Please help to provide me a complete circuit for the Half Wave Controlled Rectifier. I have searched many times in the internet but i could not find any complete circuit wif the firing circuit to fire the SCR.
I think he means a 'controlled' rectifier, which uses SCR's instead of diodes and they are only turned on as needed by the load, and the turn on point is determined by the control circuit, which is what he seems to be looking for.
The SCR gate voltage isnt that accurate so you can not really depend on turning it on using the gate characteristics as the backbone for the design. Usually some sort of trigger circuit is used to fire the gate and that is what turns the SCR on. It can be a short pulse and then turn off until the next required firing of the SCR.
What is it that you are trying to build?
actually i am building tis half wave controlled rectifier to convert AC supply to DC. After that the DC will drive a dc motor. i really cant quite figure out how to build this circuit...
actually i am building tis half wave controlled rectifier to convert AC supply to DC. After that the DC will drive a dc motor. i really cant quite figure out how to build this circuit...
I am missing a few things here. How large is this DC motor as in how much current does it draw and what is the voltage of the DC motor? I don't understand why Half Wave is mentioned? Are you trying to vary the motor speed of a large DC motor using SCR control?
Maybe if you could explain in detail, including voltages and currents exactly what you want to do this would go much, much better.
You can probably take any triac circuit and make it into a half wave'r simply by only firing on one half cycle of the wave. It shouldnt be that hard, or maybe even using an SCR where the triac normally goes. I personally dont like the diac based firing circuits because the diac doesnt turn on soon enough for every low speeds, but you may find it acceptable in your application it's hard to say without knowing exactly what you are using this for.
I have seen circuits posted right here on ET forum for triacs so if someone would be nice enough to search a little for one. One that looked especially nice used a 555 as the main part in the trigger circuit, which provides very nice triac or scr control.
While we are on the subject, why exactly do you want to use half wave control anyway, rather than full wave control?
Boncuk:
Well there are some SCR based circuits that can fire on both half cycles making it full wave. Two SCR's obviously but even a single SCR circuit can do it.