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Hi I want to power this circuit from a vehicle battery.
Can anybody tell whether it is ok or not?
What about the zenner diode?Is it ok?
Thanks
Hi rezer thanks for your reply.
Ya there is a junction at the 1N4007 and the zener.
I applied the zenner because I'm scared if the battery gives more voltage than the regulator input (30V).
Also if the battery voltage varies the brightness of the LEDs vary.So if I add a zenner it will be stable.
Can I ignore the zenner? & I like to place only one IN4007 not two diodes.
That circles are LEDs.
So any suggessions?
A vehicel battery should not give you more than 14.4 Volt
what you might do is first use a 7810 for a stable 10Volt and much more power handeling than a zener, from there go further down to a 7805
Your 12V system in your car won't get up to 30V, 14.5 maybe. Put a 10uF cap on the output of your regulator and mount your .1uf cap as close to the µC power pin as possible. The 12V system should not vary that much that it would be noticable with your LEDs. But if it is, maybe you can power the transistor circuit from your 7805. The output will be stable regardless of what the battery is doing. You might want to consider using another 1N4007 in series. You could even use a 9V regulator to step the voltage down to the 5V reg. Your regulator will get a little warm with 8V dropped across it.
extualy if you feed it from a car battery you don't need a 1N4007
it works only as a polarity protection but it will stabilize nothing as that yo have already DC voltages also the capacitor is not needed this big in my opinion
use a smaller one if you want to build it compact
Robert-Jan
Instead the OP might use overvoltage protection diodes which are available for many different voltages. Every voltage beyond their rated input voltage will be shorted to ground respectively to +V. (Although they are pretty small from the package they can "digest" spikes with a total peak power of 600W.
Hans
Connecting any CMOS-circuit to the regulator output they will fry within no time. Spikes on the alternator DC have to be filtered thoroughly. So using some extra diodes in series with the regulator input pin might not be the worst idea. Instead the OP might use overvoltage protection diodes which are available for many different voltages. Every voltage beyond their rated input voltage will be shorted to ground respectively to +V. (Although they are pretty small from the package they can "digest" spikes with a total peak power of 600W.
Hans
When the regulator fails, the alt. puts 17v across the batt. and boils off the battery electrolyte rather vigorously.14.5 maybe.