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dear sir , in my project the control voltage is 0 to 5 V and this control voltage use we varies the the heater which is 230 v operate.suppose output control voltage is 5 volt then heater operate 230 v if control voltage is less then 5 then heater works less then operate 230 v. using these we temperature controlling of tank . so , kindly help me for this types of circuit design....

 

 

 

 

 

 

thanks..

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  • If i understand correctly, you need to control power with 0-5V signal.
    The simplest way to do that in my perspective is to use ramp voltage generator 0-5V and comparator to compare it with 5 volts. Ramp frequency should be around 1kHz. What you will get is PWM signal.

    Now you need to rectify mains voltage and use power mosfet, n channel. This is what i do in my solder reflow oven power control, i get 15b resolution  for 1kW heater.

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  • If i understand correctly, you need to control power with 0-5V signal.
    The simplest way to do that in my perspective is to use ramp voltage generator 0-5V and comparator to compare it with 5 volts. Ramp frequency should be around 1kHz. What you will get is PWM signal.

    Now you need to rectify mains voltage and use power mosfet, n channel. This is what i do in my solder reflow oven power control, i get 15b resolution  for 1kW heater.

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  • in reply to Kilohercas

    If you are controlling the temperature of water in a tank there is no need to have proportional control of the heater power if the heater size is suitable for the tank. You can turn the heater on for a whole number of mains cycles and then off for a different number of cycles (best to use whole cycles because the switching can be at the mains zero crossing point for least electrical noise generation). If the heater is on for 50 cycles and off for 200 cycles the power is reduced to 1/5 of the power of continuous running. You can  buy a ready made zero crossing switch device to switch the load.

    You could make a cicruit like Linas suggests to control the zero crossing switch.

     

    MK