555 servo control gets hot

Discussion in 'General Electronics Chat' started by CTRL+X, Apr 4, 2015.

  1. CTRL+X

    Thread Starter Member

    Jul 1, 2009
    So I am using this circuit to run a servo, the the pontentimeter replaced by an LDR. Trying to use it to control window blinds. Open when light, close when dark, ect...

    It seems to work fine, however the 555 chip gets too hot to touch very quickly.
    I ran it for about an hour, but not sure how long it will last being that hot.
    Any way to modify this circuit to mitigate the heat, or suggestions on a different circuit? I've seen people using an Arduino, but I don't currently have one.
  2. OBW0549

    Well-Known Member

    Mar 2, 2015
    If you wired it up as shown and with the component values given, it shouldn't get hot at all. Check your wiring.
  3. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
    I concur with OBW0549

    Please double-check the circuit with special attention to R2, R3 and the power supply...
    Good luck and best regards:)
    Last edited: Apr 4, 2015
  4. MaxHeadRoom


    Jul 18, 2013
  5. CTRL+X

    Thread Starter Member

    Jul 1, 2009
    Yep, that was it.... lol. I had an 82 ohm on R1 instead of 820, and somehow had completely overlooked R2. Corrected these, and it is no longer heating up, and seems to be functioning ok.
    It does seem to get a bit of chatter when the light intensity is changed quickly, however if it is facing out a window, it shouldn't have that issue.
    I'll also look into that other circuit as well.