Reduction of DC Voltage

A fairly basic book about electricity should show you how to do this . Don't post your e-maill address on a public forum. Read up on some web security advice.

thank yo I will take your advise

This circuit is very small. All you need is a zener diode and a resistor. For the 1.5 volt version, just use a 1.5 volt zener.

Thank you very much for the info/help.

Sorry for the drifting topic below

I would also choose for the LM solution or the zener when it is only a small power you need (ref voltage)

indeed: don't put your e-mail on the forums. You have an integrated mail in your account and can send mails to specific people if you want.

Gwen

Or, use a small 3 pin linear regulator. How much current do you need?

i don't think using resistors to implement it is a good way, it is quite inefficient.

the dc/dc convertor or LDO will be more suitable.

It is no more inefficient, and probably less so, to use linear regulators (even LDO ones) than to use resistors. After all, a linear regulator is basically a glorified resistor! The bigger problem with using resistors is one of voltage regulation. Not a problem if your current demands never vary, but if they do, dc/dc converters may be a better solution, depending on current requirements.

-e

If the gods of electricity are with you, you can simply put a 12 volt lamp of appropriate wattage in each circuit -- then what would have been lost in heat in a resistor is now (possibly) welcome light. Of course, if the things you want to power are in a photo darkroom, then the light would not be so welcome, I suppose.

Use special dark room lamps, I once got a full box of them.

They also consume no electricity, very convenient design. (fit in traditional lamp sockets)

Gwen,

I couldn't tell if you were joking or not. Special dark room lamps that consume no electricity. They produce no light (i.e. remain dark) which is why they consume no electricity ?

Dark room lights produce red color light (at least that's what my father used back in the 60's) but they consume electricity.

OK I'm joking, my father once got a box of broken lamps, dark room lamps.

Red light is for black & white photo processing.

For colour you can have no light. (nice to work in, I once did this as a student)

Gwen

Electric lamps are actually "Dark Suckers", they suck in all the dark so you can see. This is why they go black when they stop working, because they are chock full of dark.

No, the light goes to the fridge.

Nearly 20 years ago there was an article in the famous "Journal Of Irreproduceable Results" about dark bulbs which when empowered make a room completely dark around. Unfortunately this valuable humorous paper vanished (as often to be watched with interesting things). I remember that the function was explained with a physical effect called the "collapsing Heufeld".
Regards Uwe

No, it is the fridge, go take a look.

Takes me back about two decades.

My sister asked me to accompany her when she bought her family's first fridge. She had a daughter, six years old, and a son, four years old who tagged along.

The kids were excited. At the appliance store, the girl opens the first fridge and quickly tells her mom, "Mom! Take this one! It's got space to put eggs in!" Her mom answers, "Er, Christine, all the fridges have egg trays." Christine opens another fridge and says, "Oh."

Finally, we make a decision and ask the salesman to test the fridge for us. He plugs it in and we wait for it to cool, keeping the door open. Kit notices the light. Soon, he's peeking around the door and slowly closes it, trying to see if the light will stay on when it's closed. The salesman says, "First fridge eh?"

Here we had a comical duo who had a little film on the fridge light: the discussion wheter it would switch out or not. It ended with the salesman entering the fridge to check himselve and the client to block the door and robbing the store.

By the way, is the problem with the DC voltege solved by now?

Wouldn't it be a good thing to find at a garage sale or something!

"No, the light goes to the fridge"

-----

That was cold.

If red light is for black and white photo processing, then would black light be best for red and white photo processing?

And if for colour I can have no light, then how can I have colour?

Ken writes: "And if for colour I can have no light, then how can I have colour?"

-----

If you took all the girls I knew
When I was single
And brought them all together for one night
I know they'd never match
My sweet imagination
And everything looks worse in black and white

How can we know all the girls you knew?

But it seams an interesting experiment.

Yea I like getting my feet wet. Real science.

I agree. This is the kind of scientific experimentation we should do as a CR4 project!

If I recall, there may be a few women in my past that actually would look better in black and white -- and soft focus would help too.

It is the light used for signalisation and appliances in the dark rooms.

a lot of the photographic processing happens in dark, only some fractions of the time it gets to see a very controlled amount and spectrum of it.

Never forget: even light that we don't see can have serious impact. And little accidents de travail, like Chernobyl were a big loss for photographic companies.

Actually, I was getting carried away with silliness. I've done some darkroom work in both color and monochrome. (And may do some again: the kids would get a kick out of it, I think -- and would especially appreciate seeing how things were done before the digital age.)

My remark was along the lines of "If a tree falls in the woods, and no one is there to hear it, does it make a sound?" If there is no light, is there color?

I don't know how we got on the subject of light bulbs but I am reminded of...

BACKGROUND: For those not in the US, we have a company here by the name of K-mart, which sells just about anything. They would have what they called "Blue light specials" where they would place a cart with a blue beacon on it at the merchandise they were discounting.

SO: Selling antennas at a ham radio show several years ago, I had a clear light bulb with a blown filament in it. I would set it (in a socket) out on the counter, and have my own "Blew Light Specials". It got lots of laughs, and also sold a heck of alot of antennas.

Bill

You may find Small Voltage converters-ICs for all purposes from Ref V to 10W in the market

What load are you powering? How much current is required. How much experience have you at electronics design? Is this DC source a battery or mains supply. If you had an AC supply it would be more economic. You could drop the voltage first to make the power loss as small as possible. DC DC converters can be very efficient if used with a constant load. Anything above 300mA would be best powered this way. As for the three terminal route the LM317 series is a good choice they come in 100ma to 3 amp rating then the 338k is a five amp type I have used all these and they are fairly robust so long as you obey the rules.