CCCV circuit using opamps. - Electronic Circuits Projects Diagrams Free

neelam29 · 28th April 2008, 06:19 AM

Dear frnds
i want to design a simple circuit which gives constant current 1A and constant volatge 48V using simple opamp or any ICs.please help me out.

dknguyen · 28th April 2008, 06:51 AM

You can't have constant voltage and constant current at the same time unless you have a constant load. You either adjust the voltage to keep the current constant, or you adjust the current to keep the voltage constant.

If you have a constant load, you don't need to make a constant current/voltage source since the load never changes. For a given load, you can only pick either the voltage or current you want through it, not both. If you pick voltage, the load will decide what the current will be. If you pick the current, the load will decide the voltage.

So your question makes no sense.

neelam29 · 28th April 2008, 07:10 AM

okie. so i need to keep only one thing constant. if i want to keep my volatge constant 48V then how will ckt design out to be.

blueroomelectronics · 28th April 2008, 07:38 AM

Telling us what it's for is often helpful.

dknguyen · 28th April 2008, 08:19 AM

Get a DC voltage supply of larger than 50V or a bit larger. Get a 48V zener diode and an op-amp that can source your desired current (about 1A right?) and tolerate your voltage supply.

Make a voltage follower or buffer with the op-amp and use the zener diode (with a resistor) to make a 48V reference to feed into the voltage follower inputs. The op-amp should replicate the 48V of the zener, but with higher current drive.

Or you can use transistors instead of the op-amp voltage follower:
http://en.wikipedia.org/wiki/Linear_regulator

You could just use a resistor and zener diode, but I get the feeling your current requirement is too large for the zener diodes that you can probably get your hands on.

neelam29 · 28th April 2008, 07:12 PM

It will be used for heavy electrolysis process..

blueroomelectronics · 28th April 2008, 07:44 PM

Does electrolysis need regulation? You might be able to use an LM317 as a series regulator for the current.

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28th April 2008, 06:19 AM	(permalink)
neelam29	CCCV circuit using opamps. Dear frnds i want to design a simple circuit which gives constant current 1A and constant volatge 48V using simple opamp or any ICs.please help me out.

28th April 2008, 06:51 AM	(permalink)
dknguyen	You can't have constant voltage and constant current at the same time unless you have a constant load. You either adjust the voltage to keep the current constant, or you adjust the current to keep the voltage constant. If you have a constant load, you don't need to make a constant current/voltage source since the load never changes. For a given load, you can only pick either the voltage or current you want through it, not both. If you pick voltage, the load will decide what the current will be. If you pick the current, the load will decide the voltage. So your question makes no sense. __________________ NO, that picture isn't me so don't bother asking if we can be friends. Last edited by dknguyen; 28th April 2008 at 06:55 AM.

28th April 2008, 07:10 AM	(permalink)
neelam29	okie. so i need to keep only one thing constant. if i want to keep my volatge constant 48V then how will ckt design out to be.

28th April 2008, 07:38 AM	(permalink)
blueroomelectronics	Telling us what it's for is often helpful. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

28th April 2008, 08:19 AM	(permalink)
dknguyen	Get a DC voltage supply of larger than 50V or a bit larger. Get a 48V zener diode and an op-amp that can source your desired current (about 1A right?) and tolerate your voltage supply. Make a voltage follower or buffer with the op-amp and use the zener diode (with a resistor) to make a 48V reference to feed into the voltage follower inputs. The op-amp should replicate the 48V of the zener, but with higher current drive. Or you can use transistors instead of the op-amp voltage follower: http://en.wikipedia.org/wiki/Linear_regulator You could just use a resistor and zener diode, but I get the feeling your current requirement is too large for the zener diodes that you can probably get your hands on. __________________ NO, that picture isn't me so don't bother asking if we can be friends.

28th April 2008, 07:12 PM	(permalink)
neelam29	It will be used for heavy electrolysis process..

28th April 2008, 07:44 PM	(permalink)
blueroomelectronics	Does electrolysis need regulation? You might be able to use an LM317 as a series regulator for the current. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com