Need Help! passing 12 v throught pc817


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    Default passing 12 v throught pc817

    hello guys , I need to pass 12v current via an aptocouplor pc817 when i test it with a led it turn on but with a fan (12v) it doesn't work please help


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    Attached Thumbnails Attached Thumbnails passing 12 v throught pc817-azerty-jpg   passing 12 v throught pc817-azerty-jpg  


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    Default Re: passing 12 v throught pc817

    PC817's "absolute maximum" collector current is 50mA. It is not capable of driving any 12V fans, not even small CPU cooler fans. If you connected PC817 as shown in your drawing, it's already dead.

    You need to do something like this:
    passing 12 v throught pc817-sugw6-jpg

    The choice of MOSFET will depend on the current rating of your fan.



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    Default Re: passing 12 v throught pc817

    Opto Isolators doesnt work that way sir, it`s basically a small photo sensitive switch, you need a driver transistor to ramp up the amperage on the opto switch to trigger the coil of the 12VDC relay then magnetize the switch inside the relay to switch your 12VDC fan

    passing 12 v throught pc817-1-jpg

    or if you want to do a shortcut in assembling electronics, better just buy a solid state relay rated 30VDC @ 100 amp ( or it depends on your fan amperage) on the main switch, 3-32 VDC on the input

    passing 12 v throught pc817-2-jpg



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    Default Re: passing 12 v throught pc817

    Agree with KHOUJ, get a solid state relay they come in AC and DC versions, you need the DC version but as the previous user pointed out this will allow you to run your fan with no issues at all.
    Russ



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    Default Re: passing 12 v throught pc817

    thank you all
    but can any one draw an electrical circuit using relay knowing that my fun works with 12v I use L7812CV



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    Default Re: passing 12 v throught pc817

    The circuit would be identical to the one you drew with the OPTO on the very first post. In fact look at the photo that KHOUJ posted, You Adrino output would go to the input voltage pin he has painted red. This signal can be anywhere from 3V to 32VDC. The high output of the Adrino will drive this with no issue it takes very little current to activate the solid state relay. The output of the relay has one side go to the FAN the other side go the 12V supply and the common from the supply ties to the other side of the fan. Very simple. Works perfect.

    Russ



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    Default Re: passing 12 v throught pc817

    passing 12 v throught pc817-circuit-png

    please check this



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    Default Re: passing 12 v throught pc817

    Quote Originally Posted by dallli92 View Post
    passing 12 v throught pc817-circuit-png

    please check this
    If you plan to use the solid state method, you can take out the outside opto coupler, the solid state relay already had it`s opto isolator inside.

    by the way I do make projects too on arduino anything that I can think of, pretty much addicting.

    passing 12 v throught pc817-20170401_070810-jpg



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    Default Re: passing 12 v throught pc817

    in fact all i want is getting temerature from the arduino and when it> 25 i want to start on the fan
    so I can take the pc817 off and just use the 3-32vdc?
    and what about the output value from the 3-32vdc is it 12 exactly ?



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    Default Re: passing 12 v throught pc817

    Quote Originally Posted by dallli92 View Post
    in fact all i want is getting temerature from the arduino and when it> 25 i want to start on the fan
    so I can take the pc817 off and just use the 3-32vdc?
    and what about the output value from the 3-32vdc is it 12 exactly ?
    Yes sir, you can safely take out the PC817 on the circuit, on the output side of the solid state relay it`s not making any output voltage, it will just "switch" any load safely within the SSR`s specification, let` say if you use a 12VDC on the output, it will that switch the 12VDC voltage to your 12VDC fan, on the input side of the SSR it`s completely isolated on the output voltage because it had a bulit in opto isolator inside.


    If it`s only a simple temperature switch I think it`s more simple and practical to just use an automotive thermostat like this on the picture?



    or if you want to make it electronic then use this?



    or try to find a 12VDC CPU fan with built in thermo resistor, I had one here laying around, Im pretty sure you can calibrate this with a simple 1/4 watt resistors according to your temperature preference, what it does is when you supply it with 12VDC it will just run 600 rpm, the moment the thermo resistor senses an increase of temperature of the air it will gradually adjust it`s speed depending on the temperature, the thermo resistor is located in front of the exhaust air flow of the fan itself.

    Attached Thumbnails Attached Thumbnails passing 12 v throught pc817-pl6480820-custom_made_air_conditioner_thermostat_for_bus_and_car_temp_range_0_35_c-jpg   passing 12 v throught pc817-1f82_0261_emerson_clip-jpg  


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    Default Re: passing 12 v throught pc817

    The OP stated that he is powering his fan with a 7812, which means it's just a small fan like the one used in computer power supplies. Driving it with a solid state relay is an overkill in terms of size and cost. A tiny surface mount transistor that costs 50 cents will work just as good.



