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Thread: piezo switch problem

  1. #1

    Default piezo switch problem

    Hi,I'm working on a custom canister dive light and I have an odd issue.I use Cree XHP 70 6v, piezotg from taskled, LD3 driver and 2s5p 18650 battery.1. I connected the led (XHP 70 6V) and the piezo latch circuit directly to the battery (2s5p lion) without the led driver. The measured currentwas around 6A. I could switch ON/OFF the light by pressing the piezo button without any problem.2. I connected the led to the battery with the led driver and without the piezo latch circuit. I could "switch" ON/OFF and change modes by breaking and reset the connection between the driver and the battery.3. If the driver and the piezo latch are togethet in the circuit I can switch ON/OFF only at lower modes. If the led runs in 100% mode it is not possible to switch OFF. It also does not matter if there are other modes in the group or 100% is a single mode in a group, the phenomena is the same.Has anyone experienced similar things with piezo switches?

  2. #2
    Flashaholic
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    Default Re: piezo switch problem

    First I would check if this is a problem with Piezo. Take it out and just touch wires together to switch, see if issue persist.
    Either way you may contact George (from TaskLed) and ask about it because if issue persists then it looks like problem with piezotg board.
    If it goes away then it also may be an issue with piezotg, no idea maybe when pressed at high load it is trying to push more current thru piezo than it allows, shouldn't but something strange here!?

    If it works without piezo just touching wires try to put small capacitor between piezo legs, like few nF ceramic. Maybe is bouncing.
    Last edited by arek98; 03-22-2017 at 09:10 PM.

  3. #3

    Default Re: piezo switch problem

    I replaced the piezo button by a simple momentary switch. The problem remained the same.

    According to the description a NO switch is necessary but I thing I used NC. I have to double check it.

    The piezotg is rated up to 15 amps, xhp70 runs on 5-6 amp only.

    I have already contacted George, and he suggested to do some scope measurements, but it has not been done yet.

  4. #4
    Flashaholic* lucca brassi's Avatar
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    Default Re: piezo switch problem

    any progress on solution ? What is your piezo code ?

  5. #5

    Default Re: piezo switch problem

    Unfortunately no progress on solution at all.
    I use this piezo switch: https://www.aliexpress.com/item/ELEW...848486705.html
    Piezo latch: http://www.taskled.com/techpiezotg.shtml
    LED driver: https://www.dropbox.com/s/4utteoho2x...inary.pdf?dl=0

  6. #6
    Flashaholic* lucca brassi's Avatar
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    Default Re: piezo switch problem

    I could not find any useful data about that switch . It could be very sensitive ( operative force ? ) momentary or prolonged?

    On piezo crystal could be some electric charge that holds latching circuit on.

    Remember crystal microphones are build and work almost in same way .

  7. #7

    Default Re: piezo switch problem

    It is a momentary switch.
    The piezotg board was wrong. I have replaced it by another one and it works.
    George from taskled suggested to replace some capacitors, it might solve the issue with the previous board, but I have not done it yet.

  8. #8
    Flashaholic* lucca brassi's Avatar
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    Default Re: piezo switch problem

    I 'am glad that you managed to solve switch the problem. How are you satisfied with chinese piezo button in general?

  9. #9

    Default Re: piezo switch problem

    Replacing capacitors on the piezotg did not helped. One of the boards is still wrong.

    The chinese piezo button looks good now. It has a piece solid stainless steel body, looks nice and it works.
    The wiring is a bit stiff but it is not critical.

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