows up on the first page of a search but it is deeply flawed.

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  • Arbitrary Wave Generator With the Raspberry Pi Pico

    Great software, thanks for posting this. Just a point on your D/A. You can not make an 8 bit D/A with 1% resistors. With 1% you only get 1 in 100 resolution, that is just under 7 bits. So in practice you have a 6 bit D/A with 2 bits of noise. You do not get what is known as monoticity, that is the property where for any digital input one bit more gives a higher or the same output. It unfortunately a little understood problem homemade D/A converters.

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  • Arduino Spectrum Analyzer on a 10x10 RGB LED-Matrix

    R2 and R3 are not pins in the Nano. They are resistors that are connected to pins. As it stands on the original diagram R3 is connected between the Aref and the A7 pin on the Nano, and R2 is connected between A7 and the audio input.

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  • 'OK to Wake' Clock for Your Toddler

    Nice idea but sadly your electronic skills do not match your other excellent skills. Please see:- https://forum.arduino.cc/index.php?topic=683749.ms...For what you have done wrong.

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  • Why have you no resistor in the base of the transistor? As you have it you are drawing too much current from the Arduino pin and it is being damaged. Eventually this pin will fail and will not work anymore. It will not instantly stop working but over time it will.

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  • You have no current limiting resistor in your LED. They havent been fitted on an Arduino since at least 2006. The resistor on the sensor is going to the wrong place, it should go to 5V not ground. It will never work the way you have drawn it.

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  • Why no decoupling capacitors on the shift registers? This makes it a bad project for people trying to replicate it.

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  • Grumpy Mike commented on chr's instructable LED Cube 8x8x8

    You use two PN2222As in parallel. Why? Do you not know that transistors simply do not share current, FETs yes but bipolar transistors like that one no. You can't have tested it properly.

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  • That input circuit is a mess and risks damaging your audio device and your Arduino. You have not understood what you have read on the Arduino page. R2 should be connected to ground not your audio input. Your audio input should be connected to A7 through a series capacitor. You should not connect anything to the Aref input and R3 should go straight to the 5V connector.

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  • Grumpy Mike commented on AndreasN29's instructable RFID Lockbox

    That is just the power but you are feeding the 5V SPI signals from the Arduino into a 3V3 system. Do you not understand the consiquences of this?

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  • Grumpy Mike commented on AndreasN29's instructable RFID Lockbox

    I can't see any level translators between the 5V Arduino system and the 3V3 RFID board. While this might work initially it will, in time, fry your RFID card.

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  • Great idea but sadly very poor electronics design. Why two processors when one would have done? Why have all the strips driven off the same pin, this reduces flexibility. The omission of the resistor and capacitor means you project will fail much sooner than it otherwise would.

    See https://forum.arduino.cc/index.php?topic=514957.0 for why.

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  • Grumpy Mike commented on noahw's instructable LEDs for Beginners

    You said at the start:- "Never done any work before with LEDs and don't know how to use them? Its ok, neither have I."So what makes you think it is OK to perpetuate the rubbish ideas here.You always need resistors with LEDs, period, no ifs & buts.If you try and wire LEDs in parallel without a resistor they will not share the current evenly and you will damage them.

    You said at the start:- "Never done any work before with LEDs and don't know how to use them? Its ok, neither have I."So what makes you think it is OK to perpetuate the myths you have here?You always need a way to control the current with LEDs, and the simplest way is a resistor. The no resistor circuits shown here uses the internal impedance of your battery to limit the current, if you use another type of battery you can start a fire or have an exploding LED. It is irresponsible of you not to point this out as it could be a danger.If you try and wire LEDs in parallel without a resistor for each LED, they will not share the current evenly and you will damage them. Look at your own picture and you can see they are not the same brightness.

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  • "in the UK you can have a still that makes up to 5L if you have a permit.":Well that is a way oversimplification. See the second post in this link:-http://ww.homedistiller.org/forum/viewtopic.php?f=...

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