learning4knowledge
New Member
Hello all,
I'm new to electronics & building circuits, I'm finding it interesting.
For my first project Im making a switch (12v actuator) that opens when pressure exceeds a certain value. Im using a PIC 16f690 & everything is going good but I'm having issues with the Rb for the transistor (not switching on).
Im using a TO92-3, 12v, 3A NPN transistor ZTX688B with a hfe ranging from 500 to 100. my solenoid is 12v 500ma 24ohm. I'm currently using a 200ohm 1/2 watt as Rb but my transistor is not switching. Also, I have a 1N4007 in parallel with the solenoid.
When the 16F690 output is "on" I'm getting ~ 4v to the input of Rb & an output of ~
763mv which should be enough to switch the NPN on as the datasheet states Vbe on is max 1V.
Is there something that I maybe misundertanding? Are my values incorrect? Any help with this would be greatly appreciated. Remember I'm new to this so plain english will be needed![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Thanks
I'm new to electronics & building circuits, I'm finding it interesting.
For my first project Im making a switch (12v actuator) that opens when pressure exceeds a certain value. Im using a PIC 16f690 & everything is going good but I'm having issues with the Rb for the transistor (not switching on).
Im using a TO92-3, 12v, 3A NPN transistor ZTX688B with a hfe ranging from 500 to 100. my solenoid is 12v 500ma 24ohm. I'm currently using a 200ohm 1/2 watt as Rb but my transistor is not switching. Also, I have a 1N4007 in parallel with the solenoid.
When the 16F690 output is "on" I'm getting ~ 4v to the input of Rb & an output of ~
763mv which should be enough to switch the NPN on as the datasheet states Vbe on is max 1V.
Is there something that I maybe misundertanding? Are my values incorrect? Any help with this would be greatly appreciated. Remember I'm new to this so plain english will be needed
Thanks
Last edited: