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Regulating voltage made it worse???

Discussion in 'Troubleshooting and Repair' started by Hyteck9, Feb 14, 2020.

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  1. Hyteck9


    Feb 14, 2020

    I have a curious little project issue.
    I have a bluetooth board with relays on it.
    The hi power contacts on the relays do not get power from the board.
    For simplicity, I wired the hi power relay points to the same power src. It worked fine at first. About every 20th time a command was sent to the board, it would NOT fire the relay, even though the LED indicated the board recieved the instruction to do so for that specific relay. I would have to reboot it.
    I figured the draw from the relays ( which trigger solenoids.. a big draw ) was spiking the board somehow, so I introduced a resistor and zener diode regulator to keep things calm. The meter says it is working and voltage is good, but now firing a relay just once induces the problem. I have to turn it all off and back on before a relay will fire again. The relay power is being tapped at the same source, but upstream of the resistor and diode. That is it really, the only other wires go to a power toggle switch. Why does regulating voltage make it worse?
  2. davenn

    davenn Moderator

    Sep 5, 2009
    It wont unless you are doing something wrong

    Please show a schematic for your circuit ... else we are all just guessing
  3. Hyteck9


    Feb 14, 2020
    ok ! schematic_basic.png
  4. Bluejets


    Oct 5, 2014

    Attached Files:

  5. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Sir Hyteck9 . . . . .

    Now, before you have to goes out and spends enny of yer hard earned munneys . . . . .

    Try the addition of the two transient spike supresser diodes, now shown.
    Standard practice on the relay coil . . . . . . and your inductive value of solenoid may just be creating a multi hundred volt back EMF spike across the relay contacts JUST after they have opened 1/1000 ths of an inch . . . and it arcs across that gap into the supply line.
    Also consider a 100-1000 ufd electrolytic across the YELLOW X junction to ground . . . . to be sure that the controller module receives a stable voltage.

    RE- REFERENCING . . . . .

    73's de Edd . . . . .

    If you can think of a color that does not exist, is it being a pigment of your imagination?

  6. Hyteck9


    Feb 14, 2020
    Hello!! I have tried these and many other potential fixes this morning. No luck with those, but I think I did figure out the problem. When the solenoid fires, it seems to be disrupting the bluetooth radio reception. If I place the solenoid a tennis ball's distance from the controller, it fires repeatedly and consistantly. This sucks, because who wants a circuit footprint that big! Ha! So, how to shield the controller from the solenoid, without blocking the bluetooth radio reception at the same time!?!?
  7. bertus

    bertus Moderator

    Nov 8, 2019

    What shape is the solinoid?
    Perhaps a shielding around the solinoid might help.

  8. Tha fios agaibh

    Tha fios agaibh

    Aug 11, 2014
    I'm surprised it works at all with that zener regulator. The controller is limited to 15ma through the 300Ω resistor and most relays draw at least twice that.

    I would employ all the good suggestions given. Use a better more efficient regulator (lm7812 or switching type), use flyback diodes to mitigate spikes, add electrolytic cap to stabilize voltage and try shielding (nickel copper fabric or even a sheet of thin metal insulated with plastic).
    Martaine2005 and bertus like this.
  9. TomGeorge


    Sep 7, 2013
    Questions that should have been asked at the start of this tread.
    What are the specs of the solenoid?
    What are the specs of the relay?
    Have you got the solenoid wiring AWAY from the wiring to the Bluetooth?
    Make your power connections a star formation from the power supply, do not daisy chain your power supply wiring.
    What is your power supply? (specs)
    Sorry but for a decent thought out solution we need information about your project.
    davenn likes this.
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