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Thread: Need a bit of electrical advice

  1. #1
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    Need a bit of electrical advice

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I have built a modified popper roaster with a lot of help from this web site. I now have control over both fan speed and element temperature. The only thing I cant seem to work out is this:
    I bought an Illuminated switch and I want to wire it so that it will light up when it is on. It is a DPDT rocker switch
    here is the Jaycar link: http://www.jaycar.com.au/ShowLargephoto.asp?id=4430&IMAGE=
    It has 6 terminals on the back, here is what my wiring looks like: I have the active wire from the power source (240V) attached to terminal 1 and the other wire attached to terminal 2.
    What do I need to add to get the switch to light up? I asked one of the guys at JayCar and they said I needed to earth terminal 3 but I have tried this and it still doesnt work.


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    Re: Need a bit of electrical advice

    You may need a neutral to terminal 3.... its hard to know with out seeing the terminals and running a continuity tester over them.... but Im guessing that the guy at Jaycar saw terminal as a negetive/neutral terminal required for iluminating the switch.....

    Like I said, its hard to tell without testing.... I guess be sure that the active isnt being switched to the terminal 3, otherwise youill have a short.

  3. #3
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    Re: Need a bit of electrical advice

    Hmmm,

    Being a DPDT switch without indication, it would have 6 terminals. With indication it would need to have at least another single terminal for the Neutral. Perhaps the indication being touted is just a simple Neon and if it isnt working (and the switch is working properly) then I would suspect the neon is cactused....

    All the best,
    Mal.

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    Re: Need a bit of electrical advice

    Hope this isnt too dumb a question for here, I am on my way to building a roaster with help from Koffee Kosmo and all the other helpful members here , using a car window winder for a motor, and was hoping to use a computer power supply (delta electronics dps120ab) , is there a relatively easy way to find the 12v output , I have read some other threads about a similar excercise , but the member involved ditched the setup and got a stircrazy base instead . I m new to multimeters but can use one very basically, just dont want to go about a pointless exercise if there is a better option, Thanks Gaz

  5. #5
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    Re: Need a bit of electrical advice

    Quote Originally Posted by doryanthes link=1227303966/0#3 date=1227334601
    Hope this isnt too dumb a question for here, I am on my way to building a roaster with help from Koffee Kosmo and all the *other helpful members here , using a car window winder for a motor, and was hoping to use a computer power supply (delta electronics dps120ab) , is there a relatively easy way to find the 12v output , I have read some other threads about a similar excercise , but the member involved ditched the setup and got a stircrazy base instead . I m new to multimeters but can use one very basically, just dont want to go about a pointless exercise if there is a better option, Thanks Gaz
    Every PC power supply has the outputs marked and these are not to bad if looking for +3.3, +5V, -5V, +12V and -12V

    1: Some of thes have open cct protecting as they are switch mode type and that means that with out a load they will not work or can blow up.

    2: Any good PC power supply has the Voltages and the connections marked and include the current rating.

    Thus depending on the load and requirements of the 12V motor your going to use you may have to look at the rating of the power supply...

    A: Grnd = Black and +12V should be Yellow

    My spare ATX 400W is rated at 10A for 12V ( my other 450W is 16A at +12V) but again I would not want to be drawing 10A or greater for any length of time..

    What ever you do, be carefull when working / playing with electrons... Even a little can KILL.

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    Re: Need a bit of electrical advice

    Mal,
    theres no way the switch is busted. I have two and another member has one, and none of them work as they are currently wired. They couldnt all be broken.
    Here is the Jaycar description:
    DPDT Illuminated Rocker - Large Red . Mains Illuminated. DPDT 240V 15 amp. Black body,available in red or green illumination. Spade lug connections

    Does anyone out there have any experience with these type of switches?

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    Re: Need a bit of electrical advice

    Cheers AM that is what I needed , yes the PSU is rated at 15A for +12V , and the next thing is to get the requirements of the motor , I will check the rockwell specs , shouldnt be too hard to find, thanks for the warning, been stung before, luckily only low amp high volt yoww :o
    Thank you very much , kind regards from gaz,

  8. #8
    Mal Dimal's Avatar
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    Re: Need a bit of electrical advice

    Quote Originally Posted by Aaron link=1227303966/0#5 date=1227346895
    Mal,
    theres no way the switch is busted.
    Why not?

