tip35
Junior Member level 1
Hello ! I am working at a LM317 power supply (tracking preregulator) and I found on the internet a schematic for overload indicator, which I added into my simulation and into my test circuit. After simulating, I found that the Base current of Q9 has spikes of about 4.5-5A, which I think that is very high for a BC327. By adding a 100R (R26) resistor into Q9's base results into a lower value current. Please find below the schematic of the circuit and the simulation results (1st result is with R26=100R and 2nd with R26=0R).
Are any other modifications needed ?
Can R26 value be as high as 1k ?
Schematic:
![1640100562609.png 1640100562609.png](https://www.edaboard.com/data/attachments/103/103517-cedd09d9e333146569fac8e6fc916c31.jpg)
High current spikes from BC327 base:
![1640100627362.png 1640100627362.png](https://www.edaboard.com/data/attachments/103/103518-cdaaa7aed6d131eda656a6cc7643755e.jpg)
Adding 100R resistor in BC327 base:
![1640100683072.png 1640100683072.png](https://www.edaboard.com/data/attachments/103/103519-202b4f029133aa970343661d9cb3fa04.jpg)
Are any other modifications needed ?
Can R26 value be as high as 1k ?
Schematic:
![1640100562609.png 1640100562609.png](https://www.edaboard.com/data/attachments/103/103517-cedd09d9e333146569fac8e6fc916c31.jpg)
High current spikes from BC327 base:
![1640100627362.png 1640100627362.png](https://www.edaboard.com/data/attachments/103/103518-cdaaa7aed6d131eda656a6cc7643755e.jpg)
Adding 100R resistor in BC327 base:
![1640100683072.png 1640100683072.png](https://www.edaboard.com/data/attachments/103/103519-202b4f029133aa970343661d9cb3fa04.jpg)