Hot answers tagged

8

Transistors are solid state switchers, that is, they don't have any moving parts. MOSFETS are like transistors, but are rated for higher voltages. Relays are more expensive, but they have moving parts. Transistors and MOSFETS produce a lot of heat. They have 3 pins (usually) called the base, emitter, and collector. More info here Relays use a magnet to ...


5

For 100 LEDs in parallel you will also need 100 resistors, and a transistor (MOSFET) that can handle the total current for all the LEDs. For instance, at 20mA drive current you would be dealing with 2A - you'd need a (minimum) 2A power supply and a MOSFET that can handle 2A. Or you can think a little differently. If you use a higher voltage power supply ...


5

From your schematics it looks like: you connected the power supply backwards (on both schematics actually, I wonder how come you did not fry your Arduino) the external supply and the Arduino do not share a common ground as they should. Edit: about the orientation of the power supply: the (−) side of the supply (and GND of the Arduino) should be connected ...


4

In principle, I don't see any problems. Your heating pad uses 12V and 10W, which means it would be consuming slightly less than one amp of current. The MOSFET you linked can go up to 5A (needing a heat sink with over 1A). You could use PWM (there are 6 pins on a Uno that can do that) to provide pulse-width modulation to control the amount of output you give ...


3

Try adding a delay into your loop. In your code pin 13 will toggle very rapidly, much too fast to see it. For example: void loop() { digitalWrite(13,HIGH); delay (1000); digitalWrite(13,LOW); delay (1000); } It doesn't look wired correctly. For an N-channel MOSFET the Source should go to ground, like this:


3

T1 and T2 implement a power supply ORing of the VUSB and VIN voltages. Read this for extended information. The body diode of each MOSFET performs the basic ORing function. When the MOSFET is turned OFF it just behaves as a diode. But when the MOSFET is turned ON, the diode is shorted by the conduction channel, thus avoiding its voltage drop (and achieving a ...


3

It all depends on how the circuit works and how it is controlled. A basic H-bridge looks like this: Normally you have one MOSFET from each side turned on and one turned off - so for example Q1 and Q4 on to make the motor turn one way, or Q2 and Q3 to make it turn the other. Turning on Q2 and Q4 for example would make the motor "brake". However, if it is ...


3

Big differences between relays and transistors are: relays are all-or-nothing (like switches) whereas transistors can transmit more or less current through the collector based on the current present on their base. relays provide isolation between the command circuit (the one with the electromagnet) and the controlled circuit (the one on the switch side of ...


3

You can use a RFP30N06LE mosfet. It can support up to 60V 30A Here is a wiring schema


3

Absolutely not. Not under any circumstances. Dimming AC is a considerably harder task, and doing it with 220VAC can be deadly. To do it you need: A zero-crossing detection circuit A TRIAC driver circuit A suitable TRIAC to do the switching Software that will use the zero crossing information to time the switch-on of the TRIAC to a certain point in the ...


3

You should be using a P-channel MOSFET (which is set to be normally OFF with a pull-up resistor) and the Arduino is responsible for keeping it on: simulate this circuit – Schematic created using CircuitLab In this schematic M1 is normally off. You press and hold SW1 and the Arduino gets power. The first thing it then does is turn on the GPIO. That ...


3

First of all, the LM317 and the are FDC855N different types of devices. The LM317 is a voltage regulator whereas the FDC855N is a discrete MOSFET. A MOSFET will act as a fast switch allowing you to control the LED's brightness using Pulse Width Modulation. For what you're trying to do, you can think of the MOSFET as a voltage-controlled switch. If the ...


3

You have an N-channel MOSFET. That is not suitable for switching the 12V supply of an Arduino. Instead you need a P-channel MOSFET which has the gate pulled up to 12V using a resistor, and then an N-channel logic level MOSFET which is used by the Arduino to pull the gate of the P-channel MOSFET LOW to turn it on. Something like: simulate this circuit &...


2

You can make your own. Buy a protoshield and 4 fets (and a few resistors). You can also use the shield you linked to, by not using the + terminals on the board. Just connect the + of the lights directly to the battery and only the - of the light to the shield. The Uno can be powered by up-to 20V, so you can connect it directly to the battery.


2

The LED strip with blue ones requires a higher current drive. Arduino output pins can drive only 20mA max(ideal). Try an external power source.


