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I found this circuit on a page and i want to tried but i dont get why the capacitor is there ; any ideas why ? i'm kinda new to electronics
Float charger
- Thread starter Andres Hiden
- Start date
I found this circuit on a page and i want to tried but i dont get why the capacitor is there ; any ideas why ? i'm kinda new to electronics
The 100 uf capacitor is attached close to the regulator chip to allow the chip to get current very quickly when it switches on and diminish any of the impedance effects of the diode (D1). I think there should be a small capacitor on the output to stop the chip from oscillating. Check the datasheet for exactly which regulator chip you have.
It depends on whether the input voltage is DC or AC. If it's DC, it bolsters the input voltage during spikes in load current; not an issue for a battery charger, it will deal with any voltage sag. If it's AC, it also provides filtering.
R1 looks extraneous. Since it's in the feedback loop, it will affect regulation. LED1 seems extraneous because you have LED2 and no ability to disconnect the regulator.
A capacitor on the output would improve transient response; in your case, it's a don't care.
I'm not a fan of charging batteries in series if it can be avoided. Strong batteries will eventually kill weak ones.
Dyslexicbloke
- Joined Sep 4, 2010
- 566
A 317 is a floating regulator and will attempt to maintain a fixed voltage refrence at it sense pin relative to its output.
R1 is a current limit limit device... as current increeses the voltage after R1 will fall relative to the output of the regulator, increesing the refrence and thus causing the regulator to back off.
RCl and Q1 have a simmilar, but more dramatic effect. should a fault current occur Q1 will turn on pulling the ref very low and effectivly shutting the regulator down.
LED1 would reflect this shutdown condition, by being off, it also provides the required minimum load that the 317 requires when it is on.
A 317 can operate purly as a current limit having no ground connection at all. it can be entirly floated and will simply maintain its 1.25v refrence at sense.
An output capacitor is recomended in most circumstances.
Al
R1 is a current limit limit device... as current increeses the voltage after R1 will fall relative to the output of the regulator, increesing the refrence and thus causing the regulator to back off.
RCl and Q1 have a simmilar, but more dramatic effect. should a fault current occur Q1 will turn on pulling the ref very low and effectivly shutting the regulator down.
LED1 would reflect this shutdown condition, by being off, it also provides the required minimum load that the 317 requires when it is on.
A 317 can operate purly as a current limit having no ground connection at all. it can be entirly floated and will simply maintain its 1.25v refrence at sense.
An output capacitor is recomended in most circumstances.
Al
