This does reduce the data voltage at the gate slightly (it is a voltage divider) which is why some put the pulldown resistor on the other side of the gate resistor. My drawing, above, is what Toshiba recommends. There is some discussion where to put the gate resistor. It's value is not critical in low-speed switching. The gate-source resistor is to keep the gate below the turn on threshold when there is no input. But we generally aren't working in the MHz frequencies, so just about any resistor value will work for us. The value computation is dependent on the speed of switching you need. (The gate-source capacitance the problem here, but since we aren't likely to be working in the MHz switching frequencies, it can be generally ignored). The gate transistor is needed to reduce the inrush of current when the gate receives a logical high. (The IRL540 is rated at 20 Amps continuous). y del Consejo (UE) 2016/679, del 27 de abril de 2016, sobre la protección de las personas físicas en lo que respecta al tratamiento de datos personales y sobre la libre circulación de dichos datos y la. VGS = 4.0 V and a resulting Drain-Source resistance of 0.11Ω., but I am not planning to draw 20Amps through the circuit. CDIL 2N2222A Transistor: NPN bipolar 40V 0,8A 0,5/1,2W TO18 4dB - Producto disponible en Transfer Multisort Elektronik.
The IRL540 is better than the 2N7000 for higher loads. I use it to power loads of less than 50 mA. I use the 2N7000 with 3.3V logic and ignore the higher Drain-Source resistance (which limits it's current capacity). MarkT is correct, there are few logic level MOSFETS that work at 3.3V (gate), and most are surface mount. I would expect something more like 100 to 200 ohms (assuming the Wemos pins can handle the current). Without a diode in this position you'll simply instantly fry the transistor the first time it switches off due to the inductive kick-back - the diode tames this.Ī 2N2222 might or might not be able to handle the current of this relay, but note the base current needs to be at least 5% of the load current for it to switch fully - you need to find out the Wemos board's pin current handling ability to judge this.Ģ.1k resistor does sound rather high though, that's only 1.4mA from a 3.3V drive voltage (3.3V - 0.6V) / 2100 = 0.0014. You'll see an 1N4007 diode in that circuit. Secondly when switching a relay you must have a free-wheel diode across the relay coil, as in this tutorial: So you need to measure the resistance of the relay coil and figure out the current it needs (I = V/R). This means the coil will be powerful and take a lot of current - but I can't find any proper data for it. I am stupid.įirstly the RF6105-12V-C relay seems to be a high power contactor, switching 150A. The relay is controlling a 12v linear actuator. I want the relay to engage when the pin d1 goes high. The relay engages when I get 0v or ground going to the point that the "collector" is going to in the diagram. Did I wire them up correctly? Is my resistor too large/small? I assume the transistors went bad or I shorted them out when mounting it. I have confirmed that the relays are still good, but I can't get it to work with the transistors. I mounted the actuator and it stopped working. I was able to engage the linear actuator via 3.3v from wemos board - transistor - relay several times without any problems.
I had two of the transistors with a 2.1K resistor switching two separate relays and it worked. I didn't have any TIP120's on hand, so yesterday I thought I would try the 2n2222 to do the exact same thing.
I did this same exact thing on another project, but I used a TIP120 transistor with a 2.1K resistor and arduino uno to do the switching, and it is still in use now. I am trying to switch a rf6105-12v-c (what I am calling a relay?) with a 2n2222 transistor. \$3.3\:\text\$ can be estimated from a datasheet or from a simulation.I have read many threads about using transistors to switch relays of larger voltages on with microcontrollers, but most of them end without a solution, or I am not smart enough to understand the responses given.
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