Help me with setting up a transistor switch

Status
Not open for further replies.
S

sz

Newbie level 4
Joined
Mar 28, 2005
Messages
6
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,334
I am using simple transistor switch(to turn on Relay) on 2n2222 that turn On when +5V on Base and turn Off when 0...-5V on Base

How can I make it so that when +5V on Base it turns Relay On and then it stays always on even when voltage on Base drop 0...-5V

Of coarse I can use additional Relay but is it possible to make it without additional relay?
 

Re: transistor switch

One option is that you could use a double pole relay and use the other switch to permanently turn on the relay by bypassing the transistor.
Another option is to use a SCR, by connecting the gate to transistor emitter(assuming you are using a npn transistor) and grounding the cathode and connecting the anode to the relay terminal which was previously connected to the collector. Also use a pull down resistor to the emitter.

Hope this helped.
 

    S

    sz

    Points: 2
    Helpful Answer Positive Rating
Re: transistor switch

Thanks. What SCR would you recommend for Relay 5V 70mA
 

Re: transistor switch

Ypu can use for example a C106D1, a very well known SCR.
Another option is to use the SCR used on the Christmas Lights ( usually are 4 each ) but now I don't know the type.

Mandi
 

    S

    sz

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…