2

For the mosfet circuit. Are you using an external power supply? The reason why you cannot mix any color might be due to the fact that you're not providing enough current to the led strip, so it just work fine when turning on each channel individually. Check the current the led strip draws (which usually is provided as amp per channel per meter) and use a ...


2

In your existing arrangement. Swap to P Channel FET Swap drain and source leads (right hand two). This will work for up to 5V feed to LEDs. To get 12v operation you will need to add a driver between the FET gate and the Arduino. see circuit diagram below. To operate with FET on the HIGH (V+) side when V+ is greater than the rduino's supply voltage, ...


2

Summary: It looks as though you can just drive BL directly with the PWM-output. What happens when you do? Details: (1) As shown, even if the circuit did what you wanted, all you would be doing is providing a rail to rail (0V to 3.3V ) signal to the BL pin. You can do this by connecting PWM-out to BL directly. Does this work? If the LCD and Arduino used ...


2

By my calculations you are sinking 6 amps: 72 W / 12 V = 6 A I have some doubt that the Arduino board is designed to handle that amount of current through its ground plane. Try running a separate ground wire to the MOSFET sources. I would also be concerned about the gauge of wire you are using, and whether the prototyping board can handle that amount of ...


2

You can use a 5V Solid-State Relay module to control light bulbs. They cost $4-6 from US-based suppliers and $1-3 from a Chinese supplier. Just hook up the supply to the center pin and the load to either the NO or NC pin. Supply 5V to the module and wire a digital pin to the module to control it.


2

Yes, according to the datasheet (which should always be your first port of call for any chip) the outputs are Open Drain. That means you require a pullup resistor, exactly as if the outputs were simple buttons.


2

You have a timer conflict. Pin 9 is OC1A which is the Output Compare Channel A pin of Timer 1. However the Servo.h library also uses timer 1. So you can't use servos and still use pins 9 (OC1A) and 10 (OC1B) as PWM. However, you can still use pins 3, 5, 6 and 11 as PWM since they are on other timers.


2

It's known as a "zero drop-out diode". When the power is first applied the body diode of the MOSFET conducts and powers the system. That imposes a (roughly) 0.7V drop on the input voltage. Once the power gets through the regulator and is regulated to 5V that is then fed back into the gate of the MOSFET, which turns it on (as long as -5V is above the source ...


2

Switching power on and off to hard drives is not as simple as you may think. First you have three voltages to control - 3.3V, 5V and 12V, and on top of that you have (ideally) pre-charging for the 5V and 12V pins. The power-on sequence would ideally be: Power up 5V and 12V pre-charge Power up 3.3V, 5V and 12V main power That's 5 poles for one drive (...


2

generic DC connector advice: avoid the use of connectors which connect serially, like headphone jacks. you make strange combinations while plugging in avoid connectors which do not latch, like headphone jacks in a system like yours, with stages and signal processing in between, use different connectors for each phase, so you can not get it wrong use ...


2

No, it won't: The diode D1 is backwards. The opto-coupler is wired completely wrong. You don't actually need the opto-coupler as long as the threshold voltage of the MOSFET is low enough for the Arduino to switch. However if you do want (or need) to use it you should wire it like this: simulate this circuit – Schematic created using CircuitLab R1 ...


2

That's not a good choice of MOSFET I'm afraid. The on resistance is quoted as 14Ω when the gate is at -10V - however, you are only able to get -5V, so it will be considerably worse. That massive on resistance will be causing a massive voltage drop, which is what you are experiencing. You should find a MOSFET with an on resistance that is in the milli-ohm ...


2

I'll try to answer your post with "just words" and we will see how it goes. If it is not clear to you, i will post small schematic. I do not recommend the first schematic that you posted. You will likely reverse bias the BE (base emitter) junction with 12v. Most bipolar transistors have a maximum reverse BE bias of 5 v. I do recommend using bipolar so that ...


2

That little blue wire on your breadboard is shorting out the motor. You have most likely now blown the transistor and maybe your power supply. The 12V may also now have made its way into the Arduino through the dead transistor and nuked the rest of it. Alternatively, the massive base currents imposed by the shorted ground connection may have burned out ...


Only top voted, non community-wiki answers of a minimum length are eligible