Powering CMOS from 9 V powersupply

[squarewhite]

Hi

so far I've been using a 9V battery to power up my 4093 and 4060 chips. But I would like to use it with a 9v power supply, those which i can switch the voltages and plug it into a wall plug. Would this work or blow my chips?

[Cynosure]

Most CMOS chips can handle up to 15V, but check the datasheet for the chips you use just in case.

Most people start off with battery powered devices because it is safer.

If you want to use a power adapter, then there are a few things to keep in mind.

1. Make sure it is DC. You can use AC adapters too, but you need to do some extra work to make them compatible with CMOS chips.

2. Check the amperage. You generally want to use as low as you can get away with. I have used 100mA all the way up to 1A. But again, check the datasheet for this.

3. Check the polarity. Sending the power the wrong way through a cmos chip and destroy the IC. Sometimes the polarity is shown on the adapter, but sometimes it isn't. Either way, check it with a meter just to be sure.

4. Most DC adapters aren't very accurate. You should use a regulator to keep the voltage at a constant level. You usually want the supply voltage to be 3V higher than the regulator. Keeping that in mind, use a 12V DC adapter to power a 9V regulator (7809). Here is a good tutorial on using power regulators:

http://www.youtube.com/watch?v=GSzVs7_aW-Y

[squarewhite]

Thanks man!

That confirm my susupsion that i need to use a voltage regulator.

ok, back to the soldering table.

best

squarewhite

[Mikmo]

Most wall warts put out a higher voltage than printed on them. Probably because they are ment to be used with a device that has a voltage regulater in it.

I had one that was marked as 12V but actually put out 17V.

So always check with a meter!

[JingleJoe]

It's almost allways the case that a power supply outputs a higher voltage than rated, unless it's a proper engineering power supply or a computer PSU or something.
Voltage regulators are a must, the LM317 is a variable voltage regulator so if you can't find the regulator you are looking for you can set one of them to output whatever voltage you want

[-minus-]

I've hooked up multiple 'Lunetta' boards to both a cheap 9V dc supply and a Boss stomp box supply and have never had a need for regulators of any sort. For crappy 'blip bleep' circuits I don't think you should worry. Unless of course it makes you feel like a real Electrical Engineer... in which case may I suggest a lab coat. Doctors seem to do the same thing... walking around with a stethoscope around their necks all day.

[Draal]

[Uncle Krunkus]

Even if you use a transformer which can suppy 60 Amps a CMOS chip will only draw the current it needs. This is due to the internal resistance of the chip and Ohm's Law. I=V/R
The only issue is if you draw more current than the transformer can deliver. Then you'll blow the transformer, not the chip.
CMOS are rated up to 15V, that means if you give it 15V it's resistance will allow a certain current to flow through it. If you go above 15V, then you've got problems. Notice I'm talking Volts, not amps. The current is a function of the resistance, which is fixed.
Unregulated supplies are fairly accurate (volts wise) only when they are delivering close to their maximum current.
So if an unregulated DC supply can deliver 1 Amp, but you only draw 100mA from it, the voltage will be way higher than spec'd. Sometimes up to twice the voltage expected. This is because of a number of complicated formulas to do impedance and flux densisty, etc. which I read once but haven't remembered.

[squarewhite]

hi

thanks for all the infos.

of course, if it's a gig that i'm doing, battery powered works just fine, but i'm using it for an art installation. so hence the power supply. batteries would be too expensive over time.

best

[Psyingo]

fyi boss psu's are regulated.

[-minus-]

Don't forget, if it malfunctions or catches on fire, it's called a 'feature'!

[squarewhite]

yeah! its one off! it would be a show stealer.