    Its possible that incorrect switches were binned in the store and everyone has just purchased DPDT Rocker Switches. Not that uncommon an occurrence you know.... :-?

    Mal.

    P.S.
    Out of interest, does the switch have a "Centre Off" position? Or, does it have only two positions... Off and On?

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    Re: Need a bit of electrical advice

    Hi *Aron
    Am i correct DPDT means double pole double throw.
    If it is double pole i am guessing you will need to connect one side to active and the other side to neutral.
    But you need to check switch with a meter first.
    BE SURE NOT TO SWITCH ACTIVE TO NEUTRAL 240V CAN KILL

  10. #10
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    Re: Need a bit of electrical advice

    Quote Originally Posted by liteglobe link=1227303966/0#8 date=1227352299
    Hi Aron
    Am i correct DPDT means double pole double throw.
    If it is double pole i am guessing you will need to connect one side to active and the other side to neutral.
    But you need to check switch with a meter first.
    BE SURE NOT TO SWITCH ACTIVE TO NEUTRAL 240V CAN KILL
    Sorry... That is incorrect and may lead to an electrical explosion at best and a huge fright. If you arent sure about this, much better to engage someone who knows what theyre doing and is licensed to repair mains powered devices. My background is Electrical Engineering with nearly 40 years experience with items many times more complex than this, so take my advice and get a licensed person to check this out for you....

    Mal.

  11. #11
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    Re: Need a bit of electrical advice

    I found an identical problem on a different forum.

    Heres a quote of one of the replies:

    looks like from the jaycar description that the neon inside is mains illuminated, so this switch is built for making / breaking 240v circuits and uses the 240v passing through it to illuminate the neon.

    if it has 6 poles, then thats what i think is happening.


    How many volts are you running through the switch?

  12. #12
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    Re: Need a bit of electrical advice

    Quote Originally Posted by Mal link=1227303966/0#2 date=1227329414
    Hmmm,

    Being a DPDT switch without indication, it would have 6 terminals. With indication it would need to have at least another single terminal for the Neutral. Perhaps the indication being touted is just a simple Neon and if it isnt working (and the switch is working properly) then I would suspect the neon is cactused....

    All the best,
    Mal.
    Thought thats what I wrote above TG.... :-?

    Mal.

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    Re: Need a bit of electrical advice

    Im running 240V through the switch, which is partly why I am asking for advice rather than just trying a few different combinations myself. The switch only has two positions, off and on.
    and I still dispute the broken switch claim as the other CS member who has this problem bought his parts in Brisbane and I am in sydney.
    Here is my lame wiring diagram so you can see where the switches sit in relation to everything else.


  14. #14
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    Re: Need a bit of electrical advice

    Well mate,

    The diagram hasnt appeared but from your description, the switch is NOT a DPDT but a DPST (Double Pole Single Throw) as a DPDT has a Centre Off position and can be switched either direction from the centre position, hence the Double Throw description.

    It may be, that one or both of a pair of the 6 terminals is intended for connection to the Neutral so as to provide the return path for the internal light bulb when the switch is turned On. The Jaycar description for the switch doesnt explain a lot unfortunately and anyway, it doesnt seem to apply to the switch you have.

    If possible, can you check the continuity of the terminal arrangements of your switch and identify which pair of terminals change state when switching Off and On and then transfer this to a sketch? Also, using your DMM set to its lowest Resistance setting, test across each pair of terminals to see if the light bulb is connected to one of the pair.

    Referring to the sketch below and with the Switch in the Off position, can you identify which terminals are Closed, Open and whether you detect a resistance across terminals 1 and 4 or 3 and 6? Should be able to help you out once we have that info. All the best mate,

    Mal.


