is this a half wave rectifier?

Thread Starter

kirayamato_143

Joined Jan 23, 2011
59
i want to know if d1 is a half wave rectifier cause I'm thinking to connect it directly to my power supply with 12v and 9v output directly to BR2 the full wave rectifier taking d1 out of the schematic,,i attached the photos
 

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SgtWookie

Joined Jul 17, 2007
22,220
i want to know if d1 is a half wave rectifier cause I'm thinking to connect it directly to my power supply with 12v and 9v output directly to BR2 the full wave rectifier taking d1 out of the schematic,,i attached the photos
Yes, D1 is a half-wave rectifier. It appears offhand that the circuit is a lead-acid battery charger.

I don't know what you're talking about with the 2nd part; that isn't a power supply, it's an audio amplifier.

A 12v lead-acid battery would need a higher input voltage to charge it.
 

SgtWookie

Joined Jul 17, 2007
22,220
i just wanna ask now how to simulate a battery charger in proteus,,please help me i dont know..
Why don't you put that 1st circuit you attached in Proteus?

Instead of a battery, use a large capacitor to simulate a battery, with a 10m Ohm resistor in series with the cap, and a 10k resistor in parallel. It would be good to start the battery off with an 11.4v charge, which would be a 100% discharged battery.

There is a somewhat similar battery charger in the Completed Projects Collection forum. Have a look at this thread:
http://forum.allaboutcircuits.com/showthread.php?t=6099

You can use many other opamps than the one shown, as long as it's better than a 741.
 

Thread Starter

kirayamato_143

Joined Jan 23, 2011
59

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Thread Starter

kirayamato_143

Joined Jan 23, 2011
59
why is that so? but the site say it turns off the led when full charge i just dont know if it cease to charge also after full charge,, i really have to start reading to lessen my questions,,sorry,,but please bear with me,,i'm new in electronics
 

SgtWookie

Joined Jul 17, 2007
22,220
There are LOTS of schematics floating around the Internet that people never simulated, let alone build and got working. I have seen many really bad circuits out there. I have made a few poor ones myself. :rolleyes:

The LED will turn on when charging starts, but as charging progresses, the LED will slowly dim and turn off. Exactly WHEN that happens depends upon the Vf of the LED and the charge on the battery, which is really not the way to do things.

The charge current remains constant for awhile, then starts dropping as the regulator output voltage gets within several volts of the input voltage. The output termination voltage is entirely dependent upon the unregulated input voltage. It actually does terminate the charge, but at a voltage that you have no control over, and it does not monitor the battery temperature which is critical for a NiMH battery. Unless you monitor the temp and look for the "bump", you won't be able to really tell when the charge current should be turned off.
 

Thread Starter

kirayamato_143

Joined Jan 23, 2011
59
thanks,, yeah thats really a problem i dont master my proteus and so need to trust schematics from the internet,,sorry to ask for a solution to my problem but its something least i can do,, can you point me to an easy and working schematic for 9v nimh charger that automatically turns off upon full charge and recharge the battery again if needed without human intervention? sorry to ask like spoonfeed
 

SgtWookie

Joined Jul 17, 2007
22,220
I don't have one for a NiMH. You really need to monitor the temperature along with the voltage. That requires either a dedicated charger IC with supporting components, or to program a microcontroller with supporting components.

You also have to follow the battery manufacturer's recommendations for charging.

Don't use a NiCD charger for a NiMH, as they are different technologies.
 
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