- #1
No output from 7905 when in increased current
In summary, the user is having issues with the LM7905 negative voltage regulator when configured in high current mode and parallel transistor short circuit protection. They have provided a circuit diagram and mentioned that the load connected to the output is 100 ohm (50mA). Upon further inspection, it is noted that the circuit has several errors and the user has made some corrections. They also mention that the 7905 was damaged but has since been replaced and initial tests show that the circuit is now working. The user plans to provide updates on the project in the future.
- #2
berkeman
Mentor
- 67,951
- 21,413
ElectroPhysics said:
The LM7905 is a negative voltage regulator. So Q1 is backwards, and your polar capacitors are upside-down. You should also show the ground connection on the 7905.
- #3
berkeman
Mentor
- 67,951
- 21,413
Actually, a bunch of stuff looks wrong in that circuit. Where did you get it?
- #4
- #5
berkeman
Mentor
- 67,951
- 21,413
ElectroPhysics said:
If you hook it up as just a plain 3-terminal regulator without the extra dropping transistor, does it work?
- #6
ElectroPhysics
- 115
- 2
berkeman said:
the project is in freeze stage as soon as i finish it i will let forum know about the results.
- #7
ElectroPhysics
- 115
- 2
7905 was damaged! i replaced it and initial test shows the circuit is working.
FAQ: No output from 7905 when in increased current
1. What is the cause of no output from 7905 when in increased current?
The most common cause for this issue is a short circuit in the circuit connected to the 7905. This can result in the 7905 being overloaded, preventing it from supplying any output.
2. How can I fix the issue of no output from 7905 when in increased current?
To fix this issue, the short circuit in the circuit connected to the 7905 must be located and removed. Once the short circuit is eliminated, the 7905 should be able to supply output again.
3. Can a faulty 7905 be the cause of no output when in increased current?
Yes, a faulty or damaged 7905 can also result in no output when in increased current. It is important to check for any signs of damage on the 7905 and replace it if necessary.
4. Are there any other potential causes for no output from 7905 when in increased current?
In addition to a short circuit or faulty 7905, other potential causes for this issue could include incorrect voltage input, damaged components in the circuit, or incorrect wiring.
5. How can I prevent no output from 7905 when in increased current in the future?
To prevent this issue from occurring, it is important to carefully follow the specifications and instructions for using the 7905. This includes ensuring proper voltage input and avoiding overloading the 7905 by staying within its current limit.