1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

[Help] 555 IC Keeps Blowing Up

Discussion in 'General Electronics Chat' started by Vimal Raj, May 20, 2017.

Tags:
  1. Vimal Raj

    Vimal Raj New Member

    Joined:
    May 20, 2017
    Messages:
    15
    Likes:
    0
    Hi, I'm new to circuits and electronics stuff, so kindly help me to solve the issue.

    I'm trying to add led DRL to my car, everything is working well if I power my circuit with 9V battery, but if I connect it to car battery after 3-5 seconds it getting blown. I have no idea why it's happening, I have attached schematic for reference. Capture.jpg

    Thanks.
     
  2. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

    Joined:
    Apr 17, 2007
    Messages:
    7,247
    Likes:
    961
    Location:
    Loveland, CO USA
    Hopefully you have pins 1 and 8 connected up.
    Normally there is a capacitor across the supply. (0.1uF and maybe a large cap to)
    The absolute maximum voltage on the LM555 is 16.
    A car voltage is 12 (more or less) when stopped.
    BUT
    When operating the voltage is 14.5 volts. (could be as low as 12 or as high as 18)
    My guess is that the supply voltage is too high.
     
  3. chemelec

    chemelec Well-Known Member

    Joined:
    Apr 4, 2004
    Messages:
    2,116
    Likes:
    77
    Location:
    Hedley, B.C. Canada
    Does Pin 1 of the 555 go to battery Negative?
    You should also put a 100 Ohm Resistor Between the Pin 3 Output and the Base of the Transistor.
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. Vimal Raj

    Vimal Raj New Member

    Joined:
    May 20, 2017
    Messages:
    15
    Likes:
    0

    Ignition was off while testing out and I tested voltage of battery it was showing around 12.45. Doubt that leds draw more current despite having transistor.
     
  6. Vimal Raj

    Vimal Raj New Member

    Joined:
    May 20, 2017
    Messages:
    15
    Likes:
    0
    Yes, I connected both ground and supply, will try out adding resister between output and npn base.
     
  7. Vimal Raj

    Vimal Raj New Member

    Joined:
    May 20, 2017
    Messages:
    15
    Likes:
    0
    Adding resister (100 ohm) at output solved the issue.
     
  8. chemelec

    chemelec Well-Known Member

    Joined:
    Apr 4, 2004
    Messages:
    2,116
    Likes:
    77
    Location:
    Hedley, B.C. Canada
    What Transistor is that? A Power Type?

    And it would be better if your "LED's and Resistors part of the Circuit" was connected between the Battery and Collector.
    Not from the Emitter to Battery Negative.
     
  9. crutschow

    crutschow Well-Known Member Most Helpful Member

    Joined:
    Mar 14, 2008
    Messages:
    10,591
    Likes:
    477
    Location:
    L.A., USA Zulu -8
    ONLINE
    This LM555 data sheet from TI states the maximum is 18V.
    upload_2017-5-20_11-9-19.png
     
    Last edited: May 20, 2017
    • Agree Agree x 1
  10. alec_t

    alec_t Well-Known Member Most Helpful Member

    Joined:
    Jul 10, 2011
    Messages:
    9,242
    Likes:
    1,218
    Location:
    Cardiff, Wales
    In an auto environment there will be load-dump spikes well above 18V. Suppression components would be advisable.
     
    • Like Like x 1
  11. Vimal Raj

    Vimal Raj New Member

    Joined:
    May 20, 2017
    Messages:
    15
    Likes:
    0
    I'm using 13005A, and after connecting leds in collector part, I can see the increase in power slightly. Technically emitter should produce more power with collective of base and collector but why it's other way round?
     
  12. chemelec

    chemelec Well-Known Member

    Joined:
    Apr 4, 2004
    Messages:
    2,116
    Likes:
    77
    Location:
    Hedley, B.C. Canada
    In the Emitter, It changes the Base Bias and effectiveness to fully turn on.
     
  13. Vimal Raj

    Vimal Raj New Member

    Joined:
    May 20, 2017
    Messages:
    15
    Likes:
    0
    Okay, I'll remember this in my future works, thanks.
     
  14. chemelec

    chemelec Well-Known Member

    Joined:
    Apr 4, 2004
    Messages:
    2,116
    Likes:
    77
    Location:
    Hedley, B.C. Canada
    If you Need to have the LED's to Battery Negative, than you should use a PNP Transistor.
    Emitter to Supply and LED's go Collector to Battery Negative
     
  15. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

    Joined:
    Apr 17, 2007
    Messages:
    7,247
    Likes:
    961
    Location:
    Loveland, CO USA
  16. chemelec

    chemelec Well-Known Member

    Joined:
    Apr 4, 2004
    Messages:
    2,116
    Likes:
    77
    Location:
    Hedley, B.C. Canada
    Texas Instruments, NE555 and SE555, are rated to 18 Volt
     
  17. crutschow

    crutschow Well-Known Member Most Helpful Member

    Joined:
    Mar 14, 2008
    Messages:
    10,591
    Likes:
    477
    Location:
    L.A., USA Zulu -8
    ONLINE
    I see no problem with using an NPN emitter follower in this application.
    The LEDs already need a resistor to control the current, so if the lower voltage from the emitter follower is a problem, you just need to reduce the resistor values to compensate.
     
  18. chemelec

    chemelec Well-Known Member

    Joined:
    Apr 4, 2004
    Messages:
    2,116
    Likes:
    77
    Location:
    Hedley, B.C. Canada
    Yes you can do that, But not the best way.
    Probably not a Problem but it adds a bit of heating to the transistor.
     
  19. Vimal Raj

    Vimal Raj New Member

    Joined:
    May 20, 2017
    Messages:
    15
    Likes:
    0
    Either case I don't get as much brightness as I connect it to battery directly, may be I should try darlington to get more gain.
     
  20. chemelec

    chemelec Well-Known Member

    Joined:
    Apr 4, 2004
    Messages:
    2,116
    Likes:
    77
    Location:
    Hedley, B.C. Canada
    Better Yet, Use a Power Mosfet.

    Transistors have a 0.6 Volt Drop, Collector to Emitter.
    Corrected: Mosfets have a Low Resistance between the Drain to Source.
     
    Last edited: May 21, 2017
  21. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

    Joined:
    Apr 17, 2007
    Messages:
    7,247
    Likes:
    961
    Location:
    Loveland, CO USA
    1) Don't use a MOSFET as a emitter follower (source follower) like in the schematic.
    2) Transistors can have very low C-E voltage drop. It is common for the C-E voltage to be less than 0.6V. Maybe you are thinking about B-E voltage.
    3) MOSFETs have high resistance Gate to Drain or Gate to Source. Maybe you are thinking about the resistance of D-S.
     

Share This Page