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Hand Sanitiser Dispenser Circuit

Discussion in 'General Electronics Discussion' started by waitingfor, Sep 10, 2015.

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  1. waitingfor

    waitingfor

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    Sep 9, 2015
    Hi there,

    I'm totally inexperienced when it comes to electronics, and circuit editing/building(?), but for a project I am about to embark upon I need to deactivate the sensor and add a timer to an existing circuit board in order for it to dispense gel every five minutes, regardless of whether there is a hand underneath it.

    Can anyone here help? And if I've directed this to the wrong part of the forum, please point me in the right direction. I have a small budget for anyone who might want to take this on as a project, but either way I'll look forward to hear your suggestions.

    Thanks,

    I

    IMG_8657.JPG IMG_8664.JPG IMG_8666.JPG
     
  2. Old Steve

    Old Steve

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    Jul 23, 2015
    A timer chip could simply tack in at the IR detector/receiver stage and trigger it regularly, I'd say.

    I'm wondering what those coils are for.
     
    waitingfor likes this.
  3. AnalogKid

    AnalogKid

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    Jun 10, 2015
    You could contact xxx Wave Technologies (name on the pcb) to wee if the want to help. A small change to the PIC firmware will do what you want.

    ak
     
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  4. Old Steve

    Old Steve

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    Jul 23, 2015
    Yeah, I was going to mention that the PIC could probably be re-programmed in-circuit, but contacting them would be a good idea if it's going to be a production run. They probably wouldn't be interested in helping with a one-off, though, since they'd have to write the code and re-program the chip.
     
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  5. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Perhaps a solenoid for dispensing gel?
     
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  6. Old Steve

    Old Steve

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    Jul 23, 2015
    I thought the motor did that on it's own. But you may be right - a solenoid to open a valve, then the motor to pump the gel, since gravity may not be enough.
     
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  7. waitingfor

    waitingfor

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    Sep 9, 2015
    Thanks so much for this suggestion, I was wondering if there would be a chip that I should look out for, one that would be particularly suited/compatible?
     
  8. waitingfor

    waitingfor

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    Sep 9, 2015
    You're right in thinking this isn't something that will be going into production, there will just be a few units at most. But it would only be the pcb manufacturer that would have the ability to re-programme the circuit?
     
  9. Old Steve

    Old Steve

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    Jul 23, 2015
    Since you said "I'm totally inexperienced when it comes to electronics, and circuit editing/building(?)", I assumed that you wouldn't be able to do it yourself.
    Also, the circuit would need to be traced to see what connects to what, before someone else could write suitable firmware. That in itself could be pretty tricky, if not impossible, especially considering that the board has those 'blob' ICs on it. No telling what's in them.

    It would depend, too, on whether the original PCB was set up for in-circuit serial programming of the chip. The chip may have been programmed before being placed onto the PCB. I can see a couple of pads on the edge of the PCB that are connected to the chip, though, along with three others that are probably connected to it, so it was most likely originally programmed in-circuit.

    An NE555 timer IC, or TLC555, would probably do the trick, along with a transistor. Some fiddling/testing would be needed to determine if it would work and where to connect it though.

    Otherwise, the original PCB could be discarded, and a new circuit could be put in instead.

    As an aside, the original PCB seems to have a hell of a lot of electronics for such a relatively simple task. I guess it must have been needed though.
     
    Last edited: Sep 10, 2015
    Tha fios agaibh likes this.
  10. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Uh ... I'd give better odds on seeing a cow fly! :p

    Chris
     
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  11. waitingfor

    waitingfor

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    Sep 9, 2015
    Thanks for you help Steve. So it sounds like I may have to seek out somebody to remake the board. Is this the place to ask on this forum, or is there another section/forum where I could post a job? As long as it isn't too difficult to ship PCBs, I could work with someone internationally...
     
  12. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    Sir Waitingfor

    Here are my mechanico/technico perceptions from your pictorial data as being provided:
    That the units initial activation is being dependent upon an approaching hand establishing reflectivity of a LED light emitte source as per my
    markup, reflecting onto a sensor *** to then establish a dispensal cycle. (***A la the yellow arrow.)

    Now since you have his torn down, I can see that the unit is powered via 4 D cells via the loose red and black wires .
    As others, I also am being curious about the black coiled assembly with its two enamelled wire windings.
    Its connector is being near to a black epoxy COB (Chip On Board ) and if connected to that, one might expect a sensing type of function being
    initiated with the coil(s).

    SINCE the windings are appearing relatively minimal in restect to performing some moderate mechanical or electromagna-mechanical function, plus
    I see no power related driver semiconductors nearby to its connector Molex..

    Soooooooooo exactly WHERE was the coil assenbly taken from, in the mechanical assembly aspect of the unit.
    If being a sensor, it might be up near the dispenser mechanics, and is related to the timing of a dispense cycle and shut off .

