(The IRL540 is rated at 20 Amps continuous). VGS = 4.0 V and a resulting Drain-Source resistance of 0.11Ω., but I am not planning to draw 20Amps through the circuit. 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. The maximum collector current of the 2N2222 is 800mA, whereas the bc547's is 100mA.īoth the 2N2222 and the BC547 have the same power dissipation (500mw), the 2N2222 has a DC gain of 75 to 300HFe and the BC547 has a DC gain of 110 to 800HFe, and the 2N2222 has a thermal resistance of 146k/w and the BC547 has a thermal resistance of 83.3 C/w.īecause the transition frequency of 2N2222 is 250MHz and that of BC547 is 300MHz, the noise figure on 2N2222 is 4db and on BC547 is 10db.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. The voltage between the emitter and the base is 5 volts in 2N2222 and 6 volts in BC547. The collector to base voltage at 2N2222 is 60 volts, whereas it is 50 volts at BC547, and the collector to emitter voltage is 30 volts at 2N2222 vs 45 volts at BC547. The 2N2222 has an emitter, base, and collector pinout, whereas the BC547 has a collector, base, and emitter pinout. The BC547 transistor came in a to-92 package, but 2N2222 transistors, such as the PN2222 and KN2222, also came in to-92 packages. The 2N transistors were packaged in a to-18 package, which means they were enclosed with metal. The 2N2222 transistor is more powerful than the BC547. Collector to Emitter Voltage (VCE) is 30V.Collector to Base voltage ( VCB ) is 50V.Collector to Emitter Voltage (VCE) is 45V.DC Current Gain range is 110 to 800 hFE.The maximum frequency on this frequency is 250MHZ, which is the 2N2222 transistor's transition frequency. The trigger terminal's maximum bias voltage is 200 mV, while the 2N2222 transistor's maximum bias current is 200 mA. The maximum collector current of the 2N2222 transistor is 800mA this is the greatest current that this device can handle. The maximum current gain of the 2N2222 transistor is 300hFE, and this number determines the transistor's amplification factor. A bipolar NPN transistor, the 2N2222 is a transistor with two poles.
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