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.

[pentictonklaus]

Hi Ken !

I used 7809 and 7812 ( 9 volt, 12 volt ) for many applications. Few things to watch:
need to be mounted like a transistor, that means that proper heat dissipation must be insured by using the paste on the back and of course the little insulators. Also try to get the little insulators for the mounting screw.
Usually they need + 3 Volt to trigger ( no problem in your case ) but buy more then you need since mass production makes them all different.
Current is usually up to 1 amp.

I used them as voltage regulator for ccp cameras in remote robots and often
had to put a small capacitor on to get rid of some distortion in the picture. I do not know how clean they work for audio applications.

Have a good day. I hope it's raining on the Island because it's raining in Penticton where it's not supposed to.
Good to see you back
Klaus

[Ken Pachkowsky]

Hi Ken !

I used 7809 and 7812 ( 9 volt, 12 volt ) for many applications. Few things to watch:
Good to see you back
Klaus

Thanks bud. Yes I used them on the project for my brothers sat receiver system.

Ken

[morbo!]

a long length of thin high resistance cable
should do the trick and no exrta components at all

[Ian Mackenzie]

Ken,

As you maybe aware more electronics store sell such convertors.

If you want to design it for the job you meed to establish the current drawn, is it constant current and the voltage tolerance of the sat rec.

Ideally it is better to adjust the prime regulator if that is possible.

National semiconductor may specialised voltage regulators with low dropout voltage for these sort of applications.

I would tend to buy an off the self convertor if locally available though.

Ian

[Ken Pachkowsky]

Ian

The 7809's worked great. I am enrolling in a electronics technician course at a local College. I want to get more into DIY projects and its your fault!

All kidding aside, it should be fun. I will be doing evening classes.

Ken

[Ian Mackenzie]

Okay,

So are you going into the electric blanket business...?

[Ken Pachkowsky]

Okay,

So are you going into the electric blanket business...?

always the comedian.