Problem Using Bipolar Transistor as a Switch

  • Thread starter Thread starter lindhaw
  • Start date Start date
  • Tags Tags
    Switch Transistor
AI Thread Summary
The discussion centers on using a bipolar transistor to convert a 5V signal from an IR encoder to a 24V signal. The original poster is struggling with the implementation and is unsure if they are on the right track. Suggestions include using an open-collector configuration to achieve the voltage conversion effectively. The poster expresses a willingness to learn about open-collector stages after initially being unfamiliar with them. Overall, the conversation highlights the importance of understanding circuit configurations for proper voltage level shifting.
lindhaw
Messages
9
Reaction score
0
Im new here and I am currently working on a small IR encoder project. I have the encoder working great but now I need to use the 5vdc signal that comes from the encoder and make it 24vdc. I am currently trying to use a bipolar transistor but its not working. The basic diagram that I am going off of is attached along with the schematic of the optical encoder schematic. Am i way off track or am I missing something obvious.

BTW I am using 20k for R1 and 200K for R2 for the switch
 

Attachments

  • optical encoder.png
    optical encoder.png
    11.3 KB · Views: 464
  • transistor.png
    transistor.png
    736 bytes · Views: 471
Engineering news on Phys.org
lindhaw said:
Im new here and I am currently working on a small IR encoder project. I have the encoder working great but now I need to use the 5vdc signal that comes from the encoder and make it 24vdc. I am currently trying to use a bipolar transistor but its not working. The basic diagram that I am going off of is attached along with the schematic of the optical encoder schematic. Am i way off track or am I missing something obvious.

BTW I am using 20k for R1 and 200K for R2 for the switch

Welcome to the PF.

Can you run the first stage off of 24V? A 5V pullup stage will not shut off a 24V high-side switch stage...
 
If you can't run the first stage at 24V, use an open-collector stage to convert from 5V to 24V.
 
lindhaw said:
I don't think I can do that because I think it would just burn up the emitter and possibly the receiver. I've also been looking into this http://www.goldmine-elec-products.com/prodinfo.asp?number=G18694 but I've never used anything like that so I am not sure if the response time will be fast enough.

Your link is just a DC-DC converter to convert a 5V power supply to a 24V voltage source.

What you want is a way to convert a 5V logic signal to a 24V logic signal, correct?

The way to do that is with an open-collector BJT stage. Are you familiar with those yet?
 
Ya that's correct. I am not familiar with those yet. Is that something that I could make or is that something that I should just buy?
 
ok dumb question sorry I just looked it up and I think i can manage one of those. Thanks for the advice! Ill let you know how it goes!
 

Similar threads

Mosfet, Mesfet vs Bipolar transistors in RF circuits
Replies
28
Views
5K
How to properly use a TIP47G transistor as a switch for larger currents?
Replies
22
Views
2K
What Factors Determine the Best Transistor Type for a 12VDC Project?
Replies
21
Views
6K
I don't understand transistors in combinations .... Or maybe basics ....
2
Replies
68
Views
6K
"Switching Transistor" OFF Impedance
Replies
8
Views
1K
NPN transistor and how it operates....
Replies
11
Views
2K
Bipolar Junction Transistor and CPU
Replies
11
Views
4K
Improving Transistor Switching for High Voltage Protection Circuits
Replies
18
Views
9K
Computer Science Student Seeks Advice on Switches & Junctions
Replies
9
Views
2K
Why Do We Require Transistor Switches?
Replies
10
Views
4K

Hot Threads

Recent Insights

Back
Top