    OR another possibility, being :

    Is the activation of the lever micro switch that I have marked up, being associated with activation by the gear trained motor, such that is detecting
    /establishing duration or end of dispensing cycle ?
    Do you see that mechanical action happening ?

    Or possibly, this is connected to a lever such that it is being an OPTIONAL mechanical activation mode for the unit, vice the reflected light
    sensor..

    The Fine lined Red Box points out the power Micro FET's H-bridge driver configuration and their bipolar pre drivers for the motor unit.

    Also there is the small tact switch I marked up, is there any lever machanics tied to that, or possibly, it is just being a U2 microprocessor reset
    switch.

    The units instruction manual should explain that aspect, if being so.

    Also, is this possibly being a Go-Jo or Purell unit or from their Sugar Daddy . . . . . Dispenserhelp ?

    Now for some info in the seeking out of a simple solution to your quest.

    The Emitter and Sensor are optically coupling, using their invisible IR beam of light, reflecting from an approaching hand.

    The question now is it possible for you set up the unit and initially trip it with your hand approaching and then see if it will retrip again just as

    soon as it has dispensed, or is some wait time involved ?

    After establishing the units "lock out time", see if you can cover the Emitter unit, with a square of black elecrical tape and then see if waving a

    bright flashlight beam in front of the Sensor will flood/swamp it and trip off a dispense cycle.

    IF NOT, then locate your household laser pointer and initially warm it up a bit by darting its beam around the floor in front of the family cat and
    give her a real workout with some sharp turns. Finally, crash the cat into the wall . . . . in chasing it.

    Then, you do not want to damage the sensor, but get about 5 ft away from the sensor and catch it in a sweep that is moving such that its speed
    of travel is covering about a foot per second.
    If that did not trigger a cycle , you might try getting to the side of the sensor and not be going DIRECTLY into the sensor, but instead be hitting
    the side of the lucite lens /cover and let that indirect light input possibly trigger he unit.

    That's about all that I initially would want to know.

    Standing by . . . . .

    Mark up of your photo :

    [​IMG]


    Alternate Hosting site availability:
    http://i.imgur.com/jRe6xcY.jpg




    73's de Edd
     
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  13. Old Steve

    Old Steve

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    Jul 23, 2015
    ^ A hard act to follow. :D
    73's de Edd is definitely on the right track.

    Interfacing with the current board is still the best way to go, before considering getting a board made by someone. It's still just a matter of using a timer to trigger it, possibly simply switching across the IR receiver, as I mentioned in my first post. It's a matter of figuring out how to do it from a distance.

    Some of the questions 73's de Edd asked are pretty important.
    1. Where does that coil thing attach to the mechanics when the unit is assembled?
    2. What is the purpose of the lever-operated microswitch?
    3. What is the purpose of the small tactile pushbutton switch?

    (Regarding the laser pointer and the cat, I have a little Jack Russell Terrier who loves to chase the light from a laser pointer or even a torch. Pretty funny to watch. He really believes that the light circle is a solid object that he could catch if only he was quick enough. :D )
     
  14. waitingfor

    waitingfor

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    Sep 9, 2015
    Thanks 73's de Edd!

    I'm away from the unit for a couple of days, but when I get back to it I'll be able to answer these questions hopefully! I have also ordered a new one for speed and quickness when it comes to looking at the board, looking at a working unit...
     
  15. waitingfor

    waitingfor

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    Sep 9, 2015
    Thanks Steve, see above post - I'll be looking at this all again on Tuesday. So if and when I get a dog or cat, I'll be sure to have a laser pointer whenever there's a need for a quick distraction!
     
    Old Steve likes this.
  16. wingnut

    wingnut

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    Aug 9, 2012
    My temptation would be to desolder the ir emitter and glue it to the sensor so that it is permanently on (permanently thinks that a hand is there). Or put a piece of silver foil where the hand is to fool the sensor into thinking that it needs to be permanently on. Then I would add a 555 timer chip where the desoldered emitter once was and get this to switch on every 5 minutes for a few seconds. The output pin from the 555 timer would be to the original, desoldered ir emitter.

    In summary, the 555 would activate the emitter every 5 mins which would activate the sensor causing the motor to dispense liquid.

    And if you want to simplify it further, turn the dispensing bottle upside down with a small hole at the bottom like a water clock dripping into a Japanese water fountain which fills and then suddenly tilts over to dispense liquid every 5 mins. Solved without any electronics.
     
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  17. Old Steve

    Old Steve

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    169
    Jul 23, 2015
    Your first idea isn't bad at all.

    Your second idea is blasphemy. :D
    No electronics! Bah humbug.
     
    Last edited: Sep 15, 2015
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