12 volts dc reduced to 9 volts dc

[Ken Pachkowsky]

What would be the easiest way to do the above. I want to take 12v dc off a pin and reduce it to 9 volts. Would a zener diode do the job or is there a better way?

Thanks Guys.

Ken

[Harvey Gerst]

What would be the easiest way to do the above. I want to take 12v dc off a pin and reduce it to 9 volts. Would a zener diode do the job or is there a better way?

Thanks Guys.

Ken

A 3 pin LM7809 Voltage Regulator will do exactly what you want.

[Zilch]

I assume the 12V is regulated.

3.0V Zener in series will work, yes.

Four regular diodes in series will get you close.

9V Zener shunt regulator requires sizing the series resistor according to the load current.

Three-terminal regulator's also an option. Pay attention to providing the requisite bypass caps, tho.

How much current are you wanting to borrow?

[Ken Pachkowsky]

I assume the 12V is regulated.

Four regular diodes in series will get you close.

Zener shunt regulator requires sizing the series resistor according to the load current.

Three-terminal regulator's also an option, but it'd have to be low dropout (LDO) type. Three volts isn't much to work with....

Yes, I am taking the 12v dc off a regulated supply and reducing it to 9v dc.

Ken

[moldyoldy]

For a fixed-load, low-current app, the proper resistor would be an old-timer's way of doing it....all these new-fangled dingdy-dang gadgets anyway....let's see.... the negative sum of the applied voltages in a closed circuit shall equal zero.....or something like that.

[Hofmannhp]

.... the negative sum of the applied voltages in a closed circuit shall equal zero.....or something like that.

we call this "Kirchhoff's law"
HP

[moldyoldy]

we call this "Kirchhoff's law"
HP

Yeah, that's the ticket! Good ol' Kirchoff, gotta love him....

Then there's Fisherman's Law;

The first liar never stands a chance!

Oh well, I'd rather go swimmin' with bowlegged women.