#2n2222 transistor switch circuit how to#

But if you are not planning on stressing the part (higher voltages, etc) both will work well, especially for simple switching and logic circuits. The 2n2222A is a slight bit better in terms of Vceo, Vcbo, Vebo. What is the difference between 2N2222 and 2N2222A? Secondly, gain and leakage characteristics, PN2222A is properly a repackaging of 2N2222A, a better version of 2N2222. Firstly, package, PN2222 is in a molded-epoxy TO-92 2N2222 is in a TO-18 metal can. But there are subtle differences between them. The maximum amount of current that could flow through the Collector pin is 800mA, hence we cannot connect loads that consume more than 800mA using this transistor.įor most purposes, they are interchangeable. It is used as an amplifier to amplify voltage, current & power.ĢN2222 has a gain value of 110 to 800, this value determines the amplification capacity of the transistor. These transistors are used in Motor drive circuits like VFD or variable frequency drives. It is typically used in automation & embedded projects. In which device 2N2222 transistor is used?

The 2N2222 has a combined rise-time, fall-time, and storage-time of 310ns, thus the maximum switching frequency is about 3MHz so it's not appropriate for this application. It was originally made in the TO-18 metal can as shown in the picture. It is designed for low to medium current, low power, medium voltage, and can operate at moderately high speeds. The 2N2222 is a common NPN bipolar junction transistor (BJT) used for general purpose low-power amplifying or switching applications. It has three terminals named as: Emitter. It's a Bipolar junction transistor abbreviated as BJT. It is designed for high-speed switching applications at collector currents up to 500 MA and features useful current gain over a wide range of collector current, low leakage currents, and low saturation voltages.ĢN2222 is an NPN transistor, which means it has a single P doped layer embedded between two N doped layers. You can download the datasheet of 2N2222 from the link given below:ĢN2222 FAQ What are 2N2222 High-Speed Switches ?ĢN2222 is a silicon planar epitaxial NPN transistor in Jedec TO-18 metal cases. * Pulsed : pulse duration = 300 µs, duty cycle = 1 %. (T amb = 25 ☌ unless otherwise specified) SymbolĬolllector-base Breakdown Voltage (I E = 0)Ĭollector-emitter Breakdown Voltage (IB = 0)Įmittter-base Breakdown Voltage (I C = 0) They are designed for high-speed switching applications at collector currents up to 500 mA, and feature useful current gain over a wide range of collector current, low leakage currents and low saturation voltages.ĢN2218/2N2219 approved to CECC 50002-100, 2N2221/2N2222 approved to CECC 50002-101 available on request.

#2n2222 transistor switch circuit how to#

If anyone has any ideas on how to get this to work or if they notice something I've wired backwards (highly embarrassing) please let me know.The 2N2218, 2N2219, 2N2221 and 2N2222 are silicon planar epitaxial NPN transistors in Jedec TO-39 (for 2N2218 and 2N2219) and in Jedec TO-18 (for 2N2221 and 2N2222) metal cases.

Thought the relay might be fried, swapped it out for a different one then connected it directly to 12V.

Thought I might be losing my mind and had wired the transistor in backwards.

I tried all of the above with a 330 ohm resistor instead of a 1k (R1) to increase the current through the transistor, no luck there either.

I thought maybe for some crazy reason 3.3V just wasn't cutting it so I tried a 5V signal instead, no luck there either.

I thought maybe the 2N2222 (TR1) base wasn't draining properly so I tried connecting it to ground via a 10k ohm resistor as well as the 1k ohm, no luck there.

I've tested all of the voltages and they're fine.

The only way I can get the relay to turn off again is to disconnect the 12V power source. When I push the tactile pushbutton the relay turns on, when I let the button go, the relay stays on. In reality the 3.3V signal will come from an ESP8266 but on my breadboard setup its coming from a power supply. I have a very standard NPN low side switch setup to turn a relay on/off from a 3.3V signal. I've been pulling my hair out over this for weeks and I can not for love nor money work out why it's not working.