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2n3904 Switch

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8 Threads found on 2n3904 Switch
I have two LDR's from solar garden lights. In daylight (not sunlight) they measure about 24k ohms which is not low enough to completely turn off the transistor, unless it is very cold (the circuit is also a thermometer). The datasheet for the 2n3904 shows that its current gain is barely enough to use a resistor as high as 100k in that circuit so e
Okay, got it. The Rds(on) of MOSFET should be lowest. But why the transistor need to be such big 2N3055 (10A)? Can't 2n3904 do the job?
I would say the 2n3904 its not on your list but if talking about it for the purpose of learn I'd go for something that is going to be cheap to replace if say it burns out.
Try using a NPN transistor such as the 2n3904 as the switch instead of the NMOS. The transistor is current controlled unlike the gate of the NMOS which is voltage controlled. Make sure to put a resistor on the base and a resistor in series with the LED.
I am using 2n3904 as a switch to switch ir leds from a 74 series ic. It works fine until about 3MHZ and i just need a faster transistor i think any suggestions here is the schematic
Hi sbl, You can make a one shot or monostable pulse with the 555. Power supply is 5VDC Pulse needs to be at least 8 clock periods wide. You then need to invert the output with a 2n3904 NPN transistor See "NPN Common Emitter switch here:
You might get more help with: a) a better subject heading b) a better place to show the picture - you can upload it here so everyone can see it! Anyway, 1.8 ohms on 9V will be 5 amps. The poor old 2n3904 would go up in smoke if you put 5A through it, but you cannot with a 2k ohm base drive to 5V - the transistor doesn't have enough curren
Hello, Sorry if this topic is posted in the wrong forum. I've got the following. To switch a load with a microcontroller i use a 2n3904 transistor. The collector of this transistor is connected with a 2k2 resistor to +24V. The base of the transistor is connected with a 22k resistor to a output of the microcontroller. The emmiter of this transi