  15. #15
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    Re: Need a bit of electrical advice

    Quote Originally Posted by Mal link=1227303966/0#11 date=1227369523
    Quote Originally Posted by Mal link=1227303966/0#2 date=1227329414
    Hmmm,

    Being a DPDT switch without indication, it would have 6 terminals. With indication it would need to have at least another single terminal for the Neutral. Perhaps the indication being touted is just a simple Neon and if it isnt working (and the switch is working properly) then I would suspect the neon is cactused....

    All the best,
    Mal.
    Thought thats what I wrote above TG.... :-?

    Mal.
    That was 8 posts back and my memory aint what it used to be.
    And also in my defence, you did mention a 7th terminal.

  16. #16
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    Re: Need a bit of electrical advice

    ;) ;D ;D ;D.......

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    Re: Need a bit of electrical advice

    Aaron

    Be careful, remember you are playing with VERY dangerous voltages.
    I think it best to follow Mals advise and get a qualified person to check this out.

    Otherwise, please be aware there is a huge variety of switch combinations available.
    To avoid any further confusion, as Mal suggests, remove all wires, and buzz out the switch, and post a diagram so we clearly understand what is going on.


    Ive used similar looking switches, but I cannot say they are the same as yours.
    In those Ive used, If you look closely at the terminals you could see two fine wires connected one of the sets of terminals.
    These fine wires are physically connected to the neon globe.
    Using Mals suggested numbering as a reference I would expect the globe would be connected to either 1 & 4 or 3 & 6 [but not both].

    Of course in a differently constructed switch the neon globe wires differently connected and may not be visible at all.

    With the switches I have used, the neon will only light if one pole switches the active and one pole switches the neutral, and of course the globe must connected electrically on the switched side.


    Mal,
    it may be "Mr Semantics" knocking at my door, but I thought DPDT could describe a switch with two or three "physical" positions.

    Two "physical" positions could still give you two throws [ie one way or the other] but without a centre off, The proviso would be that the "wiper" was wired as "common" ......eg ON ON

    Depending on manufacturing intent, Three "physical" switch positions will usually give you a centre OFF .....ie .... ON OFF ON so these also give you two throws.

    Sometimes [like for guitar pickup switching] other combinations can be manufactured eg.......ON ON ON.


    cheers and be careful out there!


  18. #18
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    Re: Need a bit of electrical advice

    No worries, I am definitely scared enough of 240V to be very careful having copped a full zap once in my life as a kid, I am not keen on doing it again any time soon.
    Everything is wired up and working at this point - with the exception of the switch lights turning on. So you can imagine how reluctant I am to unsolder the switch to test it out. Especially when a couple of Kilos of sumatran has just turned up on my doorstep.
    The other thing is, I dont know my way around a DMM very well and I am not sure that i could do the things i need to to get Mal his information to help me out.
    I guess i will just have to wait and see if I can get someone who knows what theyre doing to take a look.
    On the upside I did score a great piece of stainless tube for the chimney today.

  19. #19
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    Re: Need a bit of electrical advice

    Gday reubster...

    Harking back to my Switchboard/Switchgear Designing days.... ::)

    When referring to any kind of toggle switch (of which a rocker switch is a variation), DPDT refers to an Off, On 1 and On 2. Most usually, the Centre Position is the Off position but it can be such that full up is Off with the nest two positions being the alternative On positions. Variations other than this would be specific designs for a specified purpose and not considered to be Double Pole - Double Throw.

    Heres a link that describes the basics... http://tinyurl.com/6b7tbr

    Mal.


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    Re: Need a bit of electrical advice

    Hi Aaron,

    did you figure this out in the end? I am pretty sure I will be needing one of these switches also - just hte right size for my pavoni. So off to Jaycar in the next few days.

    It is weird they call ita DT - always my understanding that would be 3 positions, but I only want two anyway, so thats good for me.

    Damian.

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    Re: Need a bit of electrical advice

    Hi Aaron, * looking at your diagram, I would have put the active input to the centre terminals, and seeing as you have bought 2 poles , why not use them, and switch the neutral input as well.

    Who knows the thing may just light up then. Anyway switching both active and neutral would have to be inherently safer, have heard stories of appliances being incorrectly wired with the switch only breaking the neutral line on the way back to the power station, with the device effectively live when switched off.

