Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

npn trigger

Status
Not open for further replies.

Gunz1159

New Member
Can someone say what kind of npn transistor would i use to trigger a ckt which has 9V power supply. For example with this i have attached a ckt in the right most part around 4 transistors are used what r they. Can u please say me the exact product. ? ? ? ?
 

Attachments

  • 9.gif
    9.gif
    11.7 KB · Views: 265
The circuit to the right is a very, very basic H bridge. Without knowing the motor current there is nothing else to say. If the motor is very small and draws maybe 100 mA then use 2N2222 or 2N3904 transistors. What exactly are you trying to do? Every time the OP Amp triggers the Flip Flop the motor will change direction.

Ron
 
As shown the Bipolar H bridge will not work. You cannot turn on the high side NPN's. Both Q and Q' will be limited to bottom Vbe diode.
 
what i'm trying to do is to trigger a relay using a npn transistor. A single relay, may be only one npn is required.

The whole project is about the mic to trigger relay using a whistle.
 
Last edited:
Whole different animal there. Just a single transistor is needed. The flip flop will toggle with each trigger from a whistle blow. Give this link a read paying attention to the base resistor and the use of a diode across the relay coil. Note, the transistor used needs to be able to handle the relay current. For safe operation the 2N2222 or 2N3904 I mentioned holds true at 100 mA for a comfortable margin.

Ron
 
hey can i use 2N5551 instead and a IN4007 ???????????????

The diode goes across the relay coil to suppress the inductive kick when the coil field collapses. The transistor is used to drive the relay and the transistor is chosen based on the relay coil voltage and current. Did you read the link I posted? It explains things as to selecting the transistor. The 1N part number is a diode and the 2N is an example of a transistor.

Ron
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top