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    Default Re: passing 12 v throught pc817

    Quote Originally Posted by CitizenOfDreams View Post
    The OP stated that he is powering his fan with a 7812, which means it's just a small fan like the one used in computer power supplies. Driving it with a solid state relay is an overkill in terms of size and cost. A tiny surface mount transistor that costs 50 cents will work just as good.
    Yep I know that sir, im just adjusting to what he can do to finish his project as simple as possible, on my level of computer / electronic knowledge I can control a fan on just about anything, but he`s not me I need to simplify my suggestions for him to understand easily.



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    Default Re: passing 12 v throught pc817

    Dalli,
    the L7812 is a simple three pin regulator for 12V. You input a voltage like 18V to 24V into pin#1 and the center pin is ground, and the third pin is 12VDC output. The 12V output would connect to the solid state relay. The input to the solid state relay already contains a photo transistor and only requires a very small amount of current to turn on, the Ardrino can handle this easily.

    Russ



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    Default Re: passing 12 v throught pc817

    Quote Originally Posted by dallli92 View Post
    in fact all i want is getting temerature from the arduino and when it> 25 i want to start on the fan
    so I can take the pc817 off and just use the 3-32vdc?
    and what about the output value from the 3-32vdc is it 12 exactly ?
    Sorry sir let me clarify it to you, the 3-32VDC indicated on the input of the SSR is that you can put a 3VDC voltage on it then it will switch ON the output state, you can even trigger it with only a multimter test rods put into 200 ohms resistance, the voltage on the test probe of the multimeter that is set to 200 ohms is enough to trigger the ON state of the SSR, you can turn it ON up to 32VDC trigger, the output capacity on the SSR picture says it can handle loads up to 100 amp @ 30VDC, meaning the SSR can switch or handle any load @ a maximum of 100 amp in the range of 30VDC maximum, so meaning any load lesser than 100 amp. 30VDC he can handle it perfectly, you can buy a solid state relay rated in only 1 amp @ 30VDC, I have plenty here lying around, it`s a much smaller than that of the picture I posted, same thing, you can trigger it with only a test probe but it`s switch capacity is only 1 amp. at any voltage range below 30VDC



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    Default

    can you please show me a picture of it and the exact reference to buy it. thank you



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    Default Re: passing 12 v throught pc817

    Quote Originally Posted by dallli92 View Post
    can you please show me a picture of it and the exact reference to buy it. thank you

    1 Channel SSR Solid State Relay high-low trigger 5A 5v12v For Arduino uno R3 | eBay



    here you go sir, the input voltage on this is 3-32VDC, the output can handle up to 5A 5V-220VDC, you can directly feed it to your arduino output state to switch control your 12VDC fan

    Attached Thumbnails Attached Thumbnails passing 12 v throught pc817-s-l1600-jpg  


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    Default Re: passing 12 v throught pc817

    I looked in old devices and I found this is it good for my case ?
    if yes please tell me about these pins because it is not clear


    Attached Thumbnails Attached Thumbnails passing 12 v throught pc817-20170401_215529-jpg   passing 12 v throught pc817-20170401_215444-jpg   passing 12 v throught pc817-20170401_215458-jpg   passing 12 v throught pc817-20170401_215515-jpg  



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    Default Re: passing 12 v throught pc817

    Can you please post the picture of your fan sir? so that I can see how big of a switch you need, lets do it the NPN transistor way, on that picture it`s a simple relay 12VDC, you can use that too if you want, but it needs a triggering transistor because arduino GPIO output is only 5VDC, for sure you can also buy a 5 volt relay but it`s scarce, let`s just use the NPN transistor to switch your fan ON/OFF, but first I need to know how big is your fan inorder not to burn the transistor itself.



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    Default Re: passing 12 v throught pc817

    the fan passing 12 v throught pc817-nnn-jpg



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    Default Re: passing 12 v throught pc817

    Here you go, just use a single 12VDC power supply, no need to have two voltages, the arduino had it`s own surface mount 7805 regulator if you use the DC connector, I also have a couple of arduino boards here lying around, on the transistor just use NPN TO 220 package, (TIP 31, TIP41C etc.) in that way you dont have to put a heatsink on it, use a 1/4 watt resistor, on the diodes use any 1 amp. you can find, it`s just a voltage feedback blockers. your CPU fan is from socket AMD am I right?

    passing 12 v throught pc817-1-jpg



    passing 12 v throught pc817-f4859755-01-jpg



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