    It does sound like a single throw switch though from your description. maybe *terminals 3 and 6 are not connected internally.dpst - on / off switching 2 terminals - 1 & 2 and *4 & 5.

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    Re: Need a bit of electrical advice

    I pulled open a SK0983 from jaycar. Using mals diagram, it switches 1 to 2, or 2 to 3. On the other side it switches 4 to 5 or 5 to 6. 2 to 5 has a resistor and globe between them.

    So say in off position, 1 is linked to 2. then 4 is linked to 5. Active would go to 3 and neutral to 6. Coffee machine would go to 2 and 5. Then when switched, hopefully coffee machine and light would come on.

    Anyone think this is incorrect?

  23. #23
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    Re: Need a bit of electrical advice

    Damian1
    I think you are correct although others on cs may think differently
    "THIS CAN LEAD TO AN ELECTRIAL EXPLOSION"

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    Re: Need a bit of electrical advice

    Thanks liteglobe - one person thinking the same is enough for me! I just plugged in to mains without machine on the other end, and it lit up as expected. Excellent!

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    Re: Need a bit of electrical advice

    Quote Originally Posted by Mal link=1227303966/0#13 date=1227442961
    Well mate,

    The diagram hasnt appeared but from your description, the switch is NOT a DPDT but a DPST (Double Pole Single Throw) as a DPDT has a Centre Off position and can be switched either direction from the centre position, hence the Double Throw description.

    It may be, that one or both of a pair of the 6 terminals is intended for connection to the Neutral so as to provide the return path for the internal light bulb when the switch is turned On. The Jaycar description for the switch doesnt explain a lot unfortunately and anyway, it doesnt seem to apply to the switch you have.

    If possible, can you check the continuity of the terminal arrangements of your switch and identify which pair of terminals change state when switching Off and On and then transfer this to a sketch? Also, using your DMM set to its lowest Resistance setting, test across each pair of terminals to see if the light bulb is connected to one of the pair.

    Referring to the sketch below and with the Switch in the Off position, can you identify which terminals are Closed, Open and whether you detect a resistance across terminals 1 and 4 or 3 and 6? Should be able to help you out once we have that info. All the best mate,

    Mal.
    If your switch is like Mal discribed in his pic;
    The active wire from power supply should go on terminal 1.
    The neutral wire from power supply on terminal 4.
    The active wire from device (motor or element) to terminal 2.
    The neutral wire from device to terminal 5.

    If the neutral wire on the device is earthed connect terminal 5 to earth.

    The switch should be switching terminal 2 between terminal 1 and terminal 3, aswell as terminal 5 between terminal 4 and terminal 6. the globe is between terminal 2 and 5.

    Hope this makes sense and is of help.

    Good luck.

  26. #26
    A_M
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    Re: Need a bit of electrical advice

    WARNING:

    QLD has just made further changes to the Electrical *Act and are taking a hard line on activities that compromise the safety of the user or *impacts on the system its self.

    The Electrical Safety Board launched the new Electrical Safety Plan for Queensland 2009-2014 on 4 December 2008 to take effect from 1 January 2009.

    Launching the plan, Commissioner for Electrical Safety Jack Camp said the planís five year goal is to eliminate all preventable electrical deaths in Queensland.

    This aligns with the purpose of the Electrical Safety Act 2002, which aims to eliminate the human cost to individuals, families and the community of death, injury and destruction that can be caused by electricity.


    We see more deaths through misadventure and electrical shock in one year in QLD, than have been killed in 7 years of OS action by our troops.

    In QLD if a person is presenting to a Dr or Hospital with suspected shock; then it is LAW that the icedent has to be reported to the ESO and then investigated. Not unlike reporting a gun shot wound.

    Stay safe.... If you do not know what your doing and or not licensed (QLD is the strictest) then dont take the chance..

  27. #27
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    Re: Need a bit of electrical advice

    Behmor Coffee Roaster
    yep. No need to be concerned. I wouldnt do it if there was any risk. it is all sorted anyway - the issue was how to get it to light up - which was pretty obvious in the end.

    Damian.



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